Atomic engineering promoted electrooxidation kinetics of manganese-based cathode for stable aqueous zinc-ion batteries

Abstract

Rechargeable zinc-based batteries with near-neutral media are standing in the middle of the energy storage field by virtue of their high safety and low cost. However, it is still imperative for Mn-based cathode to improve rate capacity by facilitating ions/electron transfer and long-cycle stability by suppressing Mn dissolution. Herein, promoting electrooxidation kinetics is proposed and employed to construct advanced Mn−Zn battery. The formation of carbon-protected birnessite-MnO2 is promoted via inducing the electron-donating capability of the heterointerface between the N−C coating and the defective MnO. Moreover, density functional theory calculations also demonstrate that N−C protected birnessite-MnO2 is more hydrophobic than pure birnessite-MnO2, which is beneficial to prohibiting Mn dissolution and other side reactions. As a result, the elaborate design realizes effective transformation from low valence to high valence Mn for high capacity (291 mA·h·g−1) and protective bamboos-like structure for rate capacity (126 mAh·g−1 at 5 A·g−1) and cycling stability (89% capacity retention after 2,000 cycles). The assembled flexible quasi-solid-state Mn−Zn pouch batteries display application prospects for wearable and implantable electronic devices. The atomic engineering promoting electrooxidation kinetics strategy will be instructive in activating other cathode materials and maximizing their capacity.