High-rate and long-life flexible aqueous rechargeable zinc-ion battery enabled by hierarchical core–shell heterostructures

Abstract

Aqueous rechargeable zinc-ion batteries (ZIBs) are potential alternative candidates for current commercial lithium-ion batteries due to their cost-efficiency, safety and sustainable nature. As one of the prominent cathode materials, MnO₂ exhibits high operating voltage and theoretical capacity. Yet, its poor electrochemical kinetics, low conductivity, and lifespan prevent its further application. Herein, an effective strategy for the construction of hierarchical TiN@MnO₂ nanowire arrays (NWAs) core–shell heterostructures directly grown on carbon cloth (CC) is demonstrated to systematically solve the above issues. First-principles calculations reveal that decreased bandgap and Zn²⁺ diffusion barrier as well as more stable structure of the host material after Zn²⁺ insertion promote the electrochemical kinetics of TiN@MnO₂. As a result, TiN@MnO₂ NWAs/CC exhibits significantly increased capacity (385.1 vs. 310 and 194 mA h g⁻¹ at 0.1 A g⁻¹), rate performance (127.6 mA h g⁻¹vs. 49.7 and 37.4 mA h g⁻¹ at 4.0 A g⁻¹) and cycling stability (101.6% capacity retention over 2300 cycles vs. 14.0% and 11.9%) compared with TiO₂@MnO₂ NWAs/CC and MnO₂ NSs/CC, respectively. Finally, the as-assembled flexible ZIBs with TiN@MnO₂ NWAs/CC cathode deliver an ultrahigh energy density of 327.7 W h kg⁻¹ at 135.6 W kg⁻¹. The proposition of the core–shell idea provides a novel strategy for development ZIBs.