Ineffectiveness of Electrolyte Additives for Overcharge Protection in Li-Ion Battery

A series of well-known overcharge protecting electrolyte additives for Li-ion batteries (diphenyl ether (PE), biphenyl (BP), cyclohexyl benzene (CHB) and N, N-dimethylacetamide (DMAC) were tested at equal conditions. A high energy density prismatic cell with LiCoO2 as a cathode was used. Overcharge additives in various concentrations in electrolyte (EC/PC/EMC, 1.1M LiPF6) were overcharged at 1C/12V conditions. The additives' influences on electrochemical cell performance were tested as well. None of the tested additives showed any notable improvements on battery safety during overcharge. Possible mechanisms of Li ion battery failure at overcharge will be discussed.