Silicon oxide based high capacity anode materials for lithium ion batteries
Silicon oxide based materials, including composites with various electrical conductive compositions, are formulated into desirable anodes. The anodes can be effectively combined into lithium ion batteries with high capacity cathode materials. In some formulations, supplemental lithium can be used to stabilize cycling as well as to reduce effects of first cycle irreversible capacity loss. Batteries are described with surprisingly good cycling properties with good specific capacities with respect to both cathode active weights and anode active weights.
1. A lithium ion battery comprising a positive electrode comprising a lithium metal oxide, a negative electrode, a separator between the positive electrode and the negative electrode, and an electrolyte comprising lithium ions and from about 5 volume percent to about 18 volume percent halogenated carbonate, wherein the negative electrode comprises particulate silicon oxide based active material comprising a silicon oxide carbon composite composition, wherein the silicon oxide carbon composite composition comprises silicon oxide having an amorphous carbon coating and is preloaded with lithium within the active material in a particulate form with no additional supplemental lithium in the battery at assembly, and wherein the negative electrode further comprises from about 1 weight percent to about 30 weight percent electrically conductive additive comprising graphite powder and carbon black.
2. The lithium ion battery of claim 1 wherein the negative electrode comprises silicon oxide with the structure of SiO x , 0.1≤x≤1.5.
3. The lithium ion battery of claim 1 wherein the halogenated carbonate comprises fluoroethylene carbonate, fluorinated vinyl carbonate, monochloro ethylene carbonate, monobromo ethylene carbonate, 4-(2,2,3,3-tetrafluoropropoxymethyl)-[1,3]dioxolan-2-one, 4-(2,3,3,3-tetrafluoro-2-trifluoro methyl-propyl)-[1,3]dioxolan-2-one, 4-trifluoromethyl-1,3-dioxolan-2-one, bis(2,2,3,3-tetrafluoro-propyl) carbonate, bis(2,2,3,3,3-pentafluoro-propyl) carbonate, or mixtures thereof.
4. The lithium ion battery of claim 1 wherein the halogenated carbonate comprises fluoroethylene carbonate, and wherein the negative electrode has a specific discharge capacity of at least about 700 mAh/g at a rate of C/3 based on negative electrode active material mass.
5. The lithium ion battery of claim 1 wherein the particulate silicon oxide based active material is preloaded with the lithium to at least about 10% of a negative electrode capacity.
6. The lithium ion battery of claim 1 wherein the lithium metal oxide comprises LiCoO 2 .
7. The lithium ion battery of claim 1 wherein the lithium metal oxide comprises LiMO 2 , where M is one or more metals with an average oxidation state of +3.
8. The lithium ion battery of claim 1 wherein the lithium metal oxide is represented by the formula Li 1+b Ni α Mn β Co γ A δ O 2-z F z , where b ranges from about 0.01 to about 0.3, α ranges from about 0 to about 0.4, β ranges from about 0.2 to about 0.65, γ ranges from 0 to about 0.46, δ ranges from 0 to about 0.15 and z ranges from 0 to about 0.2 with the proviso that both α and γ are not zero, and where A is Mg, Sr, Ba, Cd, Zn, Al, Ga, B, Zr, Ti, Ca, Ce, Y, Nb, Cr, Fe, V, Li or combinations thereof.
9. The lithium ion battery of claim 1 wherein the particulate silicon oxide based active material is preloaded with the lithium by contacting the particulate silicon oxide based active material with electrolyte and a lithium source.
10. The lithium ion battery of claim 9 where the lithium source comprises elemental lithium.
11. The lithium ion battery of claim 1 wherein the particulate silicon oxide based active material is preloaded with the lithium by forming an electrode with the particulate silicon oxide based active material and placing the electrode in a vessel containing electrolyte and a sheet of lithium source material contacting the electrode.
12. The lithium ion battery of claim 1 wherein the silicon oxide carbon composite composition comprises up to 60 wt % graphite.
13. The lithium ion battery of claim 1 wherein the silicon oxide carbon composite composition comprises from 5 wt % to 55 wt % graphite.
14. The lithium ion battery of claim 1 wherein the silicon oxide carbon composite composition comprises from 30 wt % to 45 wt % graphite.
15. The lithium ion battery of claim 1 wherein the negative electrode further comprises polyimide.
16. The lithium ion battery of claim 1 wherein the negative electrode further comprises a binder having an elongation of at least about 50% and a tensile strength of at least about 100 MPa.
17. The lithium ion battery of claim 1 wherein the battery discharge capacity decreases by no more than about 15 percent at a 50th discharge cycle relative to a 7th discharge cycle when discharged at a rate of C/3 from a 7th discharge to a 50th discharge.
18. The lithium ion battery of claim 1 wherein the particulate silicon oxide based active material has a density of at least about 0.6 g/cm 3 .
19. The lithium ion battery of claim 1 wherein the negative electrode has an average dried thickness of at least about 25 microns and a loading of the particulate silicon oxide based active material of at least about 2 mg/cm 2 .
20. The lithium ion battery of claim 19 wherein the negative electrode exhibits a capacity per unit area of at least about 3.5 mAh/cm 2 .