Stabilizing Benzoquinone Cathodes via a Nanopore-Confined Dual-Site Mechanism for Aqueous Zinc Batteries.

Abstract

Benzoquinone (BQ) is considered a promising cathode material for aqueous zinc-ion batteries due to its simplest molecular structure and highest theoretical specific capacity among quinones. However, intrinsic problems derived from BQ including severe dissolution, narrow crystal interplanar <i>d</i>-spacings accessible by desolved Zn²⁺ only, and poor conductivity cause inferior battery performance. Herein, a strategy based on a "nanopore-confined dual-site synergy mechanism" is proposed to stabilize the BQ cathode and boost Zn²⁺ desolvation/coordination reactions for stable and fast Zn storage, which is realized by the construction of CoS₂ nanodot-embedded MOF-derived porous carbon (MPC) as an efficient host for BQ molecules. The MPC provides enough pore space to accommodate a substantial amount of BQ molecules with good electric conductivity, whereas CoS₂ in pores offering abundant Co and S sites exerts strong chemical binding over BQ species and facilitates Zn²⁺ desolvation/coordination, respectively, synergistically suppressing the dissolution of cathodes and imparting the rapid reaction kinetics of batteries. Consequently, the developed BQ@CoS₂-MPC cathode delivers a high reversible capacity of 458 mA h g^-1 at 0.5 C, excellent rate capability, and pronounced cycling stability with a low decay of 0.003% per cycle for over 10,000 cycles at 20 C. The work proposes an effective strategy toward high-performance organic electrode materials.