Ultrahigh reversible lithium storage of hierarchical porous Co–Mo oxides via graphene encapsulation and hydrothermal S-doping

Abstract

The construction of a complex structure and component adjustment are effective strategies for improving volume expansion and conductivity of transition metal oxides, which serve as promising anode materials in lithium-ion batteries with high capacity. Herein, a facile metal–organic framework-engaged strategy was demonstrated for the synthesis of hierarchical porous CoMoO₄–CoO/S@rGO nano polyhedrons via hydrothermal S doping. The improvement of S doping originated from enlarged interplanar spacing, enhanced conductivity, and increased pseudocapacitance contribution. Meanwhile, the porous structure relieved volume expansion during the lithiation/delithiation processes and exposed more active sites of Li storage. The CoMoO₄–CoO/S@rGO electrode exhibited ultrahigh specific capacity (1103 mA h g⁻¹ at 0.5 A g⁻¹) and excellent rate capacity (652 mA h g⁻¹ at 5 A g⁻¹). This work indicated that the rational structural design and insights into anionic doping have guiding significance for other metal oxides with high capacity and high-rate capability.