USOO5955219A United States Patent (19) 11 Patent Number: 5,955,219 Nishijima et al. (45) Date of Patent: Sep. 21, 1999

54) LITHIUM NICKEL COPPER COMPOSITE WO 90/10735 9/1990 WIPO. OXDE AND ITS PRODUCTION PROCESS OTHER PUBLICATIONS AND USE Arai et al. Electrochemical and Structural Study. ...) Solid 75 Inventors: Motoaki Nishijima, Gose; Takehito State Ionics, vol. 106, pp. 45-53, Feb. 1998. Mitate, Yamatotakada, both of Japan Solid State Ionics. 44(1990)-87–97 This is referred to P5 L.16-24 of the specification. 73 Assignee: Sharp Kabushiki Kaisha, Osaka, Japan Solid State Ionics. 46 (1991) 243-247. Journal of Solid State Chemistry 105(1993)410–416. 21 Appl. No.: 08/980,227 Patent Abstracts of Japan, bol. 095, No. 010, Nov.30, 1995 & JP 07 192721 A (Sanyo Electric Co Ltd), Jul. 28, 1995. 22 Filed: Nov. 28, 1997 Patent Abstracts of Japan, vol. 017, No. 608 (E-1457), Nov. 30 Foreign Application Priority Data 9, 1993 & JP 04190177A (Matsushita Electric Ind Co Ltd), Jul. 30, 1993. Nov. 29, 1996 JP Japan ...... 8-319400 Patent Abstracts of Japan, vol. 018, No. 414 (E-1587), Aug. (51) Int. Cl...... HO1 M 4/48 3, 1994& JP06 124707 A (Matsushita Electric Ind Co Ltd), 52 U.S. Cl...... 429/220; 429/223; 429/231.1; May 6, 1994. 423/641 Primary Examiner Maria Nuzzolillo 58 Field of Search ...... 429/220, 223, Assistant Examiner-Carol Chaney 429/231.1; 423/593, 604, 641, 594 Attorney, Agent, or Firm Nixon & Vanderhye, P.C. 56) References Cited 57 ABSTRACT U.S. PATENT DOCUMENTS A lithium nickel copper composite oxide having the com 5,378,560 1/1995 Tomiyama ...... 429/217 positional formula LiNiCuO (0.0carbon material or the like. FOREIGN PATENT DOCUMENTS 6-111821 4/1994 Japan. 11 Claims, 7 Drawing Sheets

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SunOO / AOuelu U.S. Patent Sep. 21, 1999 Sheet 7 of 7 5,955,219

5,955,219 1 2 LITHIUM NICKEL COPPER COMPOSITE trochemically deserted from Lilayers, the repulsion between OXDE AND ITS PRODUCTION PROCESS Ni-O layers grows larger and destroys the crystallographic AND USE structure of LiNiO itself. This is the reason for the above deterioration. In the case where lithium atoms are electro CROSS-REFERENCE TO RELATED chemically deserted from the Li layers, nickel atoms from APPLICATIONS the Ni-O layers also fall into lithium sites and this causes This application is related to Japanese application No. the deterioration of the battery capacity. HEI 8(1996)-319400, filed on Nov. 29, 1996 whose priority There are many kinds of ways to overcome these disad is claimed under 35 USC S 119, the disclosure of which is Vantages. However, the above phenomena come from the incorporated by reference in its entirety. basic structure of LiNiO, so that it is impossible to find the fundamental way for overcoming these disadvantages. For BACKGROUND OF THE INVENTION the above-mentioned reasons, there are fundamental prob lems if the known lithium nickel composite oxide Such as 1. Field of the Invention LiNiO is used as the positive electrode active material of The present invention relates to a lithium nickel copper 15 the Secondary battery. Therefore, there has been a longing composite oxide and its production process and use. for a new positive electrode active material in order to Especially, Said composite oxide has the use as a positive provide the lithium Secondary battery having excellent electrode active material of a nonaqueous Secondary battery properties, especially large charge/discharge capacity. which can be charged and discharged with a great capacity AS a negative electrode active material, on the other hand, and has an excellent cycle characteristic. usable are metallic lithium, lithium alloys (e.g., lithium 2. Related Art aluminum or the like), carbon materials, Substances which Recently, a Secondary battery is often used as an electric can be intercalated and deintercalated with lithium ions power Source of a portable electronic device in terms of (e.g., conductive polymers such as polyacetylene, economy. There are many kinds of Secondary batteries. polythiophene, poly-p-phenylene or the like), transition Among them, a nickel-cadmium battery is most popular now 25 metal oxides, transition metal Sulfide, transition metal and recently a nickel-hydrogen battery is becoming popular. nitride, lithium transition metal