Use of chloroethylene carbonate as on electrolyte solvent for a graphite anode in a lithium-ion battery

The electrolyte decomposition during the first lithiation of graphite is reduced to 90 mAh/g in an electrolyte containing equal volumes of chloroethylene carbonate and a cosolvent of propylene carbonate, dimethyl carbonate, or diethyl carbonate. The Volume fraction of chloroethylene carbonate can be further reduced to 0.05 in a trisolvent system with a cosolvent containing equal volumes of ethylene carbonate and propylene carbonate. A lithium-ion cell containing chloroethylene carbonate and propylene carbonate shows a long cycle life. The capacity decreases by 20% from the initial value in over 800 cycles. The charging efficiency is 80 to 90%, is rate dependent, and is accompanied by a self-discharge mechanism. A hypothesis of a chemical shuttle is suggested to explain the low charge efficiency and self-discharge.