A one-for-all strategy of polyimide coating layer for resolving the comprehensive issues of phosphorus anode

Phosphorus is a promising anode with high capacity (2596 mAh g−1 and 6075 ∼ 6924 mAh cm−3), low lithium-ion diffusion barrier (0.08 eV), and appropriate lithiation potential (∼0.7 V vs Li+/Li). However, it faces the problems of huge volume expansion (∼300%), low electronic conductivity (10-14 ∼ 102 S cm−1), soluble intermediates (lithium polyphosphides, LixPs), degradation in air, and low thermal stability. In this work, phosphorus/carbon nanotube composites were coated with a polyimide layer, which plays the roles of a buffer layer to relieve the volume expansion of phosphorus, an obstruct layer to confine LixPs, an inert layer to prevent the degradation of phosphorus in air, a heat resistant layer to improve the thermal stability of the anode. The resulting composites (P/[email protected]) display high capacity retention of 798.1 mAh g−1 after 150 cycles at 1 A g−1, achieving 17 times as much as the control sample (P/CNT).