P-modified carbon nanosheet with abundant through-hole channels for boosting Zn-ion storage under low-temperature

Abstract

Zinc-ion hybrid capacitors (ZIHCs) as a promising energy storage system suffer from unsatisfactory capability due to mismatched pore structure and lack of active sites in the carbon cathodes. Herein, a coupling strategy of oxidation template and in-situ doping is proposed to design a P-modified carbon nanosheet with abundant through-hole channels. Phosphorus doping not only reduces the electrode/electrolyte interface impedance, but also increases the available active sites. Through-hole channels enhance the Zn²⁺ accessibility. Therefore, the assembled ZIHCs provide an ultra-high energy density of 194.23 Wh kg⁻¹. Even at 0 °C, the ZIHCs retain a superior capacity of 166.0 mAh/g and stabilize for 10,000 cycles with capacity retention of 95.33 %. This work provides new insights into the design of carbon cathodes for boosting the Zn²⁺ storage.