A synergistic vertical graphene skeleton and S–C shell to construct high-performance TiNb2O7-based core/shell arrays

Abstract

Bespoke synthesis of wide-temperature high-power electrodes is of great importance for the development of advanced power-type lithium ion batteries (LIBs). Herein, we report a powerful combined solvothermal-electrodeposition (ST-ED) method to construct titanium niobium oxide (TiNb₂O₇) arrays sandwiched between a highly conductive vertical graphene (VG) skeleton and S–C shell forming a binder-free VG/TiNb₂O₇@S–C electrode. VG and S–C work cooperatively to establish an omnibearing conductive network on TiNb₂O₇ through internal and external integration. Positive advantages including large porosity, improved conductivity and enhanced structural stability are obtained in the VG/TiNb₂O₇@S–C core/shell arrays. Consequently, excellent electrochemical high-power performance at medium–high temperature (25 to 70 °C) is demonstrated for the designed VG/TiNb₂O₇@S–C electrodes, which show a high capacity from 284 to 354 mA h g⁻¹ at 1C, and 181 to 241 mA h g⁻¹ at 160C as the working temperature increases from 25 to 70 °C. Additionally, a remarkable high-temperature (70 °C) cycling span is proven for the VG/TiNb₂O₇@S–C electrode with a capacity of 203 mA h g⁻¹ at 40C after 5000 cycles. The synergistic positive effect from the VG and S–C shell is responsible for the enhancement of high-power capability. Our work paves the way for the fabrication of novel high-power electrodes for electrochemical energy storage.