US 2016.0036042A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2016/0036042 A1 FORBERT et al. (43) Pub. Date: Feb. 4, 2016
(54) LITHIUM TRANSITION METAL PHOSPHATE Publication Classification SECONDARY AGGLOMERATES AND PROCESS FOR ITS MANUFACTURE (51) Int. Cl. HOLM 4/36 (2006.01) (71) Applicant: JOHNSON MATTHEY PUBLIC HOLM 4/58 (2006.01) LIMITED COMPANY, London (GB) HOLM 4/1397 (2006.01) COB 25/215 (2006.01) (72) Inventors: Rainald FORBERT, Moosburg (DE); (52) U.S. Cl. Gerhard NUSPL, Munchen (DE): CPC ...... H0IM 4/136 (2013.01); COIB 25/45 Nicolas TRAN, Nandlstadt (DE); (2013.01); H0IM 4/5825 (2013.01); H0IM Guoxian LIANG, Saint-Hyacinthe, 4/1397 (2013.01); COIP 2004/50 (2013.01); Quebec (CA) COIP 2006/12 (2013.01); COIP 2006/40 (21) Appl. No.: 14/777,120 (2013.01); HOIM 2004/028 (2013.01) (22) PCT Filed: Mar. 14, 2014 (57) ABSTRACT (86). PCT No.: PCT/EP2014/055.187 A Lithium-transition-metal-phosphate compound of formula S371 (c)(1), Lios, Fe,MPO) in the form of secondary particles made (2) Date: Sep.15, 2015 of agglomerates of spherical primary particles wherein the primary particles have a size in the range of 0.02-2pm and the (30) Foreign Application Priority Data secondary particles a mean size in the range of 10-40 pm and a BET surface of 16-40 m/g, a process for its manufacture Mar. 15, 2013 (EP) ...... 13159637.1 and the use thereof. Patent Application Publication Feb. 4, 2016 Sheet 1 of 9 US 2016/0036042 A1
8 Patent Application Publication Feb. 4, 2016 Sheet 2 of 9 US 2016/0036042 A1
Fig 388
Patent Application Publication Feb. 4, 2016 Sheet 3 of 9 US 2016/0036042 A1
Patent Application Publication Feb. 4, 2016 Sheet 4 of 9 US 2016/0036042 A1
& 4
Patent Application Publication Feb. 4, 2016 Sheet 5 of 9 US 2016/0036042 A1
Figire 5
& Patent Application Publication Feb. 4, 2016 Sheet 6 of 9 US 2016/0036042 A1
is: 86
Patent Application Publication Feb. 4, 2016 Sheet 7 of 9 US 2016/0036042 A1
8: 8. 88. 38 88: 88 capacity &isfg Patent Application Publication Feb. 4, 2016 Sheet 8 of 9 US 2016/0036042 A1
figre 8
a 20 to so ea too 20 as so taxity itik
US 2016/0036042 A1 Feb. 4, 2016
LITHIUM TRANSTION METAL PHOSPHATE 10007 Ravet et al. (Proceedings of 196' ECS meeting SECONDARY AGGLOMERATES AND 1999, 99-102) showed that carbon coated LiFePO with 1 PROCESS FOR ITS MANUFACTURE wt.-% carbon content can deliver a discharge capacity of 160 0001. The present invention relates to a lithium transition mAh/g at 80° C. at a discharge rate of C/10 using a polymer metal phosphate compound of formula Lios Fel-M, (PO4) electrolyte. in the form of secondary particles made of spherical primary 0008 Various approaches for preparing carbon compos particles, a process for its manufacture and its use as active ites and carbon coated LiMPO materials have been pub material in electrodes for secondary lithium-ion-batteries. lished so far. 0002 Rechargeable lithium ion batteries have been 0009. As discussed in the foregoing, the morphology of widely used in the past and in the presence as power sources the particles of LiMPO compounds is one of the essential key in a wide range of applications such as mobile phones, laptop factors for obtaining high charge and discharge capacities and computers, digital cameras, electrical vehicles and home the full theoretical capacity. However, synthesis of these com appliances. In rechargeable lithium ion batteries, cathode pounds especially via wet chemistry methods or hydrother materials are one of the key components and mainly devoted mal methods yields materials with large primary particles to the performance of the batteries. Since the pioneering work causing a negative impact such as a relatively low capacity of of Goodenough et al. (Padhi, Goodenough et al., J. Electro the related lithium cells. chem. Soc. 1997, 144, 1188) LiMPO compounds with 0010. The main disadvantages of powders comprising M=Fe, Mn, Ni and Co with an ordered olivine-type structure Smaller particles are a very small bulk and tap density and a have attracted an extensive attention due to their high theo different processing compared to compounds with larger par retical specific capacity of around 170 mAhg'. ticle sizes. 0003 LiMPO compounds adopt an olivine related struc 0011 EP 2 413 402 A1 discloses a process for the prepa ture which consists of hexagonal closed packing of oxygen ration of lithium iron phosphate wherein a mixture of hydro atoms with Li" and M" cations located in half of the octahe thermally prepared LiFePO and polyethylene glycol is wet dral sides and P' cations in /s of tetrahedral sides. This milled, the milled product dried and spray milled. structure may be described as chains along the c direction of (0012 US 2010/0233540A1 describes secondary agglom edge sharing MO octahedra that are cross-linked by the PO erates of primary particles of a lithium iron phosphate with an groups forming a three-dimensional network. Tunnels per olivine type structure with an average particle diameter of the pendicular to the 010 and 001 directions contain octahe secondary agglomerates of 5 to 100 um and with a porosity of drally coordinated Li' cations along the b-axis which are 50-40% consisting of primary particles of 50-550 nm repre mobile in these cavities. Among these phosphates, LiFePO is sented by the formula Li FeM(PO)X. The primary the most attractive, because of its high stability, low cost and particles are synthesized under Super critical hydrothermal high compatibility with environments. conditions. The secondary agglomerates according to US 0004. However, it is difficult to attain the full capacity 2010/0233540 A1 are obtained by a spray drying and have a because electronic conductivities are very low, which leads to spherical form and the BET-surface of these secondary initial capacity loss and poor rate capability and diffusion of agglomerates is 5-15 m/g. Li" ion across the LiFePO/FePO boundary is slow due its 0013 The disadvantages of the process as described in US intrinsic character. The pure electrical performance of 2010/0233540 A1 is the energy consumption during the dry LiFePO cathode material has also attracted interest among ing of the slurries which have a solid content of only 5-20%. many researches. The duration of the pyrolysis of the secondary agglomerates 0005. It was found that for LiFePO and related com pounds Small particle size and well shaped crystals are impor after spray drying is 10 hours and longer which also generates tant for enhancing the electrochemical properties. In particles increased energy costs. with a small diameter the Li-ions may diffuse over smaller 0014. It was therefore an object