Dual Strategy of Morphology Optimization and Interlayer Expansion in Vs2 Cathode Toward High-Performance Mg-Li Hybrid Ion Batteries

Combining the merits of dendrite-free formation of Mg anode and fast kinetics of Li-ions, the Mg-Li hybrid ion (MLIBs) batteries are considered as an ideal energy storage system. However, the lack of advanced cathode materials limits their further practical application. Herein, a dual strategy of morphology optimization and interlayer expansion is designed to fabricate the hierarchical flower-like VS2 architecture coated by N-doped carbon layers (denoted as E-VS2@C-200). The unique structure and N-doped carbon are beneficial for accommodating more active sites and enhancing the structural stability. Moreover, the enlarged interlayer spacing can effectively promote the charge transfer kinetics and facilitate the ion transport rate, as further demonstrated by electrochemical results and theoretical calculations. Benefiting from the above merits, the E-VS2@C-200 cathode exhibits superior specific energy density (644.4 Wh kg-1, average voltage of 1.2 V vs Mg2+/Mg) and excellent rate capability (181.1 mAh g-1 at 2000 mA g-1). A variety of ex-situ characterization methods are performed to investigate the ion storage mechanism, which confirms that Li+ storage plays a leading role in the capacity contribution of MLIBs. Our novel strategy is in favor of providing useful insights to design and construct MLIBs with high energy density and excellent rate performance.