In situ polymerized synthesis of MnO nanoparticles anchored on N,S co-doped carbon as efficient cathodes for quasi-solid-state zinc ion batteries

Abstract

Manganese-base cathodes have attracted enormous attention in rechargeable aqueous zinc ion batteries (AZIBs) owing to their high energy density and abundant reserves. However, the low electrical conductivity and the inevitable structural degeneration limit their rate performance and cycle life. Herein, MnO nanoparticle cathode materials confined in porous nitrogen, sulfur co-doped porous carbon (MnO@NSC) are prepared by employing acrylamide (AM) monomers as the chelating agents and C source. In the functionalized configurations, porous NSC can act as both a conductive layer and an interface protective layer, enabling MnO@NSC cathodes with remarkable electrochemical performances in terms of enhanced rate performance, long lifespan (∼94.3% capacity retention after 5000 cycles), and remarkable energy density (474.7 W h kg⁻¹), better than most reported MnO_x cathode materials. We further assemble a quasi-solid-state AZIB using a PAM hydrogel electrolyte with ZnSO₄ + MnSO₄. The device exhibits a low self-discharge rate (∼99.1% coulombic efficiency after being placed for 48 h), good environmental suitability, and impressive energy density (411 W h kg⁻¹), and is able to drive small electronics. This paradigm work puts forward a facile, time-saving, efficient and eco-friendly strategy to fabricate sustainable MnO@NSC cathode materials for ZIBs, which also offer great opportunities for engineering other nanoparticle@NSC hybrids for energy conversion and storage.