3D Self-Supporting Carbon Nanotube–Porous Carbon–MnO 2 Sponges for Zinc-Ion Batteries

MnO 2 -based zinc-ion batteries (ZIBs) are an energy storage system characterized by high-safety, low cost, and high theoretical capacity. However, MnO 2 cathodes suffer from poor conductivity and structural instability, which are detrimental to their energy storage performance. Herein, we utilize a carbon nanotube-pitch-derived porous carbon (CNT-PPC) sponge as a self-supporting substrate for depositing MnO 2 . As a ZIB cathode, the CNT-PPC-MnO 2 sponge exhibits a high specific capacity of 411.7[Formula: see text]mAh/g at 0.1[Formula: see text]A/g, high rate capability, and stable cycling performance. The zinc-ion storage kinetics are investigated via electrochemical mechanism analysis and calculations. The as-prepared CNT-PPC-MnO 2 sponge//Zn ZIB can deliver a high-energy density of 556[Formula: see text]Wh/kg. This work provides a design strategy of a self-supporting carbon-based substrate for loading active materials.