Tailored imidazolium tetraphenylborate salts for the design of boron, nitrogen co-doped carbon materials as high-performance anodes for fast-rate monovalent ion batteries

Abstract

We report the synthesis of original imidazolium salts with the tetraphenylborate anion and their use as precursors for boron, nitrogen co-doped carbon materials. In addition to the beneficial effect of the tetraphenylborate anion, we showed that the presence of two benzyl groups on the imidazolium cation increases the carbonization yield (15 wt%), promotes the heteroatom-doping (16 wt% of nitrogen and 9 wt% of boron), improves the microstructure order and protects boron atoms from oxidation. The B, N co-doped carbon prepared from 1,3-bis(benzyl)imidazolium tetraphenylborate demonstrated fast-rate capabilities as an anode material for high-power monovalent ion batteries. After 1400 cycles at a high rate (30C) versus Li⁺/Li, 80% of the capacity was maintained (112 mA h g⁻¹).