of the present invention to distances between the Surfaces and center during Li-interca provide lithium transition metal phosphates in particle form lation and de-intercalation and LiMPO on the particle sur comprising primary and secondary particles, whereas the sec face contributes mostly to the charge/discharge reaction. ondary particles are consisting of agglomerated primary par 0006) Substitution of Li" or Fe" with cations is a further ticles with or without carbon coating and which provide a way to attain full capacity as described for example by high bulk and tap density, therefore providing increased elec Yamada et al. J. Electrochem. Soc. 2001, 148, A960, A1153, trode density and hence the energy density of the battery A747 which reported the preparation of Mn-doped LiMn. when the lithium transition metal phosphate according to the 6 FeoPO. Further, doped Li Zno FeoPO was also pro present invention is used as the active electrode material. posed. Also doping with cobalt, titanium, Vanadium and 0015 This object is achieved by a lithium-transition molybdenum, chromium and magnesium is known. Herle et metal-phosphate of formula Lios, Fe, M.(PO) in the form al. in Nature Materials, Vol. 3, pp. 147-151 (2004) describe of secondary particles made of agglomerates of spherical lithium-iron and lithium-nickel phosphates doped with zirco primary particles wherein the primary particles have a size in nium. Morgan et al. describes in Electrochem. Solid State the range of 0.02-2 um, more preferably in the range of Lett. 7 (2), A30-A32 (2004) the intrinsic lithium-ion conduc 0.02-0.95 um or in other embodiments 0.7-0.95 um and the tivity in Li, MPO (M=Mn, Fe, Co, Ni) olivines. Yamada et al. secondary particles have a mean size (do) in the range of 5-40 in Chem. Mater. 18, pp. 804-813, 2004 deal with the electro um and a BET surface of 16-40 m/g. X is a number 0.3 and chemical, magnetic and structural features of Li,(MnFe) 0sy<1. PO, which are also disclosed e.g. in WO2009/009758. Struc 0016 Surprisingly it was found that the lithium-transition tural variations of Li,(MnFe)PO, i.e. of the lithiophilite metal-phosphates according to the invention when used as triphylite series, were described by Losey et al. The Canadian active material in electrodes for secondary lithium ion batter Mineralogist, Vol. 42, pp. 1105-1115 (2004). ies display a high electrical conductivity and an improved US 2016/0036042 A1 Feb. 4, 2016
electric capacity as well as improved rate characteristics com 0028. In one further embodiment, the lithium transition pared to batteries with electrodes having an active material of metal phosphates according to the invention have an excellent the prior art. tap porosity in the range of 55-65%. 0017. The lithium-transition-metal-phosphate according 0029. The lithium transition metal phosphate according to to the invention may be doped or non-doped. the invention display also excellent bulk, tap and press den 0.018. Therefore, the term “a or the lithium-transition sities (the latter especially when used as the single or one of metal-phosphate” means within the scope of this invention the active materials in a cathode) compared to prior art mate both a doped or non-doped lithium-transition-metal-phos rials. Their bulk density is in the range of 750-1250 g/l. Their phate as is also expressed by the Stoichiometric chemical tap density is in the range of 1250-1600 g/l. Further the formula Lios, Fe, M.(PO). Lithium may be present in lithium transition metal phosphate according to the invention slightly understoichiometric amounts (X-0.1), in exactly sto have an excellent press density in the range of 2000-2800 g/l. ichiometric (X-0.1) amounts or in excess Stoichiometry 0030. A higher bulk density allows for better and easier (overstoichiometric 0.1
are, in addition to the active material, also conductive carbon form of secondary agglomerates in the prior art. The milling blacks as well as a binder. According to the invention, how provides extremely fine primary particles, regardless how the ever, it is even possible to obtain a usable electrode with active initial particles have been synthesized which have a spherical material containing or consisting of the lithium-transition “ball-like” form in contrast to e.g. hydrothermally synthe metal-phosphate according to the invention without further sized primary particles which are in the form of needles or added conductive agent (i.e. e.g. conductive carbon black). platelets, as for example the primary particles of US 2010/ 0038 Any binder known perse to a person skilled in the art 0233540 A1 or U.S. Pat. No. 8,053,075 B2. The secondary can be used as binder, Such as for example polytetrafluoroet particles have a BET-surface of 16-40 m/g, in other embodi hylene (PTFE), polyvinylidene difluoride (PVDF), polyvi ments 16-30 m?g. After spray drying, the product according nylidene difluoride hexafluoropropylene copolymers to the invention, i.e. the Liolo, Fe,MPO, in the form of (PVDF-HFP), ethylene-propylene-diene terpolymers secondary agglomerates (with or without carbon) has a high (EPDM), tetrafluoroethylene hexafluoropropylene copoly packing density of the secondary agglomerates which in turns mers, polyethylene oxides (PEO), polyacrylonitriles (PAN), provides a high bulk and tap density. polyacryl methacrylates (PMMA), carboxymethylcelluloses 0.052 Without being bound by theory it appears that the (CMC), and derivatives and mixtures thereof. milling step yields a material with increased capacity and rate 0039 Typical proportions of the individual constituents of characteristics when used as electrode active material in sec the electrode material are preferably 90 parts by weight active ondary lithium ion batteries. material, e.g. of the lithium transition metal phosphate according to the invention, 5 parts by weight conductive I0053 Lios, Fe,MPO in particle form, i.e. the primary carbon and 5 parts by weight binder. A different formulation particles, can be synthesized by a variety of synthetic path likewise advantageous within the scope of the present inven ways, like for example via Solid-state reactions, co-precipi tion consists of 90-96 parts by weight active material and 4-10 tation, a hydrothermal method or by a so-called Supercritical parts by weight conductive carbon and binder. hydrothermal method and is for the purpose of the present 0040. The object is further achieved by a secondary invention not limited to a specific synthetic pathway. lithium secondary battery comprising a cathode according to 0054. In this specific embodiment of the process accord the present invention. ing to the invention, a carbon precursor compound, in other 0041. In further embodiments of the present invention, the words a carbon-containing material is added during step b. secondary lithium-ion battery according to the invention has This can be either pure carbon, such as e.g. graphite, acety a exemplary (but not limiting) cathode/anode pairs LiFePO// lene black or Ketjen black, or a carbon-containing precursor Li TiO2 with a single cell Voltage of approx. 