oxide, lithium transition Meanwhile, a lithium Secondary battery using lithium for an metal Sulfide or lithium transition metal nitride. These electrode produces high output Voltage and has high-energy materials may be used alone or as a composite thereof. density. Therefore, the lithium Secondary battery is practi Among them, when metallic lithium or lithium alloy Such cally utilized in Some extent, and is now eagerly Studied to as lithium aluminum is used as the negative electrode active improve its performance. material, the battery thereof has the great capacity per unit One of the materials for a positive electrode of the lithium weight and high energy density. However, in this case, Secondary battery, which is commercially available now, is dendritical crystal, i.e., So-called dendrite appears and grows LiCoO. However, cobalt as the raw material of LiCoO is on the Surface of the metallic lithium during the repeated expensive. Therefore, it is recognized that LiNiO will be a 35 charging and discharging processes. In a short time, the good material for the positive electrode of the lithium grown dendrite may contact the positive electrode to cause Secondary battery for next generation, because LiNiO has a short circuit within the battery or, in the worst case, a the Same crystallographic Structure and shows almost the danger of firing. same electrochemical behaviors as LiCoO, and nickel as 40 Therefore, it is preferred that as the negative electrode the raw material of LiNiO is less expensive than cobalt. active material for Secondary battery used is the material It is known that LiNiO is more stable than any other which is not metallic lithium or lithium aluminum alloy and lithium nickel composite oxide and can be prepared rela can be intercalated and deintercalated with lithium ions into tively with ease. In the case where LiNiO is used for the the inside. Among them, it is thought that the carbon positive electrode active material of the nonaqueous Sec 45 material is the most promising material in terms of energy ondary battery, lithium atoms are electrochemically deserted density and price. from the crystallographic structure as a result of charging. Nickel exists in the state of Ni" in the crystal of LiNiO. SUMMARY OF THE INVENTION When lithium atoms are deserted from crystal of LiNiO, The present invention aims to provide a lithium nickel nickel is oxidized from 3+ into 4+. Maximum oxidation 50 copper composite oxide which has a novel Structure and number of nickel is 4+ and Ni" cannot be oxidized any enables to form a novel positive electrode active material more. Even if all lithium atoms are electrochemically drawn having larger capacity than conventional ones, and further to out from the crystal of LiNiO, the electrical capacity of the provide a Secondary battery having large capacity by com positive electrode never becomes more than one electron bination of this novel positive electrode active material and equivalent. Namely, the electrical capacity of the positive 55 electrode is theoretically no more than 274.6 mAh/g. a negative electrode active material made from a carbon However, when the lithium Secondary battery using material or the like. LiNiO as the positive electrode active material is actually Thus, the present invention provides the lithium nickel charged and discharged, the capacity of the positive elec copper composite oxide having the compositional formula trode is around half of the above-mentioned theoretical 60 LiNiCuO (0.0oxygen occupies the 4i Site. FIG. 2 place of conventional LiNiO in order to achieve the above shows the basic structure of LiNiCuO (0.0crystal Structure is deserted, the crystal Structure becomes to shares their opposite Sides to form a linear chain; and the collapse, thereby, causing the decrease of the capacity. To chains located parallel to another linear chain of (Ni-Cu) prevent this, at first the crystal containing a lot of lithium or O. Square planer coordination units with their planes facing alkaline metal atoms should be prepared. Then, when Some opposite to each other to form a kind of layers ((Ni-Cu)O of lithium or alkaline metal atoms are deserted from that layers). FIG. 3 shows the configuration in this structure. crystal, the collapse of the crystal does not occur and the Lithium atoms exist between one (Ni-Cu)O layer and electrode material with high energy density would be 35 another (Ni-Cu)O layer. More precisely, the positional obtained. Therefore, the present inventors expected that Such relationship between the lithium atoms and the oxygen crystal could overcome the problem caused by using the atoms of (Ni-Cu)O layers is that the lithium atom corre known lithium nickel composite oxide as the positive elec sponds to the center of tetrahedron Sites having four oxygen trode active material of the Secondary battery Such as the atoms at each vertex. Namely, it can be said that the LiO above-mentioned LiNiO. 