US 2015 0000118A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2015/0000118A1 ZHAO et al. (43) Pub. Date: Jan. 1, 2015 (54) METHOD FOR MANUFACTURING (52) U.S. Cl. GRAPHENE-INCORPORATED CPC ..................................... H0IM 10/04 (2013.01) RECHARGEABLE L-ION BATTERY USPC ......................... 29/623.3; 29/623.1; 29/623.5 (71) Applicants:XIN ZHAO, New York, NY (US); (57) ABSTRACT Minjie Li, New York, NY (US) A method for manufacturing a graphene-incorporated rechargeable Li-ion battery discloses a graphene-incorpo (72) Inventors: XIN ZHAO, New York, NY (US); rated rechargeable Li-ion battery with enhanced energy and Minjie Li, New York, NY (US) power delivery abilities. The method comprises the steps (a) fabricating a high-performance anode film based on graphene or graphene hybrid; (b) introducing a desired amount of (21) Appl. No.: 13/927,125 lithium into the anode material to produce a prelithiated graphene-based anode; (c) constructing a full cell utilizing a (22) Filed: Jun. 26, 2013 cathode film and the prelithiated anode film. The graphene based anodes incorporating exfoliated graphene layers over Publication Classification come the large irreversible capacity and initial lithium ion consumption upon pre-lithiation, and demonstrate remark (51) Int. Cl. ably enhanced specific capacity and rate capability over con HIM I/04 (2006.01) ventional anodes. Patent Application Publication Jan. 1, 2015 Sheet 1 of 4 US 2015/0000118A1 Figure 1A Figure 1B 20 Figure 2. Patent Application Publication Jan. 1, 2015 Sheet 2 of 4 US 2015/0000118A1 Graphene nanoplatelet Partially oxidized GP Molecule intercalation Further exfoliation Xaaaaad Wash and dry Partially oxidized few-layer Gnp Mixing with conductive additive and binder Formulated Gnp anode Lithiation Prelithiated Gnp anode Figure 3. Patent Application Publication Jan. 1, 2015 Sheet 3 of 4 US 2015/0000118A1 a. s s & 5 400 : GraphiteInte 90 5 2 * Partially oxidized (in P 8.5% 80 2 300 g a 70 200 60 as39 5 100 50 2. O 40 E A. () ( 20 30 40 50 60 O Cycle Number Figure 4 - - 5 glyphile 5 w traplits G we thartially oxidized Ge.n won Partially"...alla xidized Gap- 21.0 2 1.0 t 1st Cycle t 5th Cycle 0.5 of 0.5 Ss S.s > 0.0 > ().) ...essessex O 200 40t) 600 800 () 100 2) 300 400 Specific Capacity (mAh/g) Specific Capacity (mAh/g) Figure 5 Patent Application Publication Jan. 1, 2015 Sheet 4 of 4 US 2015/0000118A1 8 o 8 8 c. 8 e e g o e 100 6 Grace Prelitiated Gri Panode 8O e o O e o e o 60 40 2 20 O4 0 O O O. O 2 4 6 8 10 2 14 Cycle Number Figure 6. - - syon 4.0 s:s 4.0 a 3.5 3.5 ga > 3.0Fr. e so3.0 C12 You' 2.5 wn NC- 2.5 4m Ny wer S.r.little s about Nritt isar 2.0 ae 2.0 () 3 4 5 () 2 3. 4. 5 Capacity (mAh) Capacity (mAh) Figure 7. US 2015/0000118A1 Jan. 1, 2015 METHOD FOR MANUFACTURING to electrolyte. Nevertheless, these processes kill the intrinsic GRAPHENE-INCORPORATED advantageous features of graphene anode such as high spe RECHARGEABLE L-ION BATTERY cific surface area and Li ion diffusivity, which sacrifices the reversible capacity and rate capability of graphene anode. FIELD OF THE INVENTION 0005. Another common practice to address this issue is to load excess cathode material when assembling Li-ion batter 0001. The present invention relates to Li-ion batteries, and ies, so that the loss of Li ions during the initial cycles can be in particular to a method for manufacturing a graphene-in compensated by the excess Li ions introduced by cathode. corporated rechargeable Li-ion battery However, such method results in a battery cell having cathode and anode which are stoichiometrically unbalanced. The BACKGROUND OF THE INVENTION excess cathode material adds the weight and cost of the cell, 0002 Safety concerns over utilization of pure metallic and may lead to internal shorts, combustible gas generation lithium foils as negative electrodes for rechargeable lithium and thus catastrophic failure if the excess lithium is deposited ion batteries have led to the development of carbonaceous non-uniformly on the anode or isolated from both electrodes materials as alternative anode. Conventional Li-ion batteries (Referring to G. -A. Nazri and B. J. Howie, Method for comprise a primary graphite as a carbonaceous anode in Manufacturing Lithium-Deactivated Carbon Anodes, Euro conjunction with a lithium-containing metal oxide, for pean Patent EP 96201589.7.). example, lithium cobalt oxide (LiCoO2) and lithium manga nese oxide (LiMn2O4) as a cathode. Upon ideal charge/dis SUMMARY OF THE INVENTION charge reactions, lithium ions are intercalated and de-inter 0006. Accordingly, the object of the present invention is to calated between the stacked graphene layers reversibly, provide a method for manufacturing a graphene-incorporated yielding 100% charge/discharge efficiency. The resulting gra rechargeable Li-ion battery, wherein the battery has enhanced phitic compound intercalated with lithium ions may be power Supply ability and quick delivery of the charges. There