Elastic Anode Binder For Secondary Lithium Ion Battery
An electrochemical cell is prepared from a silicon-based anode active material and a polyimide-based binder prepared by curing polyamic acid with heat and/or with a catalyst. The silicon-based material may be silicon suboxide. Anodes prepared with combinations of an elastic polyimide-based binder and anode active material improve specific capacity, cycle characteristics, and electrical properties in secondary lithium batteries.
1 . An anode comprising a silicon-based anode active material and an elastic polyimide (PI)-based binder.
2 . The anode of claim 1 , wherein the silicon-based anode active material is selected from the group consisting of silicon suboxide, silicon carbonate, and silicon alloy.
3 . The anode of claim 1 , wherein the silicon-based anode active material is silicon suboxide.
4 . The anode of claim 1 , wherein the elastic PI-based binder has a degree of imidization between 15% and 100%.
5 . The anode of claim 1 , wherein the elastic PI-based binder has a degree of imidization between 15% and 50%.
6 . The anode of claim 1 , wherein the elastic PI-based binder has the structure:
7 . A method of preparing an anode comprising:
preparing an elastic PI-based binder by curing polyamic acid with heat and/or with a catalyst; and
combining the elastic PI-based binder with a silicon-based anode active material.
8 . The method of claim 7 , further comprising preparing the polyamic acid by mixing a diamine monomer and a tetracarboxylic dianhydride monomer.
9 . The method of claim 8 , wherein the diamine monomer is phenylenediamine.
10 . The method of claim 8 , wherein the tetracarboxylic dianhydride monomer is biphenyl-tetracarboxylic acid dianhydride.
11 . The method of claim 7 , wherein the silicon-based anode active material is selected from the group consisting of silicon suboxide, silicon carbonate, and silicon alloy.
12 . The method of claim 7 , wherein the silicon-based anode active material is silicon suboxide.
13 . The method of claim 7 , wherein the polyamic acid is cured at a temperature of 250 to 450 degrees Celsius to form the elastic PI-based binder.
14 . The method of claim 7 , wherein the polyamic acid is cured with a catalyst.
15 . The method of claim 14 , wherein the catalyst comprises N,N′-dimethylethanolamine.
16 . The method of claim 7 , wherein the polyamic acid is soluble in water and in N-methyl pyrrolidone.
17 . The method of claim 7 , wherein the polyamic acid has an imidization ratio of from about 50% to about 90% at a curing temperature of 150 degrees Celsius or less.
18 . A lithium secondary battery comprising a case, a positive terminal, a cathode, a separator, an electrolyte, a negative terminal and an anode, wherein the anode comprises a silicon-based anode active material and an elastic polyimide (PI)-based binder.
19 . The lithium secondary battery of claim 18 , wherein the silicon-based anode active material is selected from the group consisting of silicon suboxide, silicon carbonate, and silicon alloy.
20 . The lithium secondary battery of claim 18 , wherein the elastic PI-based binder has a degree of imidization between 15% and 50%.