40 tetrahedron layer is formed. On the other hand, in the case With this point in mind, the present inventors examined of LiNiO, lithium atoms exist between NiO layers, so that various kinds of compounds and have found that the novel it can be said that the LiO octahedral structure is formed lithium nickel copper composite oxide, represented by considering the relationship between the positions of oxygen LiNiCuO (0.0peroxide, lithium sulfide, lithium ence 2C18). nitride, lithium fluoride, lithium chloride, lithium bromide, Originally, lithium atoms exist in an amount more than lithium iodide, lithium hydroxide, lithium nitrate, lithium two times as that of nickel atoms in LiNiCuO carbonate, lithium formate, lithium acetate, lithium (0.0ion-conductive material. At first, powders of LiNiCuO consisting of copper acetate, copper benzoate, copper(I) (0.0nitrogen, helium, neon, argon and krypton. Up to 0.1% of reduced and the battery is no more in practical use. H2O and/or CO contained in the inert gas as impurities does The positive electrode can be prepared by contact not affect the calcination. When the partial pressure of bonding the above mixture to a collector, or applying a oxygen in the calcination atmosphere is in the range of 0.0% slurry of the above mixture in a solvent such as N-methyl to 5.0% of the total pressure, it is possible to get the Single 45 2-pyrrollidone or the like to a collector followed by drying. phase of LiNiCuO (0.0tungsten dioxide, molybdenum dioxide, etc.). These phase layer of LiNiCuO (0.0water in the electrolytic copper) in the nickel compound and the copper compound solution is preferably 1,000 ppm or less, more preferably 2.0:1.0 to 2.5:1.0 and to make the molar ratio of nickel atom 100 ppm or less. In the alternative way, a dehydrated organic in the nickel compound:copper atom in the copper com Solvent and/or electrolyte may be used instead of dehydrat pound 0.99:0.01 to 0.01:0.99 and then calcining in an inert ing the organic electrolytic Solution. gas atmosphere or in an atmosphere of mixed gases of The nonaqueous Secondary battery of the present inven OXygen and the inert gas. tion may be prepared by connecting the above-mentioned The lithium nickel copper composite oxide of the present positive electrode and the collector with a first external invention contains two lithium atoms per one metal atom in terminal, by connecting the above-mentioned negative elec 35 trode and the collector with a Second external terminal and the crystal. If one of the lithium atoms is deserted from the then by interposing the above-mentioned ion-conductive crystal, Still another lithium atom remains in the crystal and material between these electrodes (the positive electrode and it can Sufficiently hold the crystal Structure. And in this case, the negative electrode). A separator Such as porous only 50% of the lithium atoms is deserted from the crystal. polyethylene, porous polypropylene or the like may also be Therefore, the change of the lattice volume itself is much 40 Smaller than the change of the lattice Volume in the case that interposed between these electrodes together with the ion one lithium atom is deserted from the crystal of LiCoO or conductive material, if necessary. The quality and the shape the like. Therefore, the lithium nickel copper composite of the Separator are not limited thereto. oxide can be provided as the positive electrode active Moreover, to prevent the first external terminal connected material of the nonaqueous Secondary battery having with the positive electrode and the Second external terminal 45 improved charge-discharge cycle life. connected with the negative electrode from contacting