Synergistically optimizing ion-electron transport processes through crystalline-amorphous phase and charge regulation for high-energy-density zinc-ion batteries

Abstract

Rapid ion-electron transport kinetics play a pivotal role in realizing high-efficiency aqueous zinc-ion batteries. However, the sluggish Zn 2+ intercalation kinetics in MnO 2 crystal lattices and the intrinsically low conductivity of MnO 2 have hindered the development of aqueous Zn-MnO 2 systems. As an effective modification method, doping has been widely acknowledged for modifying lattices and optimizing electronic structures. Herein, we synthesize a crystalline-amorphous P/C co-doped MnO 2 cathode (P/C-MnO 2 ) featuring high-valent P 5+ -O bonds via dual-ion co-doping. The charge compensation mechanism effectively reduces Mn valence states, facilitating ion diffusion and stabling phase structure. The crystalline phase part ensures an ordered electron transfer path and enhancing redox reaction reversibility, while the introduction of amorphous phase carbon helps improve conductivity. Concurrently, surface carbonyl functional groups and expanded interlayer spacing synergistically accelerate ion capture and transport. The Zn 2+ /H + co-intercalation storage mechanism is systematically elucidated through ex-situ characterizations. The optimized P/C-MnO 2 delivers an exceptional discharge capacity of 323.52 mA h·g −1 at 0.1 A·g −1 as well as maintains 80.9 % capacity retention over 700 cycles at 0.8 A·g −1 , achieving a high energy density of 410.24 W h·kg −1 . This work demonstrates that synergistic modulation of lattice architecture and charge configuration enables highly efficient electron-ion transport processes in advanced cathode materials. • Amorphous C doping enhances conductivity by promoting electron transport. • The formation of the P-O bond facilitates the transfer of ions and enhances electrochemical activity • P/C doping synergistically enhanced battery charge transfer and reaction activity.

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