High-Energy and Long-Lived Zn–MnO₂ Battery Enabled by a Hydrophobic-Ion-Conducting Membrane

Abstract

Alkaline Zn–MnO2 batteries feature high security, low cost, and environmental friendliness while suffering from severe electrochemical irreversibility for both the Zn anode and MnO2 cathode. Although neutral electrolytes are supposed to improve the reversibility of the Zn anode, the MnO2 cathode indeed experiences a capacity degradation caused by the Jahn–Teller effect of the Mn3+ ion, thus shortening the lifespan of the neutral Zn–MnO2 batteries. Theoretically, the MnO2 cathode undergoes a highly reversible two-electron redox reaction of the MnO2/Mn2+ couple in strongly acidic electrolytes. However, acidic electrolytes would inevitably accelerate the corrosion of the Zn anode, making long-lived acidic Zn–MnO2 batteries impossible. Herein, to overcome the challenges faced by Zn–MnO2 batteries, we propose a hybrid Zn–MnO2 battery (HZMB) by coupling the neutral Zn anode with the acidic MnO2 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 MnO2 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–MnO2 batteries in terms of voltage and cycle life.

Recent Advances in Aqueous Zn||MnO2 Batteries

“…In addition to electrolyte innovations, exploiting new cell configurations is another important development direction for commercializing aqueous Zn||MnO 2 batteries. Cui et al [46,47] designed a proton-shuttle-shielding and hydrophobic-ion-conducting membrane to separate the neutral anode and acidic cathode, . Adopted with permission from Ref.…”

Post-Lithium Batteries with Zinc for the Energy Transition

“…Furthermore, there is also the approach of decoupling the electrolyte ranges, so that the optimum pH value can be selected in each case regarding performance [113]. In this case, however, the different areas must be separated by suitable measures, such as jellification [57,[113][114][115] or through special membranes [58,116,117], since otherwise they would mix due to diffusion processes. Shen et al, for example, use hydrogel electrolyte in which three layers with different pH values are applied on top of each other [115].…”

Aqueous MnO2/Mn2+ electrochemistry in batteries: progress, challenges, and perspectives

“…13 However, the severe irreversibility of both Zn anodes (induced by passivation, corrosion, or dendrites problems) and MnO 2 cathodes (originating from the gradual dissolution issue or undecomposable discharge products) results in a poor cycling performance that makes alkaline Zn-MnO 2 batteries difficult to achieve adequate rechargeability. 14,15 Later, the reversibility of the Zn-MnO 2 battery has been effectively improved in the near-neutral system, which has greatly propelled the development of the rechargeable Zn-MnO 2 batteries and other MnO 2 -based batteries. 16 However, the in-depth investigations disclose the complexity of the reaction mechanism at the MnO 2 cathode that results in challenges to contrive both fundamental and applicational developments on MnO 2 -based batteries.…”