each The lithium nickel copper composite oxide of the present other, it is preferred that these external terminals are packed invention can be provided as the positive electrode active or hermetic Sealed with polypropylene, ethylene or the like. material of the nonaqueous Secondary battery having the These processes to prepare the battery are preferably carried capacity of about 250 mAh/g in the case that one of lithium out in an atmosphere of an inert gas or extremely dry air to 50 atoms is deserted, or the capacity of about 500 mAh/g in the prevent moisture from penetrating. Examples of the shape case that two of lithium atoms are deserted from the one for the nonaqueous Secondary battery of the present inven composition. Namely, the lithium nickel copper composite tion are, i.e., cylinder, button, Square, sheet and the like, but oxide of the present invention can be provided as the are not limited thereto. positive electrode active material of the nonaqueous Sec In accordance with an aspect of the present invention, 55 ondary battery having very large capacity. there is provided the novel lithium nickel copper composite Moreover, in the case of the lithium nickel copper com oxide having the compositional formula LiNiCuO posite oxide, relatively less expensive nickel and copper are (0.0lithium peroxide, lithium sulfide, lithium nitride, lithium fluoride, lithium chloride, lithium bromide, 65 EXAMPLES lithium iodide, lithium hydroxide, lithium nitrate, lithium In order to describe the present invention in detail, carbonate, lithium formate, lithium acetate, lithium Examples according to the present invention will follow, but 5,955,219 9 10 are not limited thereto and can be performed with modifi atmosphere was the mixed atmosphere of 5% of oxygen and cation which does not change the gist of the present inven 95% of nitrogen. The above-mentioned ratios of lithium tion. atom, nickel atom and copper atom in the Starting compo Example 1 sition (Li:Ni:Cu)=2.00:0.99:0.01, 2.00: 0.75:0.25, Samples were prepared by procedures hereinbelow. At 2.00:0.50:0.50, 2.00:0.25:0.75 and 2.00:0.01:0.99 corre first, LiO, NiO and CuO were weighed so as to make the spond in this order to samples A3a, A3b, A3c, A3d and A3e, molar ratio of lithium atom, nickel atom and copper atom respectively. The X-ray diffraction analyses of these Sample (Li:Ni:Cu)=2.00:0.99:0.01, 2.00:0.75:0.25, 2.00:0.50:0.50, were carried out in the same manner as that in Example 1. 2.00:0.25:0.75 and 2.00:0.01:0.99 and mixed in a mortar. According to the result of powder X-ray diffraction Struc The mixture was formed into pellets of 8 mm diameter and ture analyses, Valent number analyses of nickel by iodom 3 mm thickness by applying hydraulic pressure of 150 etry method and elementary analyses by ICP, it was found kg/cm thereto. These processes of weighing, mixing and that A3 a Was Liao Nioco Cuoio O2, A3b was preSSure molding were performed in dry air whose humidity Li2.ooNio,75Cuo.2sO2, A3c Was Li-ooNioso Cuoso O2, A3d was below 1%. Was Li2looNio.2s Cuo.7502 and A3e Was Li2.ooNiolo Cuo.o.oO2. Thus obtained pellets put on a ceramics boat was placed 15 in an electric furnace and then nitrogen gas was introduced Example 4 into the electric furnace. After full replacement of the Samples were prepared by using the same operations as in atmosphere in the oven by nitrogen gas, the temperature in above-mentioned Example 1 except that the calcination the electric furnace was raised from room temperature to temperature was 400° C. The above-mentioned ratios of 750° C. and the pellets were calcined at the constant lithium atom, nickel atom and copper atom in the Starting temperature of 750 C. for 12 hours. During raising and composition (Li:Ni:Cu)=2.00:0.99:0.01, 2.00:0.75:0.25, maintaining the temperature, nitrogen gas was also passed 2.00:0.50:0.50, 2.00:0.25:0.75 and 2.00:0.01:0.99 corre through at the rate of 2 liter/min. After cooling the electric spond in this order to Samples A4a, A4b, A4c, A4d and A4e, furnace to room temperature, the sample (calcined pellets) respectively. The powder of thus obtained Samples was dark was taken out. 25 green. The X-ray diffraction analyses of these Samples were The above-mentioned ratios of lithium atom, nickel atom carried out in the same manner as that in Example 1. and copper atom (Li:Ni:Cu)=2.00:0.99:0.01, 2.00:0.75:0.25, According to the result of powder X-ray diffraction Struc 2.00:0.50:0.50, 2.00:0.25:0.75 and 2.00:0.01:0.99 corre ture analyses, Valent number analyses of nickel by iodom spond in this order to Samples A1a, A1b, A1c, Ald and Ale, etry method and elementary analyses by ICP, it was found respectively. The powder X-ray diffraction patterns of these that A4a Was Liao Nioco Cuoio O2, A4b was Samples are shown in FIG. 4. AS X-ray Source, CukC.