2.0V, which is compound which then decomposes when exposed to the heat well suited as substitute for lead-acid cells or LiCo. Mn treatment in step e) to a carbonaceous residue. Representative FePO//Li TisC) with increased cell Voltage and improved nonlimiting examples of Sucha carbon containing compound energy density. are e.g. starch, maltodextrin, gelatine, a polyol, a Sugar Such 0042. A still further object of the invention was to provide as mannose, fructose, Sucrose, lactose, glucose, galactose, a a process for the synthesis of lithium transition metal phos partially water-soluble polymer Such as e.g. a polyacrylate, phates according to the invention. etc. and mixtures thereof. 0043. Accordingly the process for the synthesis of a 0055. In a further embodiment of the process according to lithium transition metal phosphate according to the invention the invention, an additional water soluble binder is added in comprises the following steps of stepb). In still a further embodiment of the process according 0044) a) providing Lios, Fe,MPO, in particle form, to the invention an additional dispersion agent is also added in 0.045 b) preparing an aqueous Suspension and—option step b). ally—adding a carbon precursor compound 0056. As a binder, a carbon containing compound which 0046 c) subjecting the aqueous Suspension to a milling additionally contains only hydrogen and oxygen and pyro treatment, wherein the milling energy introduced into the lyzes by applying a heat treatment to elemental carbon is suspension is set to a value between 800-2500 kWh/t, preferred. Especially preferred is lactose since the use of 0047 d) spray-drying of the milled suspension to obtain lactose increases the fluidity (and thus the handling) of the secondary agglomerates of Liolo, Fei-MPO4. Suspension in the further process steps, especially during 0048 e) heat treatment of the secondary agglomerates. spray-drying. Further binders useful for the purpose of the 0049 Optionally one or two particle classifying process invention are for example hydroxypropylcellulose, polyviny steps can be added after spray drying, e.g. Screening, sifting or lacohol, polyethyleneglycol, polyethylenoxide, polyacry sieving. In particular a sieving and/or sifting step may be lates etc. It is also part of the invention to use more than one carried out with a nominal mesh size of 33 um to 40 um. binder. 0050. The process according to the invention provides in 0057 The dispersion agent is water soluble and should one embodiment therefore Lios Fell-MPO in the form of also contain only carbon, hydrogen and oxygen, i.e. should secondary agglomerates with the properties as described also carbonize under a heat treatment regime. As an espe above and in another specific embodiment also Lico Fe. cially preferred dispergation agent, Solid organic acids can be MPO, comprising carbon in the sense as discussed before used in the process according to the invention. These acids hand. The particle size distribution of the so obtained product comprise but are not limited to citric acid, tartric acid etc. has a value for ds of 5-25um, in other embodiments 10-20 Further dispersion agents useful for the purpose of the inven um, preferably 15-20 Lum. tion are for example maleic acid, ascorbic acid, oxalic acid, 0051. The milling treatment in step c) before subjecting glycolic acid, 1,2,3,4 butanetetracarboxylic acid etc. and mix the Suspension to spray drying yields Surprisingly LioFe. tures thereof. Part of the invention is the use of a combination MPO, in the form of secondary agglomerates which does of different dispersion agents, e.g. citric acid and glycolic not have the disadvantages of the Lios Fei-MPO in the acid. US 2016/0036042 A1 Feb. 4, 2016
0058. It has been found that even tiny amounts of disper TABLE 1 sion agent (or a mixture of dispersion agents) of 0.05 mass-% (based on the mass of the lithium transition metal phosphate) Bulk and Tap Porosity vs. Milling Energy for C-LiFePO: are sufficient to obtain the desired product of the invention. Milling Energy Bulk Porosity Tap Porosity The amount of dispersion agent is usually in the range of Unmilled 85% 75% 0.05-2 mass-% (based on the mass of the lithium transition (prior art) metal phosphate). 1200 kWhit 729% S8% 0059. The suspension in step b) is preferably set to a pH 1600 kWhit 70% S6% value of between 6 and 8, preferably 7 by adding the acid 2000 kWhit 68% 55% dispersion agent. 0067 Low porosities, i.e. higher bulk and tap densities 0060. The process according to the invention includes an hence increased electrode densities and capacities can be optional pre-milling or dispergation treatment before step c). obtained by the material obtained by the process according to the invention compared to prior art materials and processes. 0061 The milling in step c) is carried out stepwise or 0068. This can be clearly seen by comparing the figures, continuously. Preferably the milling is carried out in a ball especially FIGS. 2 and 4, where the unmilled C LiFePO mill. The grinding beads have a diameter in the range of secondary agglomerates show clearly a higher porosity than 50-200 um, preferably in the range of 90-110 um. The grind the C LiFePO secondary agglomerates which have been ing beads consist of a material which does not contaminate Subject to a milling step prior to spray drying, in the present the desired Lios, Fe,MPO, according to the invention, i.e. example with a milling energy of 1200 kWh/t. This is due to a material which does not show abrasion and/or chemical the Smaller primary particles. reactivity. Preferably a non-metallic material is used (albeit 0069. After the milling step c) a further dispergation treat ment can be carried out. This treatment may be performed by stainless steel may also be used) as for example stabilized or any commercially available dispersing equipment, e.g. a non-stabilized Zirconia or aluminum oxide. The milling com rotor/stator disperser or a colloid mill, can be useful for sus partment and the milling unit are also coated and/or protected pensions re-agglomerating before spray drying in order to by a protective layer to avoid contamination of