Excellent Rate Performance and Cycling Stability of TiP₂O₇@C/Carbon Nanotubes for the Aqueous Rechargeable Lithium-Ion Battery

A novel anode composite, carbon-coated TiP₂O₇ nanoparticles (TPO@C) decorated with carbon nanotubes (CNTs), is fabricated through a simple sol–gel method and a calcination process for aqueous rechargeable lithium-ion batteries (ARLBs). The complete interfacial contact of TPO@C and CNTs provides a 3D network structure with a high specific surface area. The effects of CNTs on the diffusion coefficient of lithium ions, rate performance, and cycle performance are investigated. Typically, the discharge capacities of the TPO@C/CNTs anode can reach up to 97.88, 93.86, 90.79, 86.54, and 77.42 mA h g⁻¹ at the current densities of 0.2, 0.5, 1, 2, and 5 A g⁻¹, respectively. At an extremely high current density of 10 A g⁻¹, the discharge capacity over 800 cycles is almost as high as the initial discharge capacity. Moreover, a (TPO@C/CNTs)//LiMn₂O₄ full cell in saturated LiNO₃ electrolyte is tested in a pouch cell. It also demonstrates a high reversible capacity of 83.51 mA h g⁻¹ (≈60.42% capacity retention) after 1000 cycles at 2 A g⁻¹. The results indicate that CNTs can promote the diffusion coefficient of lithium ions, and are responsible for the high rate performance and cycling stability.