-rays Li2.ooNio,75Cuo.2sO2, A4c Was Li-ooNioso Cuoso O2, A4d of 2 kW output were used from target Cu enclosed tube. Was LiaooNios Cuo.750 and A4e Was LiaooNiolo Cuoloo,02. The X-ray diffraction pattern of each material had peaks with the diffraction angle 20 being in the range between Example 5 18.5° and 20.0, between 25.5 and 26.3°, between 32.0 35 Samples were prepared by using the same operations as in and 34.0, between 37.0 and 38.0°, between 38.0 and above-mentioned Example 1 except that the calcination 40.0, between 39.0 and 40.6, between 42.0 and 44.6, atmosphere was the atmosphere of argon gas. The above between 44.0 and 46.0, and between 48.0 and 50.0. mentioned ratioS of lithium atom, nickel atom and copper According to the result of powder X-ray diffraction Structure 40 atom in the starting composition (Li:Ni:Cu)=2.00:0.99:0.01, analyses, Valent number analyses of nickel by iodometry 2.00: 0.75:0.25, 2.00:0.50:0.50, 2.00:0.25: 0.75 and method and elementary analyses by ICP, it was found that 2.00:0.01:0.99 correspond in this order to samples A5a, A5b, that A1 a Was Liaoo Nioloo Cuoio O2, A1b was A5c, A5d and A5e, respectively. The powder of thus Li2.ooNio. 7s Cuo.2sO2, A1c Was Li2.ooNioso Cuoso O2, Ald obtained Samples was dark green. The X-ray diffraction Was Li2looNios Cuo.75 O2 and Ale Was Li2.ooNiolo Cuo.o.oO2. 45 analyses of these Samples were carried out in the same Example 2 manner as that in Example 1. Samples were prepared by using the same operations as in According to the result of powder X-ray diffraction Struc above-mentioned Example 1 except that the ratioS of lithium ture analyses, Valent number analyses of nickel by iodom atom, nickel atom and copper atom in the Starting compo etry method and elementary analyses by ICP, it was found sition were (Li:Ni:Cu=) 2.50:0.99:0.01, 2.50:0.75:0.25, 50 that A5 a was Liaoo Nioloo Cuoio O2, A5b was 2.50:0.50:0.50, 2.50:0.25:0.75 and 2.50:0.01:0.99. The Li2.ooNio.7sCuo.2502, A5c was LizooNioso CuosoC2, A5d above-mentioned ratioS of lithium atom, nickel atom and Was Li2looNio.2s Cuo.7502 and A5e Was Li2.ooNiolo Cuo.o.oO2. copper atom (Li:Ni:Cu)=2.50:0.99:0.01, 2.50:0.75:0.25, Example 6 2.50:0.50:0.50, 2.50:0.25:0.75 and 2.50:0.01:0.99 corre spond in this order to Samples A2a, A2b, A2c, A2d and A2e, 55 Samples were prepared by using the same operations as in respectively. The X-ray diffraction analyses of these Samples above-mentioned Example 1 except that LiO, Ni(OH) and were carried out in the same manner as that in Example 1. Cu(OH)2 were used as starting materials. The above According to the result of powder X-ray diffraction Struc mentioned ratioS of lithium atom, nickel atom and copper ture analyses, Valent number analyses of nickel by iodom atom in the starting composition (Li:Ni:Cu)=2.00:0.99:0.01, etry method and elementary analyses by ICP, it was found 60 2.00: 0.75:0.25, 2.00:0.50:0.50, 2.00:0.25: 0.75 and 2.00:0.01:0.99 correspond in this order to samples A6a, A6b, that A2a was Liaoo Nioloo Cuoio O2, A2b was A6c, A6d and A6e, respectively. The powder of thus Li2.ooNio. 7s Cuo.2502, A2c was Lidoo Nioso Cuoso O2, A2d obtained Samples was dark green. The X-ray diffraction Was Li2looNios Cuo.75 O2 and A2e Was Li2.ooNiolo Cuo.o.oO2. analyses of these Samples were carried out in the same Example 3 65 manner as that in Example 1. Samples were prepared by using the same operations as in According to the result of powder X-ray diffraction Struc above-mentioned Example 1 except that the calcination ture analyses, Valent number analyses of nickel by iodom 5,955,219 11 12 etry method and elementary analyses by ICP, it was found The X-ray diffraction patterns of these Samples are shown that A6 a Was Liao Nioco Cuoio O2, A6 b was in FIG. 6. According to the result of powder X-ray diffrac Li2.ooNio. 