the product by prevent the atomizer from clogging and to decrease the vis abrasion and/or a chemical reaction. Preferably, the coating/ cosity of the Suspension prior to atomization. protective layer is made of or comprises polyurethane or a 0070. In a further embodiment of the process according to ceramic material, like Zirconia, Silicon nitride, silicon car the invention, the spray-drying in the step d) is carried out at bide, the latter being especially preferred. a temperature between 120-500°C. The spray drying can be carried out by any commercially available device for spray 0062. In a further embodiment of the process according to drying, e.g. a conventional co-current spray dryer. The atomi the invention, a dispersion agent is added during the milling Zation of the slurry is carried out with a rotary atomizer, a step c). The milling energy introduced into the Suspension is hydraulic nozzle, a pneumatic nozzle, a combined hydraulic set between 800-2500 kWh/t, preferably 1200-2000 kWh/t, and pneumatic nozzle with pressure on the slurry/suspension in a specific embodiment 1200-1400 kWh/t while the refer and a gaseous spraying medium, or a ultrasonic atomizer. ence mass (t) refers to the mass of the Solids in the Suspension. Particularly preferred are a rotary atomizer or a pneumatic This energy generates heat so that the Suspension has to be nozzle. 0071 Another surprising feature of the process of the cooled by a Suitable cooling device. Also during the milling present invention is the high content of Solids in the Suspen step, further dispersion agent(s) can be added Stepwise or sion/slurry used for spray drying compared to prior art pro continuously. cesses like for example as described in US 2010/0233540A1. 0063 Surprisingly it was found that the BET surface of the In the present invention a very high solid content can be used, products according to the invention is dependent on the mill namely 20-70%, preferably 40-65% in other embodiments 45-55%. ing energy introduced in the Suspension in step c) of the 0072 The drying of the suspension/slurry is carried out at process according to the invention. gas entry temperatures in the spray-drying apparatus of 120 0064. In specific embodiments of the present invention, 500° C., usually between 200-370°C. The exit temperatures the BET surface is typically in the range of 16-30 m/g. With are in the range of 70-120° C. The separation of the solid a millingenergy of 1200 kWh/tand grinding beads of 100 um, product from the gas can be done with any commercially LiFePO, with a BET surface of 19 m/g was obtained after available gas-Solid separation system, e.g. a cyclone, an elec pyrolysis in a rotary kiln. In another example C LiFePO trostatic precipitator or a filter, preferably with a bag filter with a BET surface of 28 m/g was obtained after pyrolysis in with a pulsedjet dedusting system. a stationary kiln. 0073. The dried secondary agglomerates of LioFe MPO are then subjected to a heat treatment. 0065. A similar phenomenon can be observed for the bulk 0074 The heat treatment (step e) of the process according and tap porosity which also appear to be dependent upon the to the invention) is in one embodiment of the invention a milling energy introduced in the Suspension/slurry: pyrolysis which is carried out at a temperature of between 0066. In a specific non-limiting embodiment, for 500° C. and 850° C., preferably between 600-800° C., espe C—LiFePO, according to invention, the following values cially preferred between 700-750° C. in a continuously oper can be found as shown in table 1 compared to a prior art ated rotary kiln. It is understood that any other suitable device C LiFePO synthesized according to US 2010/0233540 can be used as well for the purpose of the present invention. At without a milling step before spray drying. this temperature the carbon precursor compound present in US 2016/0036042 A1 Feb. 4, 2016 one embodiment of the process according to the invention is according to the manufacturers instructions. An air disper pyrolyzed to carbon which then wholly or at least partly sion pressure of 0.2 bar was used. covers the Lios, Fe, M.(PO) primary particles as a layer I0088. The Do value gives the value at which 90% of the (coating). The pyrolysis is typically carried out over a period particles in the measured sample have a smaller or the same of ca. 1 h. particle diameter according to the method of measurement. 0075 Nitrogen is used as protective gas during the pyroly Analogously, the Dso value and the Do value give the value at sis for production engineering reasons, but all other known which 50% and 10% respectively of the particles in the mea protective gases such as for example argon etc., as well as Sured sample have a smaller or the same particle diameter mixtures thereof, can also be used. Technical-grade nitrogen according to the method of measurement. with low oxygen contents can equally also be used. I0089. According to a particularly preferred embodiment 0076 Optionally one or two particle classifying process of the invention, the values mentioned in the present descrip steps can be added to remove either a coarse or a fine fraction tion are valid for the Do values, Dso values, the Do values as of the secondary agglomerates or both. This can be done by well as the difference between the Doo and Do values relative any commercially available equipment for particle classify to the volume proportion of the respective particles in the total ing e.g. a cyclone, an air classifier, a screen, a sieve, a sifter or Volume. Accordingly, the Do, Dso and Doo values mentioned a combination thereof. In one embodiment of the invention herein give the values at which 10 volume-% and 50 vol the heat treated secondary agglomerates of Li Fei-MPO, ume-% and 90 volume-% respectively of the particles in the are sieved on a tumbler screening machine with combined measured sample have a smaller or the same particle diam ultrasonic and airbrush cleaning at a nominal mesh size of 33 eter. If these values are obtained, particularly advantageous um to 40 um, preferably 40 um. The fine fraction is taken as materials are provided according to the invention and nega the product the coarse fraction is then rejected. tive influences of relatively coarse particles (with relatively 0077. The invention is further explained by way of Figures larger Volume proportion) on the processability and the elec and exemplary embodiments which are by no means meant to trochemical product properties are avoided. Preferably, the be limiting the scope of the invention. values mentioned in the present description