Defective carbonized wood membrane as a free-standing three-dimensional anode host for high-performance Zn-ion batteries

Three-dimensional (3D) porous carbons as the host matrix of Zn anodes have been proven to be effective in suppressing Zn dendrite formation during the cycling of aqueous Zn-ion batteries (ZIBs), but the complex fabrication process and the lack of sufficient active sites for Zn nucleation still limit their practical applications. Herein, we developed a free-standing 3D carbon-based Zn anode (Zn/HDCW) by controllably electrochemically depositing Zn within a highly defective, hierarchically porous carbonized wood (HDCW) membrane obtained via the CO2 thermal etching of carbonized wood (CW). The HDCW features not only numerous open aligned microchannels and excellent wettability for fast electrolyte transport but also abundant carbon defects for effectively binding with Zn2+, enabling uniform plating and stripping of Zn and thus greatly suppressing the formation of Zn dendrites. As a result, the Zn/HDCW-based symmetric cell exhibits long-term cycling stability nearing 2700 h at 1 mA cm-2 with low voltage hysteresis. Furthermore, the Zn/HDCW anode offers the corresponding aqueous Zn/HDCW-MnO2/HDCW full cell with remarkable rate capability and cycling stability, delivering a stable capacity of 170.8 mAh g-1 at 1 A g-1 after 600 cycles with a unit coulombic efficiency and an excellent capacity retention of 100%. This work provides a new insight into the development of 3D porous carbon-based Zn anodes for high-performance ZIBs.