7s Cuo.2sO2, A6c Was Li2.ooNioso Cuoso O2, A6d tion Structure analyses and elementary analyses by ICP, it Was Li2looNios Cuo.75 O2 and A6e Was Li2.ooNiolo Cuo.o.oO2. was found that each of the samples B3a, B3b, B3c, B3d and B3e was a mixture of Li2CuO and Starting material of Li2O Example 7 and NiO. Samples were prepared by using the same operations as in above-mentioned Example 1 except that the calcination time Comparative Example 4 was one hour. The above-mentioned ratioS of lithium atom, Samples were prepared by using the same operations as in nickel atom and copper atom in the Starting composition above-mentioned Example 1 except that the ratio of lithium (Li:Ni:Cu)=2.00:0.99:0.01, 2.00:0.75:0.25, 2.00:0.50:0.50, atom, nickel atom and copper atom in the Starting compo 2.00:0.25:0.75 and 2.00:0.01:0.99 correspond in this order sition were (Li:Ni:Cu=) 2.55:0.99:0.01, 2.55:0.75:0.25, to samples A7a, A7b, A7c, A7d and A7e, respectively. The 2.55:0.50:0.50, 2.55:0.25:0.75 and 2.55:0.01:0.99. The X-ray diffraction analyses of these samples were carried out above-mentioned ratioS of lithium atom, nickel atom and in the same manner as that in Example 1. 15 copper atom in the starting composition (Li:Ni:Cu)= According to the result of powder X-ray diffraction Struc 2.55: 0.99: 0.01, 2.55:0.75:0.25, 2.55:0.50:0.50, ture analyses, Valent number analyses of nickel by iodom 2.55:0.25:0.75 and 2.55:0.01:0.99 correspond in this order etry method and elementary analyses by ICP, it was found to samples B4a, B4b, B4c, B4d and B4e, respectively. The that A7 a Was Liaoo Nioloo Cuoio O2, A7b was X-ray diffraction analyses of these Samples were carried out Li2.ooNio. 7s Cuo.2502, A7c was Lidoo Nioso Cuoso O2, A7d in the same manner as that in Example 1. Was Li2looNios Cuo.75 O2 and A7e Was Li2.ooNiolo Cuo.o.oO2. According to the result of powder X-ray diffraction Struc Comparative Example 1 ture analyses and elementary analyses by ICP, it was found that B4a was a mixture of LiaooNioloo Cuoio O2 and Li2O, Samples were prepared by using the same operations as in 25 B4b was a mixture of Liaonios Cuos O and Li2O, B4c above-mentioned Example 1 except that the calcination was a mixture of LiaooNioso Cuoso O2 and Li2O, B4d was a atmosphere was the mixed atmosphere of 7.5% of oxygen mixture of Liaonios Cuo.750 and Li2O and B4e was a and 92.5% of nitrogen. The above-mentioned ratios of mixture of Li2.ooNiolo Cuo.o.oO2 and Li2O. lithium atom, nickel atom and copper atom (Li:Ni:Cu) in the starting composition=2.00:0.99: 0.01, 2.00:0.75:0.25, Comparative Example 5 2.00:0.50:0.50, 2.00:0.25:0.75 and 2.00:0.01:0.99 corre spond in this order to samples B1a, B1b, B1c, B1d and B1e, Samples were prepared by using the same operations as in respectively. The X-ray diffraction analyses of these Samples the preparation of the Samples mentioned in Example 1 were carried out in the same manner as that in Example 1. except that the ratio of lithium atom, nickel atom and copper The X-ray diffraction patterns of these samples are shown atom in the starting composition were (Li:Ni:Cu=) in FIG. 5. According to the result of powder X-ray diffrac 35 1.95:0.99: 0.01, 1.95: 0.75:0.25, 1.95:0.50:0.50, tion Structure analyses and elementary analyses by ICP, it 1.95:0.25:0.75 and 1.95:0.01:0.99. The above-mentioned ratioS of lithium atom, nickel atom and copper atom in the was found that each of the samples B1a, B1b, B1c, B1d and starting composition (Li: Ni: Cu)= 1.95:0.99: 0.01, B1e was a mixture of LiCuO and LiNiO like compound 1.95:0.75:0.25, 1.95:0.50:0.50, 1.95:0.25:0.75 and that have rock Salt type Structure. 40 1.95:0.01:0.99 correspond in this order to samples B5a, B5b, Comparative Example 2 B5c, B5d and B5e, respectively. The X-ray diffraction analyses of these Samples were carried out in the same Samples were prepared by using by the Same operations manner as that in Example 1. as in above-mentioned Example 1 except that the calcination According to the result of powder X-ray diffraction Struc temperature was 350° C. The above-mentioned ratios of 45 lithium atom, nickel atom and copper atom in the Starting ture analyses and elementary analyses by ICP, it was found composition (Li:Ni:Cu)=2.00:0.99:0.01, 2.00:0.75:0.25, that B5a was a mixture of LiNicoCuo O and NiO, 2.00:0.50:0.50, 2.00:0.25:0.75 and 2.00:0.01:0.99 corre B5b was a mixture of Liaonio. 