Enhanced performance of Li-ion cell with LiBF4-PC based electrolyte by addition of small amount of LiBOB

LiBF4-PC based electrolytes have superior potentials in enhancing cycling performance of Li-ion cells at low temperature and at high current rate, respectively. However, their application is prevented because of the poor capability in enabling graphite to form a solid electrolyte interface (SEI). In this work, we found that addition of small amount of lithium bis(oxalate)borate (LiBOB) into the LiBF4-based electrolytes could significantly promote SEI formation on the surface of graphite even in solutions with a high content of PC. This is attributed to the fact that LiBOB participates in the formation chemistry of the SEI. Results showed that 1–5 mol% LiBOB is sufficient to promote graphite cycling reversibly in 1.0 m LiBF4 1:1:3 PC/EC/EMC and 1.0 m LiBF4 1:1 PC/EC, respectively, while the excellent cycling performance of LiBF4-PC based electrolytes at low temperatures was maintained.