Cauliflower-like manganese oxide@carbon cathode with structural and interfacial dual optimization for ultrastable zinc-ion batteries.

Abstract

Manganese-based oxide cathode materials have attracted significant attention in aqueous zinc-ion batteries (AZIBs) due to their high energy density and operating voltage, but their practical applications are limited by the structural instability caused by manganese dissolution and sluggish kinetics resulting from poor electrical conductivity. Herein, a cauliflower-like MnO/carbon composite (NMOC) with hierarchical porous architecture is designed and fabricated through NaCl phase-dynamic regulation strategy by using a cost-effective manganese tartrate as the precursor. The dynamic NaCl template not only directs the self-assembly of MnO nanoparticles into three-dimensional interconnected porous frameworks but also facilitates the in-situ formation of an ultrathin (∼2 nm) carbon coating layer. As a high-performance cathode material for AZIBs, this unique structural configuration of NMOC establishes abundant Zn²⁺/H⁺ diffusion pathways, exposes high-density active sites, and significantly enhances reaction kinetics. Meanwhile, the strengthened Mn-O-C interfacial coupling and carbon confinement effect collectively suppress Mn dissolution, mitigate volume variation, and promote charge transfer dynamics. As a result, the NMOC cathode delivers an exceptional capacity of 561 mAh g^-1 at 0.2 A g^-1 and demonstrates ultra-stable cycling performance with 190 mAh g^-1 retained after 2000 cycles at 2 A g^-1 and nearly 100 % capacity retention (127 mAh g^-1) after 2500 cycles at 4 A g^-1. Furthermore, the constructed flexible cells demonstrated excellent mechanical and electrochemical properties. This work offers new insights into the interfacial modulation and kinetic optimization of manganese-based oxides in next-generation energy storage systems.