7s Cuos O and NiO, B5c spond in this order to samples B2a, B2b, B2c, B2d and B2e, was a mixture of LiNisoCuoso O and NiO, B5d was a respectively. The X-ray diffraction analyses of these Samples 50 mixture of Liaonios Cuo.70 and NiO and B5e was a were carried out in the same manner as that in Example 1. mixture of LiaooNiolo Cuoco O2 and CuO. According to the result of powder X-ray diffraction Struc Comparative Example 6 ture analyses and elementary analyses by ICP, it was found that each of the samples B2a, B2b, B2c, B2d and B2e was Samples were prepared by using the same operations as in a mixture containing two or more of the Starting materials 55 above-mentioned Example 6 except that the calcination time LiO, NiO and CuO. was one hour. The above-mentioned ratioS of lithium atom, nickel atom and copper atom (Li:Ni:Cu)=2.00:0.99:0.01, Comparative Example 3 2.00: 0.75:0.25, 2.00:0.50:0.50, 2.00:0.25: 0.75 and Samples were prepared by using the same operations as in 2.00:0.01:0.99 correspond in this order to samples B6a, B6b, above-mentioned Example 1 except that the calcination 60 B6c, B6d and B6e, respectively. The X-ray diffraction temperature was 800° C. The above-mentioned ratios of analyses of these Samples were carried out in the same lithium atom, nickel atom and copper atom (Li:Ni:Cu) in the manner as that in Example 1. starting composition=2.00:0.99: 0.01, 2.00:0.75:0.25, According to the result of powder X-ray diffraction Struc 2.00:0.50:0.50, 2.00:0.25:0.75 and 2.00:0.01:0.99 corre ture analyses, Valent number analyses of nickel by iodom spond in this order to samples B3a, B3b, B3c, B3d and B3e, 65 etry method and elementary analyses by ICP, it was found respectively. The X-ray diffraction analyses of these Samples that each of the samples B6a, B6b, B6c, B6d and B6e was were carried out in the same manner as that in Example 1. a mixture of LiO, Ni(OH) and Cu(OH). 5,955,219 13 14 Phases of samples in Examples 1 to 7 and Comparative was contact-bonded was used. Used as the liquid electrolyte Examples 1 to 6 are shown in Table 1. 7 was the solution in which 1 mol/liter of lithium perchlorate (LiCIO) was dissolved in the solvent mixture containing 50 TABLE 1. vol % of ethylene carbonate and 50 vol % of diethylene carbonate. The battery was fabricated by putting these Example 1 Comparative Example 1 positive electrode 4, negative electrode 6, counter electrode A1a LiNiogoCuoioiO2 B1a LiNiO, 4 and liquid electrolyte 7 into the glass cell 1 as shown in A1b Li2Nio. 7s Cuo.2sO2 B1b LiCuO + LiNiO2 + LiO FIG. 7 and the charge-discharge test of the resulting battery A1c Li2Nioso CuosoO2 B1c LiCuO + LiNiO, was performed. All these processes were carried out in the A1d Li2Nio.2sCuo.7sO2 B1d LiCuO + LiNiO, A1e LiNiolo CuogoO2 B1e LiCuO glove box filled with argon gas. Example 2 Comparative Example 2 The charge-discharge test of the battery thus constituted A2a LiNiogoCuoioiO2 B2a. LiO + NiO was performed at the constant current in the range of 1.5 V A2b Li2Nio. 7s Cuo.2sO2 B2b LiO + NiO + CuO to 4.2 V. For all samples A1a to Ale, the above-mentioned A2c Li2Nioso CuosoO2 B2c LiO + NiO + CuO tests were performed. Table 2 shows the charge capacities A2d Li2Nio.2sCuo.7sO2 B2d LiO + NiO + CuO 15 and discharge capacities of the Samples in the first cycle. The A2e LiNiolo CuogoO2 B2e LiO + CuO charge capacity of the first charge for the electrode using the Example 3 Comparative Example 3 Sample A1a as the positive electrode active material was A3a Li2NiogoCuoioiO2 B3a LiO + NiO about 384 mAh/g. And the capacity of the first discharge for A3b Li-Nio. 7s Cuo.25C2 B3b LiCuO + NiO + LiO that electrode was about 368 mAh/g. The capacity of the first A3c Li2Nioso CuosoO2 B3c LiCuO + LiNiO, charge corresponded to the fact that about 1.5 of lithium A3d Li2Nio.2sCuo.7sO2 B3d LiCuO + LiCuO A3e Li2Niolo CuogoO2 B3e LiCuO + LiCuO atoms were deserted from the crystal of LiNiCuO Example 4 Comparative Example 4 (0.0lead, 5 represents a positive electrode, 6 repre Samples A1a to Ale, the above-mentioned tests were per Sents a negative electrode, 4 represents a counter electrode formed. Table 3 shows the charge capacities and discharge and 7 represents an liquid electrolyte. The positive electrode capacities of the Samples