Highly Reversible Aqueous Zn‐MnO₂ Battery by Supplementing Mn²⁺‐Mediated MnO₂ Deposition and Dissolution

Abstract

Rechargeable Zn‐MnO2 batteries are boosted by the reversible intercalation reactions in mild aqueous electrolytes, but they still suffer from cathode degradation. Herein, Zn‐MnO2 batteries with high durability and high energy density are achieved by supplementing MnO2 deposition and dissolution in a mild aqueous electrolyte. The main finding is that adjusting Mn2+ concentration to a critical range enables a reversible MnO2/Mn2+ redox conversion without the involvement of oxygen evolution. This can recycle the by‐products from MnOOH disproportionation (MnOOH → MnO2 + Mn2+), resulting in a battery with extremely high durability (16 000 cycles without obvious capacity fading), high energy density (602 Wh kg−1 based on the active mass of the cathode), and high‐rate capacity (430 mAh g−1 at 19.5 A g−1). The utilization of a 3D carbon nanotube foam skeleton can accommodate the volume change during MnO2 deposition/dissolution and provide paths for efficient charge and mass transport. This work provides a feasible way to push the development of Zn‐MnO2 batteries in mild aqueous electrolytes.

Construction of Bio‐inspired Film with Engineered Hydrophobicity to Boost Interfacial Reaction Kinetics of Aqueous Zinc–Ion Batteries

“…This phenomenon is ascribed to the faster reaction kinetics of the H + insertion/extraction process. [39,48,49] In comparison, the GCD curves of the MC sample are similar to the PMC-8 cathode, but the inflection point becomes indiscernible at a low current density of 0.2 A g -1 (Figure S8, Supporting Information). [44] Besides, when compared with other reported MnO 2 -based cathode materials, PMC-8 cathode also exhibits desirable energy and power densities, and Ragone plot is illustrated in Figure 5c.…”

Methods for Rational Design of Advanced Zn‐Based Batteries

“…Recently, Li et al constructed a new MnO 2 / MnOOH/Mn 2+ cyclic chemistry by regulating the concentration of Mn 2+ in aqueous ZnSO 4 /MnSO 4 electrolyte, effectively improving the energy density of the battery. [77] Yet, the incomplete dissolution of MnO 2 and the low intrinsic conductivity of the thick MnO 2 hindered the long-term stability, especially at high areal capacities. To address this challenge, Lu et al proposed a I -/I 3 reaction mediator to facilitate MnO 2 dissolution/ deposition.…”

The origin of capacity fluctuation and rescue of dead Mn-based Zn–ion batteries: a Mn-based competitive capacity evolution protocol

“…In order to address this issue, adding a certain amount of Mn 2+ ions into the electrolyte has been widely demonstrated as an effective approach to suppress the Jahn-Teller effect of manganese oxides. [22][23][24][25][26] Nonetheless, the side reactions introduced by Mn 2+ ion additives increase the complexity of aqueous ZIB chemistry. On the one hand, the Mn 2+ electrolyte additive may positively contribute to extra capacity.…”