GEL ELECTROLYTE FOR AN ELECTROCHEMICAL CELL
Processes of improving the safety of lithium ion cells are provided without compromising cell performance. Provided are processes of forming a gel electrolyte that for the first time can fully substitute a liquid electrolyte and provide similar performance but also has greatly improved safety. A process includes in situ formation of a gel electrolyte in the presence of a liquid electrolyte material and then subjecting the resulting gel to a wetting step. The resulting gel electrolyte is capable of excellent cycle life and capacity without the presence of remaining liquid electrolyte.
1 . A process for formation of an electrochemical cell comprising:
providing a substrate;
contacting said substrate with a precursor material, said precursor material comprising a monomer, oligomer, initiator, or combinations thereof, and a first electrolyte material comprising one or more lithium salts;
polymerizing for a polymerization time said precursor material to form a gel in contact with said substrate; and
contacting a second liquid electrolyte material with said gel and said substrate for a wetting time.
2 . The process of claim 1 further comprising removing excess liquid electrolyte material from said gel following said contacting step.
3 . The process of claim 1 or 2 wherein said step of polymerizing comprises thermal curing or ultraviolet curing.
4 . The process of claim 1 or 2 where said wetting time is from one to seventy-two hours.
5 . The process of claim 1 or 2 wherein said substrate is an electrode; said electrode is a cathode comprising a lithium metal oxide, a lithium metal phosphate, or combinations thereof; or said electrode is an anode comprising a graphite or graphite containing material, a silicon or silicon containing material, a transition metal oxide, or combinations thereof.
6 . The process of claim 1 or 2 wherein said precursor material further comprises a flame retardant additive.
7 . The process of claim 1 or 2 wherein said precursor material further comprises a current collector protection agent, a protection agent, or combinations thereof.
8 . The process of claim 1 or 2 wherein said initiator is an azo-compound, or a peroxide.
9 . The process of claim 1 or 2 wherein said substrate is an electrode, a separator, or more than one substrate is present where a first substrate is an electrode and where a second substrate is a separator.
10 . The process of claim 1 or 2 further comprising contacting said precursor material with a separator prior to said step of polymerizing.
11 . The process of claim 1 or 2 further comprising incorporating said substrate and said gel into an electrochemical cell absent additional electrolyte material.
12 . The process of claim 1 wherein said first electrolyte material and said second electrolyte material comprise the same electrolyte material.