Lithium dendrite-free and fast-charging for high voltage nickel-rich lithium metal batteries enabled by bifunctional sulfone-containing electrolyte additives

Abstract

Lithium dendrites limit the application of lithium metal as anode, and poor interfacial stability restricts the nickel-rich lithium nickel cobalt manganese oxides as cathode. Herein, diphenyl sulfone (DPS) and bis(4-florophenyl) sulfone (BFS) are proposed as bifunctional electrolyte additives. In the Li||Li symmetrical half-batteries, with 0.5 wt % DPS, high cycle stability for 360 h at the current density of 1 mA cm−2 is realized by forming a dense and smooth LiF-rich solid electrolyte interphase (SEI). In the Li||LiNi0.8Mn0.1Co0.1O2 (NMC811) battery, from the long-term cycle tests at 5C after 500 cycles, the capacity retention loss of 0.05% per cycle is found by addition of 0.5 wt% DPS, which is much lower than that with 0.5 wt% of BFS (0.08%) and no additives (0.16%). Proper content of LiF, Li2SO3 and ROSO2Li caused by DPS are beneficial to form a stable solid electrolyte interphase film for the Li||NMC batteries, which facilitates lithium ion transport, and inhibits electron transfer. Therefore, Li||NMC batteries with additives exhibit longer cycle life, higher capacity retention and better fast charging performance than that without any additive.