are valid for the 0078 FIG. 1 is a SEM image of primary particles of Do values, the Dso values, the Doo values as well as the unmilled C LiFePO obtained by a hydrothermal method, difference between the Do and the Do values relative to both 007.9 FIG. 2 is a SEM image of secondary agglomerates percentage and Volume percent of the particles. of unmilled C LiFePO obtained by spray drying without a 0090. For compositions (e.g. electrode materials) which, milling step, in addition to the lithium-transition-metal phosphates accord 0080 FIG.3 is a SEM image of the primary particles of the ing to the invention contain further components, in particular secondary agglomerates of C LiFePO of the invention for carbon-containing compositions and electrode formula milled with 1200 kWh/t, tions, the above light scattering method can lead to mislead 0081 FIG. 4 is a SEM image of the secondary agglomer ing interpretations as the lithium-transition-metal phosphates ates ofC LiFePO of the invention milled with 1200 kWh/t. secondary agglomerates can form further and larger agglom I0082 FIG. 5 shows unmilled carbon coated LiFePO in erates within the dispersion. However, the secondary particle powder form size distribution of the material according to the invention can 0083 FIG. 6 shows another SEM photograph of second be directly determined as follows for Such compositions using ary particles of C LiFePO according to the invention SEM photographs: 0084 FIG. 7 shows the capacity of an electrode with 0091. A small quantity of the powder sample is suspended C—LiFePO according to the invention as active material in 3 ml acetone and dispersed with ultrasound for 30 seconds. 0085 FIG. 8 shows the capacity upon cycling of prior art Immediately thereafter, a few drops of the suspension are C LiFePO agglomerates of three different sources as active dropped onto a sample plate of a scanning electron micro material scope (SEM). The solids concentration of the suspension and I0086 FIG. 9 shows the capacity upon cycling of (un the number of drops are measured so that a large single-ply milled) C LiFePO agglomerates of prior art layer of powder particles forms on the support in order to prevent the powderparticles from obscuring one another. The EXPERIMENTAL drops must be added rapidly before the particles can separate by size as a result of sedimentation. After drying in air, the 1. General sample is placed in the measuring chamber of the SEM. In the Determination of the Particle-Size Distribution: present example, this is a LEO 1530 apparatus which is oper ated with a field emission electrode at 1.5 kV excitation 0087. The particle-size distributions for the secondary Voltage, an aperture of 30 Jum, an SE2 detector, and 3-4 mm agglomerates are determined using a light scattering method working distance. At least 20 random sectional magnifica using commercially available devices. This method is known tions of the sample with a magnification factor of 20,000 are perse to a person skilled in the art, wherein reference is also photographed. These are each printed on a DIN A4 sheet made in particular to the disclosure in JP 2002-151082 and together with the inserted magnification scale. On each of the WO 02/083555. In this case, the particle-size distributions at least 20 sheets, if possible at least 10 free visible particles were determined by a laser diffraction measurement appara of the material according to the invention, from which the tus (Mastersizer 2000 APA 5005, Malvern Instruments powder particles are formed together with the carbon-con GmbH, Herrenberg, Del.) and the manufacturer's software taining material, are randomly selected, wherein the bound (version 5.40) with a Malvern dry powder feeder Scirocco aries of the particles of the material according to the invention ADA 2000. The setting of the refractive index of the material are defined by the absence offixed, direct connecting bridges. was 0.00 because the Fraunhofer data analysis method was On the other hand, bridges formed by carbon material are used. The sample preparation and measurement took place included in the particle boundary. Of each of these selected US 2016/0036042 A1 Feb. 4, 2016 particles, those with the longest and shortest axis in the pro 768. The mean primary particle diameter was measured as jection are measured in each case with a ruler and converted described in EP 2 413 402 Al for FE-SEM images. to the actual particle dimensions using the scale ratio. For 0102 Spray drying was performed in a Nubilosa spray each measured Lios, Fe,MPO particle, the arithmetic dryer 1.25 m in diameter, 2.5 m in cylindrical height and 3.8 mean from the longest and the shortest axis is defined as m in total height. The spray dryer was equipped with pneu particle diameter. The measured Lios, Fe,MPO, particles matic nozzles type 970 form 0 S3 with an open diameter of 1.2 are then divided analogously to the light-scattering method mm and type 940-43 form 0 S2 with an open diameter of 1.8 into size classes. The differential particle-size distribution mm both of Disen-Schlick GmbH, Hutstrale 4, D-96253 relative to the volume of particles is obtained by plotting the Untersiemau, Germany. Drying gas was Supplied by a con Volume of the associated particles in each case against the size trolled suction fan and heated electrically before entering the class. The Volume of the associated particles V is approxi spray dryer. The dried particles were separated from the gas mated by the sum of the spherical volumes of each of these n stream by a bag filter and recovered by a pulsedjet dedusting particles V, calculated from their corresponding particle system. Amount of drying gas, gas inlet temperature and diameters d: outlet temperature were controlled by a process control sys tem. The outlet temperature control governed the speed of the slurry feed pump. Atomization gas was Supplied by the com pressed air distribution of the plant and its pressure was controlled by a local pressure controller. 0103 Pyrolysis was performed in a rotary kiln type LK 0092. The cumulative particle-size distribution from 900-200-1500-3 of HTM Reetz GmbH, Köpenicker Str. 325, which Do, Dso and Doo can be read directly on the size axis D-12555 Berlin, Germany. Its heated rotary tube was 150 mm is obtained by continually totaling the particle Volumes from in diameterand 2.5 m in length. It provided a preheating Zone, the Small to the large particle classes. three heated separately controlled temperature Zones, and a 0093. The described process was also applied to battery cooling Zone. The inclination of the tube could be adjusted electrodes containing the material according to the invention. and its rotational speed was variably controlled. Product was In this case, however, instead of a powder Sample a fresh cut supplied by a controlled screw feeder. Product supply, the kiln or fracture surface of the electrode is secured to the sample itself and product outlet could be blanketed by nitrogen. The holder and examined under a SEM. amount of pyrolyzed product could be continuously moni 0094 BET measurements were carried out according to tored by a balance. DIN-ISO 92.77. 