Honeycomb-shaped microporous carbon-confined selenium as a Zn–Se battery cathode material

Selenium (Se) has emerged as a promising cathode material for zinc-ion batteries due to its high specific capacity, superior safety characteristics, and enhanced electrical conductivity compared with sulfur. However, the severe volume expansion of Se during cycling leads to structural degradation, significantly hindering its practical effectiveness. Herein, we propose a confinement strategy using microporous carbon matrices to mitigate volumetric expansion, thereby improving both rate capability and cycling stability. The optimized Se@C demonstrates exceptional electrochemical performance, delivering a high initial reversible capacity of 373.36 mAh g^-1 at 0.1 A g^-1 and appropriate cycling performance with a capacity of 90.23 mAh g^-1 after 500 cycles at 2 A g^-1. The low internal resistance and rapid ion/electron transport kinetics contributing to superior performance are further elucidated through <i>in situ</i> electrochemical impedance spectroscopy and distribution of relaxation time analyses.