Co₂V₂O₇@Ti₃C₂T_x MXene Hollow Structures Synergizing the Merits of Conversion and Intercalation for Efficient Lithium Ion Storage

Rechargeable batteries are deemed as green and efficient energy storage systems and have drawn great attention during past decades. Despite the commercial applications of lithium-ion batteries, the ever-increasing demands for higher energy storage capability driven by the rapid development of portable/wearable electronics remain unsatisfied due to the low theoretical capacity of the commonly used graphite anode. Herein, a material design strategy by synergizing the merits of conversion-type Co₂V₂O₇ and intercalation-based Ti₃C₂T_x MXene for efficient lithium-ion storage is reported. The Co₂V₂O₇@MXene hollow polyhedrons are synthesized by ion exchange, surface modification, and the subsequent electrostatic assembly. Benefiting from the high conductivity and mechanical robustness of the MXene sheath, the high theoretical capacity of Co₂V₂O₇, and the unique hollow structure, the optimized hybrids deliver a high output capacity of 949.7 mAh g⁻¹ at 0.1 A g⁻¹, excellent rate capacity with 431.4 mAh g⁻¹ retained at 5.0 A g⁻¹, as well as outstanding cycling stability.