Biochar‐Derived Hierarchical Porous Carbon as Tellurium Host for High‐Performance Potassium‐Tellurium Batteries

Potassium‐ion battery is promising for its high abundance and low redox potential. As a conversion cathode, Te possesses high conductivity and theoretical volumetric capacity to couple with potassium. The stubborn issues of K‐Te battery focus on the large volume change and rapid structure degradation of Te. Herein, we produce biomass carbon from mangosteen shell in a facile method, and obtain a hierarchical porous host with abundance of micropores and mesopores, which is obviously beneficial for hosting Te during K+ storage in K‐Te battery. The specific capacity reach to 560 mAh g−1 in the initial cycle at 0.1 A g−1, and remained 83.8 % after 200 cycles. Impressively, at a high current density of 2.0 A g−1, the specific capacity still remained 62.6 % after 5000 cycle. These results endow such strategy an efficient way for the development of K‐Te batteries. The Te@PC‐MS composites based on the biomass carbon from mangosteen shell exhibit the superior K+‐storing performances. The existence of abundance of micro‐/mesopores in the hierarchical structure could effectively alleviates volume fluctuance during K‐Te battery operation.