An In Situ Interface Reinforcement Strategy Achieving Long Cycle Performance of Dual-Ion Batteries

Dual-ion batteries (DIBs) with high operation voltage offer promising candidates for low-cost clean energy chemistries. However, there still exist tough issues, including structural collapse of the graphite cathode due to solvent co-intercalation and electrolyte decomposition on the electrode/electrolyte interface, which results in unsatisfactory cyclability and fast battery failure. Herein, Li4Ti5O12 (LTO) modified mesocarbon microbeads (MCMBs) are proposed as a cathode material. The LTO layer functions as a skeleton and offers electrocatalytic active sites for in situ generation of a favorable and compatible cathode electrolyte interface (CEI) layer. The synergetic LTO-CEI network can change the thermodynamic behavior of the PF6-intercalation process and maintain the structural integrity of the graphite cathode, as a Great Wall to protect the cathode from structural collapse and electrolyte decomposition. Such LTO-CEI reinforced cathode exhibits a prolonged cyclability with 85.1% capacity retention after 2000 cycles even at cut-off potential of 5.4 V versus Li+/Li. Moreover, the LTO-modified MCMB (+)//prelithiated MCMB (-) full cell exhibits a high energy density of similar to 200 Wh kg(-1), remarkably enhanced cyclability with 93.5% capacity retention after 1000 cycles. Undoubtedly, this work offers in-depth insight into interface chemistry, which can arouse new originality to boost the development of DIBs.