A novel flame‐retardant electrolyte additive for safer lithium‐ion batteries

Lithium-ion batteries (LIBs) have attracted much attention in the field of new energy. However, due to the flammability of its electrolyte, the batteries may have fire or even explosion accidents in unconventional environment. We have synthesized a new electrolyte additive, 1-diphenylphosphoryloxy-4-methylbenzene (DPMB), in the hope of improving the safety performance of LIBs by combining flame-retardant and overcharge protection. According to the results of the self-extinguishing time test and the differential scanning calorimetry test, it can see that the addition of DPMB can improve the flame retardancy of original electrolytes. Unfortunately, the electrochemical test results show that the oxidation potential of DPMB is 3.8 V, which indicate that DPMB cannot achieve the role of overcharge protection. But it is interesting that the addition of DPMB not only has no side effects on the LIBs performance, but also improves the cycle performance and rate capability of the LIBs to a certain extent, especially when the DPMB content is 2wt%. Our results provide a new choice of additives for improving the safety of LIBs electrolyte.