Rational design of 1D nanowires with internal void space assembled by MnO@C nanoreactors as efficient cathodes for flexible zinc ion batteries

Abstract

MnO-based materials are one of the most promising cathodes for rechargeable zinc ion batteries (ZIBs) owing to their high energy density and abundant resources. However, the notorious electronic conductivity and large volumetric expansion issues have severely restricted their practical application. Herein, 1D nanowires (NWs) with abundant internal void space, composed of ultra-small MnO@C nanoreactors, is proposed to get rid of the above dilemma. Specifically, carbon layer dramatically enhances electrically conductive, the elaborated constructed void space between MnO@C nanoreactors effectively avoid the physical clogging and restacking of MnO, relieving the strain upon charge and discharge process, and ultimately ensuring cathode satisfactory integrity maintenance, different from traditional 1D NWs composite architecture. As expected, the NWs constructed by MnO@C nanoreactors exhibit the superior cycling stability (102.9% capacity retention after 2000 cycles) and good rate performance. Moreover, we firstly construct freestanding MnO@C NWs/CNTs film as cathode and assemble a quasi-solid-state ZIB by using soaking-free PAM hydrogel electrolyte. The device without extra binders and additives affords an impressive reversible capacity of 357.2 mAh g−1 at 0.1 A g−1, and remarkable volumetric energy density of 20.8 mWh cm−3 (higher than commercial Li thin-film battery). Furthermore, our soft-packaged ZIBs also exhibits satisfactory flexibility and high safety.