Stable Manganese‐Oxide Composites as Cathodes for Zn‐Ion Batteries: Interface Activation from In Situ Layer Electrochemical Deposition under 2 V

Abstract

A set of multiphase manganese‐oxide composite materials (Mn2O3@Mn3O4 and Mn3O4@Mn5O8), and a birnessite‐type KxMnO2 oxide are prepared and evaluated as cathodes for Zn‐ion batteries. The species formed when the electrodes are subjected to 2 V in aqueous solutions of MnSO4 and ZnSO4 are analyzed, suggesting an interphase activation leading to enhancement of electrochemical response. For the first time, it is shown that a Zn4(SO4)(OH)6.xH2O phase coats the composite‐type electrodes in the charging stage, contributing to extending the lifetime of the batteries. KxMnO2 electrode with layered birnessite structure shows long cycling life at low current densities (122 mAh g−1 at 30 mA g−1 after 50 cycles) and good efficiencies (ca. 99%) in the 0.1 Mn2+ electrolyte. In contrast, in the 0.5 m Mn2+ electrolyte, high values of specific capacity are delivered by the cell at higher rates, that is, 150 mAh g−1 at 600 mA g−1. In Mn5O8@Mn3O4 the good performance is due to the synergistic effect of the two compounds forming the composite. Thus, after more than 100 cycles this composite displays specific capacity values of 175 mAh g−1 at 2150 mA g−1 in the 0.1 m Mn2+/1 m Zn2+ electrolyte.

Recent Advances on Challenges and Strategies of Manganese Dioxide Cathodes for Aqueous Zinc‐Ion Batteries

“…[57,58] Secondly, Mn 2+ ions are easy to dissolve continuously from the cathode materials into the electrolyte during the charging and discharging process. [59][60][61] In addition, the poor electrical conductivity of MnO 2 materials affects the conduction of electrons, which is not conducive to the insertion and extraction of Zn 2+ ions. [62,63] The common problems seriously lead to the rapid capacity decay, unsatisfactory cycling stability, and rate capability of AZIBs in the process of cycling.…”

Stable Imprinted Zincophilic Zn Anodes with High Capacity

“…Besides, the MnO 2 @C//Sn@Zn-IP can also exhibit a high energy density of 127.12 Wh kg -1 at a power density of 1290 W kg -1 , which is higher than those of previously reported ZIBs. [48][49][50][51][52][53]…”

Regeneration of spent lithium manganate into cation‐doped and oxygen‐deficient MnO2 cathodes toward ultralong lifespan and wide‐temperature‐tolerant aqueous Zn‐ion batteries

“…Electrodeposition is an inexpensive, simple, and binder‐free method for the preparation of manganese‐based materials. Owing to its high selectivity, high efficiency, low byproducts, and easily adjustable current and voltage for the synthesis process, it has been receiving more and more attention in recent years 31–33 . Moreover, because the material synthesized by this method has good adhesion to the collector fluid, there is no need to add adhesives and conductive agents to the collector fluid 34 .…”

“…Owing to its high selectivity, high efficiency, low byproducts, and easily adjustable current and voltage for the synthesis process, it has been receiving more and more attention in recent years. [31][32][33] Moreover, because the material synthesized by this method has good adhesion to the collector fluid, there is no need to add adhesives and conductive agents to the collector fluid. 34 The cations in solution during electrodeposition are able to be pre-embedded in the original MnO 2 lattice, which contributes to accelerate the ion/ electron dynamics, allowing to provide a stable material structure effectively.…”