0104 Milling was performed in an agitated ball mill 0095 Bulk density was determined according to ISO 697 MicroMediaTM P2 by Bihler AG, CH-9240 Uzwil, Switzer (formerly DIN 53912). land, with SSiC ceramic cladding. It was filled with yttrium 0096 Tap density was measured according to ISO 787 stabilized zirconium oxide beads of nominal 100 Lum (80-130 (formerly DIN 53194). um) diameter. Its peripheral speed was controlled between 0097. Press density and Powder Resistivity were mea 6.5 and 14.0 m/s. The milling compartment had a volume of sured at the same time with a combination of a Lorenta-CP 6.3 liter. The drive had a power rating of 30 kW. Heat was MCP-T610 and a Mitsubishi MCP-PD 51 device. The Pow removed through the walls of its milling compartment by der Resistivity is calculated according to formula: cooling water. The slurry to be milled was passed from an agitated vessel via a controlled peristaltic pump through the Powder resistivity S2cm)=resistance S2xthickness mill back to the vessel. This closed loop was operated until the cm xRCF desired specific milling energy had been reached. (0098 (RCF=device dependent Resistivity Correction Factor) 0099 Pressure density was calculated according to the 2. Synthesis of the Primary Particles of Lithium formula Transition Metal Phosphates 0105. The lithium transition metal phosphates, for example LiFePO LiCoPO, LiMnPO, were obtained via Pressure density g/cm = hydrothermal synthesis according to WO2005/051840. The mass of sample g synthesis method can be applied to all lithium transition metal X r2 cm2xthickness of the sample cm) phosphates like Liolo, Fe,Mg,(PO4) Liolo, Fe,Nb,(PO4), Lio9 Fe-Co.(PO4) Liolo Fel-Zn(PO4) Lio9 Fei-All, C) Liolo Fe(Zn, Mg),(PO4), Liolo, Fe,Mn,(PO4) as 0100. The porosities were obtained from the correspond W. ing measured densities according to the following formula: 0106 The term “hydrothermal synthesis or conditions' means for the purpose of the present invention temperatures 1 - density of 100° C. to 200° C., preferably 100° C. to 170° C. and quite Porosity = true material density particularly preferably 120° C. to 170° C. as well as a pressure of 1 bar to 40 bar vapour pressure. In particular, it has sur prisingly been shown that the synthesis at the quite particu (the true material density was determined according to ISO larly preferred temperature of 120-170° C., in particular at 1183-1). For pure LiFePO, the value is 3.56 kg/1. 160+5°C., leads to an increase in the specific capacity of the 0101. The SEM images taken with the LEO 1530 appara thus-obtained Lios, Fe, M.(PO) according to the inven tus were recorded in tif file format at a resolution of 1024x tion compared with reaction at more than 160° C.-5°C. US 2016/0036042 A1 Feb. 4, 2016
0107 The intermediate product is typically obtained in the Example 2 form of a wet filter cake before preparing an aqueous Suspen sion according to process step b). Preparation ofC LiMnPO Secondary 3. Synthesis of the Lithium Transition Metal Agglomerates Phosphates in the Form of Secondary Agglomerates 0118. The synthesis was carried out as in example 1. Example 1 Instead of LiFePO, LiMnPO was used. 0119 The product obtained had a bulk density of 1030 g/l. Preparation of Carbon Coated LiFePO Secondary the tap density was 1400 g/l and the press density 2190 g/l. Agglomerates The BET-surface was 24 m/g. The characteristics of this 0108. The wet filter cake consisting essentially of carbon product were: coated LiFePO primary particles (C-LFP) typically in form of needles and platelets is mixed with 10 mass-% of lactose (based on the solid lithium iron phosphate). A suspension Term Measured Unit Method with 52.5% solid content is prepared with distilled water to Carbon-content 2.2 wt % CS-Analyzer maximize the efficiency of the following milling step. Mean particle size 85 ill SEM 0109 The suspension is then continuously milled with a Primary particles ball mill with grinding beads having a diameter of 90-110 um. PSD (do) 3.6 m Laser Diffraction (Malvern) The grinding beads consist of a stabilized Zirconium oxide PSD (do) 14.9 m Laser Diffraction (Malvern) PSD (doo) 30.5 m Laser Diffraction (Malvern) ceramic. The milling reactor was cladded with silicon carbide Specific surface 24 m/g Nitrogen adsorption (BET) to avoid a contamination of the product and to allow an 808 effective cooling. Bulk Density 1030 gll 0110. The energy introduced into the suspension is Tap Density 14OO gll Automatic tap density analyzer removed by cooling the Suspension, wherein the main amount Volume 25 2cm Powder Resistivity Analyzer of the heat is directly removed by the mill. Resistivity 0111. The mechanical energy applied to the Suspension Press Density 2.19 g/cm Powder Resistivity Analyzer was 1200 kWh/t. During milling a total of 1.5 mass-% of pH value 8.8 pH electrode Spec. Capacity 150 mAh/g C-LiMnPO/LiPF citric acid (based on the solid lithium iron phosphate) were EC-DMC/Li added. Charge Discharge at C/10, 0112. After milling the suspension was spray-dried via a 25o C. pneumatic nozzle. The solid content of the Suspension was Range: 4.3 V-2.0 V 52.5%. 