L.S. Wu 1, Y.Y. Mei 1, Y.H. Liu, W. Xu, M.H. Zhang, Y.F. Dong *, Z.-S. Wu *

Chemical Engineering Journal, 2023, 459.

DOI: 10.1016/j.cej.2023.141662 [PDF]

Low-cost and nontoxicmanganesedioxide (MnO₂) cathodes have shown promising application in high-capacity and high-voltage rechargeable zinc ion batteries (ZIBs), but suffer from limited cycling life and energy density mainly due to poor electrical conductivity and structural failure induced by manganese dissolution and H⁺/Zn²⁺co-intercalation in traditional aqueous electrolytes. Herein, two-dimensional strongly-coupled δ-MnO₂/MXene heteronanosheets are efficiently developed for high-performance ZIBs, which mainly includes an in-situ polymerization of dopamine on Ti₃C₂MXene surface and subsequent redox reaction between KMnO₄and polydopamine. Benefited from the conductive MXene nanosheets for fast electron transfer, and the thin thickness of δ-MnO₂nanosheets for improved Zn²⁺insertion kinetics and structural stability, the δ-MnO₂/MXene heteronanosheets exhibit unique Zn²⁺-exclusive storage mechanism without proton storage induced disadvantages (e.g., Mn dissolution in traditional aqueous electrolytes) and superior zinc storage performance in 0.5 M zinc triflate in triethyl phosphate organic electrolyte(Zn(OTf)2/TEP), offering a capacity of ~163 mAh g⁻¹at 100 mA g⁻¹,a high capacity retention of 84.5% after 1000 cycles, and an areal capacity of 1.9 mAh cm⁻²when the mass loading is up to 10.5 mg cm⁻². This work providesunique Zn²⁺-exclusive storage mechanism of δ-MnO₂in organic electrolyte and opens up a new approach for building high-performance ZIBs.