in the first cycle. It was found that 5 was connected to the lead 3a and the negative electrode 6 55 the batteries in accordance with Example 9 and these in the was connected to the lead 3c. The chemical energy generated accordance with Example 8 showed almost the same results, inside the battery could be taken out from the ends of leads which meant that the battery had great capacity and large 3a and 3C as the electrical energy. charge and discharge efficiency. One of the Samples A1a, A1b, A1c, Ald and Ale was Example 10 ground in the mortar, mixed with about 10 wt % of acetylene 60 black as the electron conducting material followed by mix FIG. 8 shows the schematic illustration of the coin-type ing with about 10 wt % of Teflon resin powder as the binder. battery in accordance with the present invention. In FIG. 8, The mixture was molded with pressure in the tablet molder reference numeral 8 represents a positive electrode can, 9 and formed into the pellets. The positive electrode 5 was represents a positive electrode collector, 14 represents a prepared by contact-bonding the pellets to the metal mesh. 65 positive electrode, 10 represents a negative electrode can, 11 AS the negative electrode 6 and the counter electrode 4, represents a negative electrode collector, 15 represents a used was the nickel mesh on which the metallic lithium sheet negative electrode, 12 represents a packing and 13 repre 5,955,219 15 16 Sents a separator. The positive electrode 14 and the negative electrode 15 were placed inside the coin-type cell consti TABLE 2 tuted with the positive electrode can 8 and the negative charge capacity discharge capacity electrode can 10 facing each other, with the separator 13 (mAh/g) (mAh/g) efficiency (%) disposed in between impregnated with the liquid electrolyte. Ala 384.6 368.1 95.7 Accordingly, the positive electrode 14 was connected to Alb 312.6 288.4 92.3 Alc 306.0 288.2 94.2 the positive electrode can 8 via the positive electrode Ald 299.8 273.6 91.3 collector 9, and the negative electrode 15 was connected to Ale 293.4 259.0 88.3 the negative electrode can 10 via the negative electrode collector 11. The chemical energy generated inside the battery could be taken out from the ends of the positive electrode can 8 and the negative electrode can 10 as the TABLE 3 electrical energy. charge capacity discharge capacity One of the Samples A1a, A1b, A1c, Ald and Ale was 15 (mAh/g) (mAh/g) efficiency (%) ground in the mortar, mixed with about 50 wt % of acetylene Ala 295.4 290.3 98.3 black as the conductive material followed by mixing with Alb 290.7 289.9 99.7 about 1 wt % of Teflon resin powder as the binder. The Alc 281.0 275.5 98.0 mixture was molded with pressure in the tablet molder and Ald 278.2 273.O 98.1 formed into pellets. The positive electrode 14 was prepared Ale 265.6 260.3 98.0 by contact-bonding the pellets to the metal mesh. Carbon material which was derived from pitch by ther molysis in the inert gas atmosphere was mixed with about 1 TABLE 4 wt % of Teflon resin powder as the binder. As the negative 25 charge capacity discharge capacity electrode 15, were used pellets formed from the mixture by (mAh/g) (mAh/g) efficiency (%) molding with pressure in the tablet molder. Used as the Ala 353.4 350.6 99.2 liquid electrolyte was the solution in which 0.5 mol/liter of Alb 351.6 348.6 99.1 lithium phosphofluoride (LiPF) was dissolved in the sol Alc 349.8 346.3 99.0 vent mixture containing 10 Vol % of propylene carbonate Ald 347.0 343.3 98.9 and 90 vol% of tetrahydrofuran. Ale 343.4 338.9 98.7 The coin-type battery was fabricated by putting these positive electrode 14, negative electrode 15 and electrolytic solution 16 into the coin-type cell as shown in FIG. 8 and TABLE 5 charge-discharge tests of the resulting coin-type battery 35 charge capacity discharge capacity were performed. For all Samples A1a to Ale, the above (mAh/g) (mAh/g) efficiency (%) mentioned tests were performed. All processes were carried out in a glove box filled with argon gas. Table 4 shows the LiNiO, 165.5 140.7 85.1 charge capacities and discharge capacities of the Samples in the first cycle. The batteries in accordance with Example 10 40 According to the present invention, the novel compound and these in accordance with Example 8 showed almost the LiNiCuO(0.0