Multifunctional Hollow Core–Shell Carbon Nanosphere With High Catalytic Activity and Zinc Deposition Regulation Ability for Zinc‐Bromine Flow Battery

Abstract The high energy density and low cost enable the zinc‐bromine flow battery (ZBFB) with great promise for stationary energy storage. However, the sluggish reaction kinetics of Br 2 /Br − redox couple, uncontrollable bromine diffusion, and tricky zinc dendrites pose great challenges in their wider application. Herein, the multifunctional hollow core‐shell carbon nanospheres (HCSC) are designed as electrodes for ZBFBs, which are composed of carbon cores and hollow carbon shells. The abundant multistage pore structure, high specific surface area, and excellent bromine adsorption capacity of HCSC significantly improve the catalytic activity of the electrode. Meanwhile, bromine can be firmly confined in the cavity based on the adsorption effect, effectively inhibiting bromine diffusion and battery self‐discharge. Moreover, this unique core‐shell structure provides more deposition space, achieving uniform zinc deposition, further reducing the polarization and extending the lifespan of ZBFBs. The HCSC‐modified carbon felt (HCSC‐CF) thus achieves high catalytic activity, high bromine immobilization capacity, and excellent zinc deposition regulation ability simultaneously. Therefore, the assembled ZBFB achieves a high voltage efficiency of 71.29%, a high energy efficiency of 70.63%, and a long lifespan of over 340 cycles at a high current density of 160 mA cm −2 , showing great potential for further application.