ELECTROLYTE FORMULATIONS FOR ELECTROCHEMICAL CELLS CONTAINING A SILICON ELECTRODE
Additives to electrolytes that enable the formation of comparatively more robust SEI films on silicon anodes. The SEI films in these embodiments are seen to be more robust in part because the batteries containing these materials have higher coulombic efficiency and longer cycle life than comparable batteries without such additives.
1 . A method of forming a solid-electrolyte interphase on an anode in a lithium ion battery, comprising:
charging and discharging the lithium ion battery, wherein the lithium ion battery comprises: (i) an anode comprising silicon; (ii) a cathode; and (iii) an electrolyte solution; wherein the electrolyte solution comprises ethylene carbonate, an organic additive comprising a silicon-containing group, and a lithium salt.
2 . The method of claim 1 wherein the battery is charged to at least 4.2 V.
3 . The method of claim 1 wherein the battery is charged to greater than 4.2 V.
4 . The method of claim 1 wherein the battery is charged to at least 4.45 V.
5 . The method of claim 1 wherein the battery is charged and discharge at least 200 times and the solid-electrolyte interphase remains stable as demonstrated by a capacity retention by the battery of at least 60% at cycle 200.
6 . The method of claim 1 wherein the battery is charged and discharge at least 200 times and the solid-electrolyte interphase remains stable as demonstrated by a capacity retention by the battery of at least 70% at cycle 200.
7 . The method of claim 1 wherein the battery is charged and discharge at least 200 times and the solid-electrolyte interphase remains stable as demonstrated by a capacity retention by the battery of at least 80% at cycle 200.
8 . The method of claim 1 wherein the battery is charged and discharge at least 200 times and the solid-electrolyte interphase remains stable as demonstrated by a capacity retention by the battery of at least 90% at cycle 200.
9 . The method of claim 1 wherein the cathode comprises LiNi x Mn y Co z O w , where x+y+z=1 and 0<w<3.
10 . The method of claim 1 wherein the organic additive is selected from the group consisting of mono-(trimethylsilyl)phosphite, tris(trimethylsilyl)phosphite, tris(trimethylsilyl)phosphate, tris(trimethylsilyl)borate 99%, tris(trimethylsiloxy)vinylsilane, tris(trimethylsilyl)silane, or tris(trimethylsiloxy) ethylene.
11 . The method of claim 1 wherein the organic additive comprises mono-(trimethyl silyl)phosphite.
12 . The method of claim 1 wherein the organic additive comprises tris(trimethylsilyl)phosphite.
13 . The method of claim 1 wherein the organic additive comprises tris(trimethylsilyl)phosphate.
14 . The method of claim 1 wherein the organic additive comprises tris(trimethylsilyl)borate 99%.
15 . The method of claim 1 wherein the organic additive comprises tris(trimethylsiloxy)vinylsilane.
16 . The method of claim 1 wherein the organic additive comprises tris(trimethylsilyl)silane.
17 . The method of claim 1 wherein the organic additive comprises tris(trimethylsiloxy) ethylene.