Phase transformation mechanism of MnCO3 as cathode materials for aqueous zinc-ion batteries

Abstract

Aqueous rechargeable zinc-ion batteries (ZIBs) have been given more and more attention because of their high specific capacity, high safety, and low cost. The reasonable design of Mn-based cathode materials is an effective way to improve the performance of ZIBs. Herein, a square block MnCO3 electrode material is synthesized on the surface of carbon cloth by a one-step hydrothermal method. The phase transition of MnCO3 was accompanied by the continuous increase of specific capacity, and finally maintained good cycle stability in the charge–discharge process. The maximum specific capacity of MnCO3 electrode material can reach 83.62 mAh g−1 at 1 A g−1. The retention rate of the capacity can reach 85.24% after 1,500 cycles compared with the stable capacity (the capacity is 61.44 mAh g−1 under the 270th cycle). Ex situ characterization indicates that the initial MnCO3 gradually transformed into MnO2 accompanied by the embedding and stripping of H+ and Zn2+ in charge and discharge. When MnCO3 is no longer transformed into MnO2, the cycle tends to be stable. The phase transformation of MnCO3 could provide a new research idea for improving the performance of electrode materials for energy devices.

Crystalline MnCO3@Amorphous MnOx Composite as Cathode Material for High-Performance Aqueous Zinc-Ion Batteries

“…Based on the above analysis and related literature reports, ,, it can be concluded that during the first discharge process, H + is intercalated into the MnCO 3 @A-MnO x to form hydroxymanganese oxide first, and it is reasonable to report in the literature that although H + is intercalated in the intercalation layer, the characteristic peaks of hydroxymanganese oxide can hardly be observed, , and the subsequent reactions occur as a result of an increase in OH – in the system. It is worth mentioning that for the MnCO 3 electrode, there is no capacity at the first discharge, followed by a long plateau in its charging curve at the first charge process, as shown in Figure S10.…”

“…Therefore, the structure of the cathode material will undergo drastic changes, resulting in a sharp decline in the stability of the cathode material. , In order to overcome these deficiencies, MnO x with an amorphous state has been proposed and employed by researchers, which not only has the advantages of general MnO x but also has abundant structural defects that act as active sites for Zn 2+ storage. Moreover, amorphous MnO x itself is anisotropic, which can alleviate the volumetric strains during cycling, thus slowing down the structural collapse of the MnO x electrode. , In addition, it is worth noting that MnCO 3 , which is composed of MnO 6 octahedrons and carbonate and has a crystal structure very similar to that of MnO 2 , has recently received wide attention as a cathode material for AZIBs . The presence of low-valent Mn in MnCO 3 and the unique channel structure for easy Zn 2+ diffusion make it a potential cathode material for AZIBs However, the conductivity of MnCO 3 is very low, and to enhance its conductivity and thereby improve its electrochemical performance, modification strategies such as the use of conductive additives, defect engineering, and structure optimization design are introduced. − …”

“Dual‐ Engineering” Strategy to Regulate NH4V4O10 as Cathodes for High‐Performance Aqueous Zinc Ion Batteries

“…Aqueous zinc ion batteries (AZIBs) have drawn significant attention from researchers due to their high theoretical capacity (820 mAh g −1 ), low redox potential (−0.76 V vs SHE), abundant resources, and environmental friendliness. [12,13] However, it is still early for the wide application of zinc ion batteries in water system. One of the main reasons that hinder its application is the lack of right cathode materials.…”

Phase-Transformation-Activated MnCO3 as Cathode Material of Aqueous Zinc-Ion Batteries

“…Manganese carbonate (MnCO 3 ) possesses a similar crystal structure to MnO 2 [28], reveling its potential as an electrode material. It has been widely investigated in the field of supercapacitors [29,30], which can realize a high voltage platform in alkaline electrolytes [31].…”

“…By contrast, MnCO 3 has many advantages, such as rich reserves, environmental friendliness, and easy synthesis. Moreover, its chemical properties are so active and stable that the charge transfer occurs in the process of phase transition, which provides a better cycle stability [28]. MnCO 3 is also widely used as an anode for LIBs [32].…”