expressed as LixC6, where x is typically less than 1 for fore the invention describes a design of graphene-incorpo well-ordered graphite without significant turbostratic disor rated rechargeable Li-ion batteries and overcomes the afore dering. This corresponds to a theoretical specific capacity of mentioned problems by prelithiating the graphene-based 372 mAh/g (x=1, e.g. LiC6). In order to minimize capacity electrodes. reduction due to this replacement, X in LixC6 must be maxi 0007. The battery cell contains a graphene-incorporated mized, and the irreversible capacity loss due to side reactions anode preloaded with appropriate amount of lithium, which is in the initial cycles must be minimized. positioned opposite a cathode. The anode and cathode is 0003 Graphene is considered a promising electrode mate physically separated by a non-aqueous ionic conductor in rial toward Li-ion batteries with high power and energy deliv liquid, Solid or gel format. ery, attributed to its high conductivity and high Surface area 0008. The approach of the present invention comprises (a) without pore tortuosity. The large specific Surface area, abun fabricating a high-performance anode film based on graphene dant edge planes and defects of graphene, as well as micro or graphene hybrid; (b) introducing a desired amount of cavities and pores present between rearranged graphene crys lithium into the anode film to produce a prelithiated tallites provide excess Li ion binding and storage sites graphene-based anode film; (c) constructing a full cell utiliz compared with conventional graphitic anodes (see FIGS. 1A ing a cathode film and the prelithiated graphene-based anode and 1B). FIGS. 1A and 1B show a structural model of an film. The graphene-based anodes incorporating pristine or ordered graphitic carbon (1A) and a disordered graphene functionalized graphene layers demonstrate remarkably stacks (1B). Pronounced improvement of reversible capacity enhanced specific capacity and rate capability over conven has therefore been demonstrated in graphene anode, and very tional graphitic anode (referring to FIG. 3), offering possi large reversible capacity up to 740 mAh/g (composition of bilities to achieve unprecedented combinations of energy and LiC3) can be envisioned. Besides, lithium intercalation into power output for high-performance Li-ion batteries. Lithiat graphene is not limited by the kinetics of lithium staging ing the graphene-based anodes prior to battery cell assembly reactions within conventional graphitic anodes. The high Li eliminates the Li ion consumption associated with the irre ion diffusivity and electrical conductivity greatly accelerates versible reactions of graphene efficiently, and the cells attain the kinetics of charge-transfer and diffusion reactions of improved electrode utilization, capacity retention and cycling graphene anode, which can therefore operate at very high efficiency with minimized safety hazards during operation. charge/discharge rates while retaining a high capacity. 0009 Lithiation of anode materials in a prior art Li-ion 0004. However, irreversible reactions usually occur inten battery usually induces a large Volumetric expansion to the sively in graphene anode when contacting with electrolyte. active particles and electrode films, for example 300-400% of This is caused by the large Surface area of irregular plates and its original dimension of silicon particle or thin film (see Ref. direct exposure of highly active edge planes of graphene 2). Such highly lithiated particles or films are extremely layers. The irreversible consumption of Li ions in the initial brittle and prone to pulverization or fragmentation during cycles leads to deficiency of Li ions in the battery cell and Successive charge/discharge cycling. These two issues can be destruction of original anode structures, and Subsequent significantly mitigated by the incorporation of graphene in capacity fading is evitable. To Suppress the irreversible reac the anode formation. First, the Small size and mechanical tions of Li ions with carbonaceous materials, the carbon flexibility of graphene sheets can readily accommodate any aceous particles are usually subjected to grinding and reas Li ion insertion/extraction stress and Volume variation, rep sembly to obtain a smooth Surface, or high-temperature resenting a highly stable lithium-retentive anode system that graphitization processes to eliminate structural disordering. can be coupled with lithium-free cathode materials to con Further irreversible reactions associated with edge planes can struct full battery cells (Ref.3). Such graphene-based anodes be reduced by coating the particles to prevent direct exposure with superb tolerance to structural deformation also provide a US 2015/0000118A1 Jan. 1, 2015 robust matrix to Support or incorporate other high-capacity ing a cathode film and the prelithiated graphene-based anode active species Such as metal and intermetallic alloys, which film.