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

Abstract

With the continued rising demands for new advanced rechargeable batteries, 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 entrance of MIBs into large-scale applications due to the sluggish kinetics and irreversible insertion of Mg2+. Herein, the novel layered hewettite HKV6O16·4H2O/CNT (HKVO/CNT) nanosheets as robust cathode materials are designed for sustainable magnesium-ion storage. Compared with the bare HKVO, HKVO/CNT exhibits an appreciable specific capacity of 280 mA h g–1 at 20 mA g–1 and an outstanding capacity retention of about 90% after 4500 cycles. Furthermore, the systematic electrochemistry and structural testing determine that HKVO/CNT could be a promising high-performance cathode material for MIBs.