Robust Hewettite HKV6O16·4H2O/CNT Nanosheets As High-Performance Cathodes for Sustainable Mg2+ Storage

With the continued rising demands for new advanced rechargeablebatteries, the environment-friendly, low-cost, magnesium-ion batteries(MIBs) with high volumetric capacity emerge as the times require.However, some bottlenecks in the research of cathodes limit the entranceof MIBs into large-scale applications due to the sluggish kineticsand irreversible insertion of Mg2+. Herein, the novel layeredhewettite HKV6O16 center dot 4H(2)O/CNT (HKVO/CNT)nanosheets as robust cathode materials are designed for sustainablemagnesium-ion storage. Compared with the bare HKVO, HKVO/CNT exhibitsan appreciable specific capacity of 280 mA h g(-1) at 20 mA g(-1) and an outstanding capacity retentionof about 90% after 4500 cycles. Furthermore, the systematic electrochemistryand structural testing determine that HKVO/CNT could be a promisinghigh-performance cathode material for MIBs.