0113. During spray-drying the gas inlet temperature was 300° C., the outlet temperature was 105° C. 0114. The separation of the solid product from the gas was Example 3 carried out in a bag filter. The dried agglomerate was further pyrolized in inert gas atmosphere at 750° C. in a rotary kiln. 0115 The product obtained had a bulk density of 1030 g/l. Preparation of C-LiCoPO secondary agglomerates the tap density was 1480 g/l and the press density 2230 g/l. 0116 SEM images were recorded of the so obtained prod 0.120. The synthesis was carried out as in example 1. uct (see FIGS. 3 and 4). Instead of LiFePO, LiCoPO was used. 0117 The characteristics of this product were: I0121 The product obtained had a bulk density of 1050 g/l. the tap density was 1390 g/l and the press density 2180 g/l. The BET-surface was 25 m/g. The characteristics of this Term Measured Unit Method product were: Crystal >95% NAA XRD Structure Olivine LiFePO Term Measured Unit Method Carbon-content 1.9 wt % CS-Analyzer Mean particle size 71 ill SEM Carbon-content 2.0 wt % CS-Analyzer primary particles Mean particle size 81 ill SEM PSD (do) 4.7 m Laser Diffraction (Malvern) Primary particles PSD (d.so) 15.9 m Laser Diffraction (Malvern) PSD (do) 3.9 m Laser Diffraction (Malvern) PSD (doo) 36.4 m Laser Diffraction (Malvern) PSD (d.so) 15.1 Im Laser Diffraction (Malvern) Specific surface 19 m/g Nitrogen adsorption (BET) PSD (doo) 33.8 m Laser Diffraction (Malvern) 808 Specific surface 25 m/g Nitrogen adsorption (BET) Bulk Density 1030 gll 808 Tap density 1480 gll Automatic tap density Bulk Density 1 OSO gll analyzer Tap Density 1390 gll Automatic tap density analyzer Volume 13.9 cm Powder Resistivity Analyzer Volume 26 2cm Powder Resistivity Analyzer Resistivity Resistivity Press Density 2.23 g/cm Powder Resistivity Analyzer Press Density 2.18 g/cm Powder Resistivity Analyzer pH value 9.5 pH electrode pH value 9.1 pH electrode Spec. Capacity 158.4 mAh/g C-LiFePO/LiPF - Spec. Capacity 150 mAh/g C-LiCoPO/LiPF EC-DMC/Li EC-DMC/Li Charge Discharge at C/10, Charge Discharge at C/10, 25o C. 25o C. Range: 4.0 V-2.0 V Range: 5.2 V-3.0 V US 2016/0036042 A1 Feb. 4, 2016
Example 4 to be adjusted according to the Voltage profile of the system, e.g. for LiFeo. Mino,PO between 4.3 and 2.0 V. Preparation of C-LiMnFeoPO Secondary I0128 FIG. 1 is a SEM image of primary particles of Agglomerates unmilled C LiFePO of prior art obtained by a hydrother mal method (WO 2005/051840 A1. The platelet shape of the 0122) The synthesis was carried out as in example 1. fine crystals can be seen. Instead of LiFePO, LiMnozFeoPO was used. I0129 FIG. 2 is a SEM image of secondary agglomerates 0123. The product obtained had a bulk density of 1020 g/l. of unmilled C LiFePO obtained by spray drying without a the tap density was 1430 g/l and the press density 2210 g/l. milling step, i.e. secondary agglomerates obtained from the The BET-surface was 27 m/g. The characteristics of this primary particles as shown in FIG.1. The irregular shape is product were: clearly visible. I0130 FIG.3 is a SEM image of the primary particles of the secondary agglomerates of C-LiFePO of the invention Term Measured Unit Method milled with 1200 kWh/t and FIG. 4 is a SEM image of the Carbon-content 2.3 wt % CS-Analyzer secondary agglomerates of C-LiFePO of the invention Mean primary 70 ill SEM milled with 1200 kWh/t. The differences in particle size and particle size morphology are clearly visible. The properties with respect to PSD (do) 2.5 m Laser Diffraction (Malvern) PSD (do) 13.8 m Laser Diffraction (Malvern) density are described above. PSD (doo) 31.8 m Laser Diffraction (Malvern) I0131 FIG. 4 shows C LiFePO agglomerates according Specific surface 27 m/g Nitrogen adsorption (BET) to the invention (example 1) with mean particle sizes of 10-20 808 um (ds 15.9), having a higher density, better flowability and Bulk Density 102O gll Tap Density 1430 gll Automatic tap density analyzer less dusting than the powders of the prior art as can be seen Volume 18 2cm Powder Resistivity Analyzer from the figures and their homogeneous particle morphology. Resistivity (0132 FIG. 5 shows primary particles of C LiFePO Press Density 2.21 g/cm Powder Resistivity Analyzer according to the invention. In comparison to FIG. 1 it is pH value 8.7 pH electrode Spec. Capacity 151 mAh/g C-LiMno.67FeoPO/LiPF clearly visible that the primary particles of C LiFePO EC-DMC/Li agglomerates of the prior art are much coarser. Charge Discharge at C/10, 0.133 FIG. 6 shows another SEM photograph of second 25o C. ary particles of C-LiFePO according to the invention. The Range: 4.3 V-2.0 V secondary particle size of 15-20 um facilitates the electrode processability, namely enables that a homogeneous disper sion of the particles of the active material/conductive agent/ 4. Preparation Electrodes binder within the electrode can be obtained. With active mate rial of the prior art, either in agglomerate or powder form 0.124 Electrodes were prepared by mixing 90 parts per inhomogeneities are observed which deteriorate the cycling weight of lithium-transition-metal-phosphate of the inven characteristics and the capacity of the electrode. Further tion or carbon coated lithium-transition-metal-phosphate uncontrolled formation of locally "concentrated agglomer together with 5 parts of carbon. 5 parts of a binder were ates of active material is avoided. Thus an electrode according diluted in N-methyl-2-pyrrolidon solution and added to the to the invention shows a higher capacity and conductivity mixture. The mixture was kneaded to give a slurry. The slurry than electrodes with active material of the prior art. The was applied by a doctoralblade to an aluminium collector foil agglomerates according to the invention are more stable serving as a collector. The film was dried at 60° C. under towards external pressure than agglomerates of prior art. It reduced pressure of 500 mbar for 2 h. was observed that during processing of the electrode formu 0.125. A platen press was used for densification. But any lation (preparation of a dispersion and applying to an elec other press like for example a calander press is suitable as trode substrate) 95% of the agglomerates according to the well. The pressing force was in the range of from 500 to invention remained intact, whereas the more brittle agglom 10000 N/cm, preferably 5000 to 8000 N/cm. The target erates of the prior art remained only to 50% intact. value for the coating (active material) packing density was 0.134 FIG.7 above shows the capacity of an electrode with >1.5 g/cm or higher, more preferably >1.9 g/cm. carbon coated LiFePO (C-LFP) according to the invention 0126 The electrodes were dried for 2 more hours under made in accordance with example 1 as active material, indi vacuum, preferably at elevated temperatures of about 100° C. cating excellent cycling characteristics. The electrode formu Cells were assembled as "coffee bag” cells (batteries), which lation was 90/5/5 weight parts C LiFePO (carbon coated consist of an aluminium coated polyethylene bag. Lithium LiFePO)/Super P Licarbon/Binder PVDF 21216. The elec metal was used as the counter electrode. 1M LiPF was used trode density was 1.7 g/cm, the loading was 4.35 mg/cm. as electrolyte in a 1:1 mixture of ethlylenecarbonate (EC): 0.135 FIG. 8 shows the capacity upon cycling of prior art diethylenecarbonate (DEC). In each battery one layer of a carbon coated LiFePO agglomerates of three different microporous polypropylene-foil (Celgard 2500; Celgard sources. The electrode formulation was 90/5/5 weight parts 2500 is a trademark) having lithium ion permeability was C LiFePO/Super P Li carbon/Binder PVDF 21216. The used as the separator. The bags were sealed using a vacuum electrodes were prepared as described in the foregoing and sealing machine. FIG. 7. 0127. Measurements were performed in a temperature 0.136. As can be seen compared to FIG. 7 and table 1, all controlled cabinet at 20° C. using a Basytec cell test system prior art material showed inferior electrochemical properties. (CTS). Voltage range for cycling was between 2.0V and 4.0V 0.137 FIG. 9 shows the capacity upon cycling of carbon for pure LiFePO. For other cathode materials the voltage had coated LiFePO agglomerates of prior art (LFP-prior art) US 2016/0036042 A1 Feb. 4, 2016
