High-Energy and Long-Lived Zn-MnO Battery Enabled by a Hydrophobic-Ion-Conducting Membrane.

Alkaline Zn-MnO batteries feature high security, low cost, and environmental friendliness while suffering from severe electrochemical irreversibility for both the Zn anode and MnO cathode. Although neutral electrolytes are supposed to improve the reversibility of the Zn anode, the MnO cathode indeed experiences a capacity degradation caused by the Jahn-Teller effect of the Mn ion, thus shortening the lifespan of the neutral Zn-MnO batteries. Theoretically, the MnO cathode undergoes a highly reversible two-electron redox reaction of the MnO/Mn couple in strongly acidic electrolytes. However, acidic electrolytes would inevitably accelerate the corrosion of the Zn anode, making long-lived acidic Zn-MnO batteries impossible. Herein, to overcome the challenges faced by Zn-MnO batteries, we propose a hybrid Zn-MnO battery (HZMB) by coupling the neutral Zn anode with the acidic MnO cathode, wherein the neutral anode and acidic cathode are separated by a proton-shuttle-shielding and hydrophobic-ion-conducting membrane. Benefiting from the optimized reaction conditions for both the MnO cathode and Zn anode as well as the well-designed membrane, the HZMB exhibits a high working voltage of 2.05 V and a long lifespan of 2275 h (2000 cycles), breaking through the limitations of Zn-MnO batteries in terms of voltage and cycle life.