Electrolytes for rechargeable batteries
First Claim
1. A lithium ion battery comprising:
- an electrode comprising an electrochemically active material selected from the group consisting of a silicon containing material, a tin containing material, a germanium containing material, and an aluminum containing material;
an electrolyte comprising a lithium containing salt, a pyrocarbonate, and one or more fluorinated carbonate solvents;
and a solid electrolyte interphase (SEI) layer that includes fluorine, wherein the electrode comprising an electrochemically active material includes core-shell nanostructures that include an inner shell and an outer shell; and
wherein the SEI layer is formed on the outer shell, the nanostructures having at least one cross-sectional dimension between 1 and 1000 nm.
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Accused Products
Abstract
Provided are novel electrolytes for use in rechargeable lithium ion cells containing high capacity active materials, such as silicon, germanium, tin, and/or aluminum. These novel electrolytes include one or more pyrocarbonates and, in certain embodiments, one or more fluorinated carbonates. For example, dimethyl pyrocarbonate (DMPC) may be combine with mono-fluoroethylene carbonate (FEC). Alternatively, DMPC or other pyrocarbonates may be used without any fluorinated carbonates. A weight ratio of pyrocarbonates may be between about 0% and 50%, for example, about 10%. Pyrocarbonates may be combined with other solvents, such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and/or ethyl-methyl carbonate (EMC). Alternatively, pyrocarbonates may be used without such solvents. Experimental results conducted using electrochemical cells with silicon based electrodes demonstrated substantial improvements in cycle life when pyrocarbonate containing electrolytes were used in comparison with pyrocarbonate free electrolytes.
84 Citations
23 Claims
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1. A lithium ion battery comprising:
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an electrode comprising an electrochemically active material selected from the group consisting of a silicon containing material, a tin containing material, a germanium containing material, and an aluminum containing material; an electrolyte comprising a lithium containing salt, a pyrocarbonate, and one or more fluorinated carbonate solvents; and a solid electrolyte interphase (SEI) layer that includes fluorine, wherein the electrode comprising an electrochemically active material includes core-shell nanostructures that include an inner shell and an outer shell; and
wherein the SEI layer is formed on the outer shell, the nanostructures having at least one cross-sectional dimension between 1 and 1000 nm. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 12, 13, 14, 15, 21, 22, 23)
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10. The lithium ion battery 1, wherein the electrolyte comprises one or more pyrocarbonates that have a total concentration in the electrolyte of less than about 50% by weight.
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11. The lithium ion battery 1, wherein the electrolyte comprises one or more pyrocarbonates that have a total concentration in the electrolyte of between about 1% and 10% by weight.
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16. A lithium ion battery electrolyte for use in a lithium ion battery containing high capacity active materials, the lithium ion battery electrolyte comprising:
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a lithium containing salt; a solvent substantially free from linear carbonates; dimethyl pyrocarbonate (DMPC); and one or more fluorinated carbonate solvents substantially free from linear carbonates, wherein the DMPC is present in the lithium battery electrolyte at a concentration between 5% and 10% by weight and wherein the one or more fluorinated carbonates are present in the lithium ion battery electrolyte at a concentration of between about 1% and 10% by weight. - View Dependent Claims (17, 18, 19, 20)
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Specification