obtained according to the combined teachings of WO 2005/ 35. Process for the manufacture of a Lithium-transition 051840 A1 and US 2010/0233540 (see below)(unmilled). metal-phosphate according to claim 28 comprising the fol Also here, the electrochemical properties of C LiFePO lowing steps: according to the invention proved to be superior (see in FIG. a) providing Lios Fel-M, (PO) in particle form, 7 and table 1). The material of sources A, B, C were obtained b) preparing an aqueous Suspension and optionally— from Hanwha Chemicals (C-LFP: grade LFP-1000) (source adding a carbon precursor compound, B), VSPC Co. Ltd. (C-LFP grade: generation3) (source C) or c) Subjecting the aqueous Suspension to a milling treat were made according to US 2010/0233540 (C-LFP source A). The Agglomerates C-LFP Prior Art were obtained by ment, wherein the milling energy introduced into the synthesizing LFP primary particles according to WO 2005/ suspension is set to a value between 800-2500 kWh/t, 051840A1 followed by spray drying according to the process d) spray-drying of the milled Suspension to obtainagglom described in US 2010/0233540. erates of Liolo, Fe, M.(PO4), 0.138. The following summarizes the electric properties of e) heat treatment of the agglomerates. the materials in FIGS. 7-9. It can be seen that C-LFP accord 36. Process according to claim 35, wherein the carbon ing to the invention is better than the prior art materials A, B precursor compound is selected from starch, maltodextrin, and C and C-LFP agglomerates prior art and has better pro gelatine, a polyol, a Sugar Such as mannose, fructose, Sucrose, cessability with a better flowability and less dusting and more lactose, glucose, galactose, a partially water-soluble polymer homogeneous distribution in the electrode formulation. or mixtures thereof. TABLE 1. Electric properties of material according to the invention and of prior art
C-LFP Discharge Agglomerates Agglomerates Agglomerates Agglomerates C-LFP Rate Unit of source A of source B of source C prior art invention Capacity C/10 mAh/g 1485 156.4 150.4 153.4 158.4 1 C mAh/g 141.2 1431 139.4 144.2 153.3 3 C mAh/g 1298 132.6 127.4 1340 145.5 5 C mAh/g 125.4 126.2 119.6 127.4 1401 10 C mAh/g 11S.O 116.1 105.7 114.O 1286 Volumetric C/10 mWh/cm 998 898 923 960 1048 Energy 1 C mWh/cm 926 804 836 875 1OOO Density 3 C mWh/cm 816 729 742 781 924 5 C mWh/cm 770 675 679 719 870 10 C mWh/cm 666 587 574 60S 760 Press kg/m 2O3O 1810 2OOO 1915 2060 Density PSD d10 m 7.8 O.92 5.8 4.5 4.7 d50 m 25.4 6.1 1S.O 14.8 15.9 d90 m 58.0 17.1 28.0 30.8 36.4
1-27. (canceled) 37. Process according to claim 36, wherein in step b) an 28. Lithium-transition-metal-phosphate compound of for additional water soluble binder and/or an additional disper mula Liolo, Fe, M.(PO) with x<0.3 and 0sys1 and M is a sion agent is added. metal or semimetal or mixtures thereof in the form of second 38. Process according to claim 35, wherein the suspension ary particles made of agglomerates of spherical primary par in step b) is set to a pH value of between 6 and 8. ticles, wherein the primary particles have a size in the range of 39. Process according to claim 35 including an optional 0.02-2 Lum and the secondary particles have a mean size (ds) pre-milling or dispergation treatment before step c). of 5-40 um and a BET surface of 16-40 m/g and wherein the 40. Process according to claim 35, wherein the milling in lithium-transition-metal-phosphate has a tap density of 1250 step c) is carried out stepwise or continuously. 1600 g/l. 41. Process according to claim 40, wherein the milling is 29. Lithium-transition-metal-phosphate according to carried out by a ball mill having grinding beads wherein the claim 28 with a bulk porosity of 65-80%. diameter of the grinding beads is in the range 50-200 um, 30. Lithium-transition-metal-phosphate according to preferably 90 to 110 um. claim 28 with a tap porosity of 55-65%. 42. Process according to claim 35, wherein during the 31. Lithium-transition-metal-phosphate according to milling step c), a dispersion agent is added. claim 28 with a bulk density of 750-1250 g/l. 43. Process according to claim 35, wherein after the mill 32. Lithium-transition-metal-phosphate according to ing step c) a further dispergation treatment is carried out. claim 28 with a press density of 2000-2800 g/l. 44. Process according to claim35 wherein the spray-drying 33. Lithium-transition-metal-phosphate according to in the step d) is carried out at a inlet drying gas temperature claim 28 which is LiFePO, LiMnPO, or Lios. Fe,M- between 120-500° C., preferably 200-370° C. nPO. 45. Process according to claim 35, wherein the heat treat 34. Lithium-transition-metal-phosphate according to ment in step e) is a pyrolysis carried out at a temperature claim 28 wherein the primary particles have a conductive between 500-850° C. carbon deposit on at least a part of the Surface of the primary 46. Lithium-transition-metal-phosphate according to particles. claim 29 with a tap porosity of 55-65%. US 2016/0036042 A1 Feb. 4, 2016 10
47. Lithium-transition-metal-phosphate according to claim 29 which is LiFePO, LiMnPO, or Lios. Fe,M- nPO4. 48. Lithium-transition-metal-phosphate according to claim 29 wherein the primary particles have a conductive carbon deposit on at least a part of the Surface of the primary particles. 49. Process for the manufacture of a Lithium-transition metal-phosphate according to claim 29 comprising the fol lowing steps: a) providing Lios, Fe, M.(PO) in particle form, b) pre paring an aqueous Suspension and—optionally—adding a carbon precursor compound, c) Subjecting the aqueous Suspension to a milling treat ment, wherein the milling energy introduced into the suspension is set to a value between 800-2500 kWh/t, d) spray-drying of the milled Suspension to obtain agglom erates of Liolo, Fe, M.(PO4), e) heat treatment of the agglomerates. k k k k k