SILICON ANODE BASED LITHIUM-ION BATTERY
Silicon-polymer composite anodes; a method for producing the anodes; and dual salt electrolytes to improve the conductivity, specific capacity, rate capability, and stability of the anodes; suitable for use in electrochemical energy storage devices are disclosed.
1 . A method of making an anode for an electrochemical energy storage device, the process comprising:
a) mixing silicon particles and at least one polymer to form a mixture;
b) coating the mixture onto a copper current collector to form a coated copper current collector; and
c) subjecting the coated copper current collector to a temperature treatment to form the anode.
2 . The method of claim 1 , wherein subjecting the coated copper current collector to the temperature treatment comprises heating the coated copper current collector in an inert atmosphere to a temperature in the range of from about 200° C. to about 600° C.
3 . The method of claim 1 , further comprising: after step a) and before step b), adding a solvent to the mixture to disperse the silicon particles and the at least one polymer, the solvent being selected from the group consisting of N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), dimethyl sulfone (DMSO 2 ), dimethyl sulfoxide (DMSO), N—N-dimethyl acetamide (DMAc), ethylene carbonate (EC), and propylene carbonate (PC).
4 . The method of claim 3 , further comprising: after step b) and prior to step c), removing the solvent from the mixture coated on the copper current collector.
5 . The method of claim 3 , wherein step c) removes the solvent from the mixture coated on the copper current collector.
6 . The method of claim 1 , wherein the silicon particles range in size from about 1 nm to about 100 μm.
7 . The method of claim 1 , wherein the mixture comprises one or more carbonaceous material.
8 . The method of claim 7 , wherein the one or more carbonaceous material is chosen from graphite, hard-carbon, tin, and germanium particles mixed with active material silicon particles.
9 . The method of claim 1 , wherein the mixture comprises from 10 to 80% by weight silicon particles.
10 . The method of claim 1 , wherein the anode comprises from 10 to 40% by weight of polymer.
11 . The method of claim 1 , wherein the at least one polymer comprises polyacrylonitrile (PAN).
12 . The method of claim 1 , wherein the silicon particles comprise silicon composite particles.
13 . A dual-salt electrolyte, comprising:
(a) LiPF 6 and LiFSI lithium salts in the range of from 10 to 30 wt. % of the electrolyte;
(b) an aprotic organic solvent system containing fluoroethylene carbonate in the range of from 10 to 30 wt. % of the electrolyte; and
(c) at least one additive.
14 . The electrolyte of claim 13 , wherein the aprotic organic solvent system comprises an open-chain or cyclic carbonate, carboxylic acid ester, nitrite, ether, sulfone, ketone, lactone, dioxolane, glyme, crown ether, siloxane, phosphoric acid ester, phosphite, mono- or polyphosphazene or mixtures thereof.
15 . The electrolyte of claim 13 , wherein the aprotic organic solvent system is present in a concentration of from 40 to 90 wt. % of the electrolyte.
16 . The electrolyte of claim 13 , wherein the at least one additive is a compound containing at least one unsaturated carbon-carbon bond, carboxylic acid anhydrides, sulfur-containing compounds, phosphorus-containing compounds, boron-containing compounds, silicon-containing compounds, nitrogen-containing compounds, or mixtures thereof.
17 . The electrolyte of claim 13 , wherein the at least one additive is present in a concentration of from 0.1 to 5 wt. % of the electrolyte.
18 . An anode comprising:
a current collector coated with a plurality of active material particles, wherein each of the plurality of active material particles has a particle size of between about 1 nm and about 100 μm, and at least one polymer, wherein the plurality of active material particles is enclosed by the at least one polymer.
19 . An electrochemical energy storage device comprising:
an anode comprising: a plurality of active material particles, wherein each of the plurality of active material particles has a particle size of between about 1 nm and about 100 μm, and at least one polymer, wherein the plurality of active material particles is enclosed by the at least one polymer;
a cathode; and
a dual-salt electrolyte comprising: LiPF 6 and LiFSI lithium salts, an aprotic organic solvent system containing at least one solvent comprising fluoroethylene carbonate, and at least one additive.
20 . The electrochemical energy storage device of claim 19 , wherein the plurality of active material particles are silicon particles.
21 . The electrochemical energy storage device of claim 19 , wherein the anode comprises one or more of graphite, hard-carbon, tin, and germanium particles mixed with the plurality of active material particles.
22 . The electrochemical energy storage device of claim 19 , wherein the at least one polymer comprises polyacrylonitrile (PAN).
23 . The electrochemical energy storage device of claim 19 , wherein the LiPF 6 and LiF SI lithium salts are present in the range of from 10 to 30 wt. % of the electrolyte and the fluoroethylene carbonate is present in the range of from 10 to 30 wt. % of the electrolyte.
24 . The electrochemical energy storage device of claim 19 , wherein the cathode comprises a lithium metal oxide, spinel, olivine, carbon-coated olivine, vanadium oxide, lithium peroxide, sulfur, polysulfide, a lithium carbon monofluoride or mixture thereof.
25 . The electrochemical energy storage device of claim 19 , wherein the cathode is a transition metal oxide material and comprises an over-lithiated oxide material.
26 . The electrochemical energy storage device of claim 19 , further comprising a porous separator separating the anode and cathode from each other.