Ultrathin cobalt nickel selenides (CoNiSe) nanosheet arrays anchoring on TiC MXene for high-performance Na/K batteries.

Sodium-ion batteries (SIBs) have received increasing interest for large-scale energy storage based on the high natural abundance and low-cost of sodium resources. However, owing to the large ionic radius of sodium ion, SIBs anodes exhibit sluggish charge kinetic and rapid capacity decay, which severely hindered their practical application. In this work, we develop a novel approach to couple two-dimensional (2D) bimetal Co-Ni selenide nanosheets with TiC MXene (TiC/CoNiSe) as anode material for SIBs. Specifically, the 2D bimetal nanosheets anchoring on MXene substrate can provide high specific capacity and alleviate volume expansion. Furthermore, the MXene substrate can shorten the diffusion pathway of sodium-ion and enhance electronic conductivity. The TiC/CoNiSe delivers a superior rate performance of 337 mAh g at 3000 mA g and excellent stability of 338 mAh g at 1000 mA g after 600 cycles. The presented strategy from combination of MXene and 2D bimetallic selenide may pave a way for the design and synthesis of high-performance SIBs anode materials.