Manganese Dioxide As Rechargeable Magnesium Battery Cathode

Abstract

Rechargeable magnesium battery (rMB) has received increased attention as a promising alternative to current Li-ion technology. However, the lack of appropriate cathode that provides high-energy density and good sustainability greatly hinders the development of practical rMBs. To date, the successful Mg 2+ -intercalation was only achieved in only a few cathode hosts, one of which is manganese dioxide. This review summarizes the research activity of studying MnO2 in magnesium cells. In recent years, the cathodic performance of MnO2 was impressively improved to the capacity of >150-200 mAh g −1 at voltage of 2.6-2.8 V with cyclability to hundreds or more cycles. In addition to reviewing electrochemical performance, we sketch a mechanistic picture to show how the fundamental understanding about MnO2 cathode has been changed and how it paved the road to the improvement of cathode performance.

Manganese‐Oxide‐Based Electrode Materials for Energy Storage Applications: How Close Are We to the Theoretical Capacitance?

“…In parallel to the applications as electrodes in supercapacitors discussed above, MnO x ‐based materials have been studied as both cathodes and anodes in various rechargeable ion batteries, such as Li, Na, Mg, and Zn ion batteries. Unlike in a supercapacitor, there are more factors that affect the overall electrochemical performances of a battery, besides the electrode material itself.…”

“…Another type of rechargeable batteries is the Mg ion batteries in which α‐MnO 2 cathode showed higher voltage of 1.5 V versus Mg and higher initial capacity of 280 mA h g −1 than conventional Chevrel phase cathodes . In particular, magnesiation process in MnO x ‐based cathode is limited not only by the nanostructure of MnO x and surface reactions but also by other kinetically slow processes …”

A High‐Rate Rechargeable Mg Battery Based on AgCl Conversion Cathode with Fast Solid‐State Mg2+ Diffusion Kinetics

“…Furthermore, the strong interaction between bivalent Mg 2+ ions and cathode matrix would limit the rate performance to some extent . More seriously, the strong interaction usually leads to a collapse of intercalation cathode and amorphization of the material surface, blocking the Mg 2+ intercalation . Therefore, it is of great significance to explore new type of cathode materials.…”

“…Because of the bivalent nature and high charge density, Mg 2þ ions are difficult to intercalate into most cathodes, resulting in quite limited Mg-storage cathode options and low specific capacities. [7][8][9][10][11][12][13][14][15][16][17] Furthermore, the strong interaction between bivalent Mg 2þ ions and cathode matrix would limit the rate performance to some extent. [12][13][14] More seriously, the strong interaction usually leads to a collapse of intercalation cathode and amorphization of the material surface, blocking the Mg 2þ intercalation.…”

“…[12][13][14] More seriously, the strong interaction usually leads to a collapse of intercalation cathode and amorphization of the material surface, blocking the Mg 2þ intercalation. [8] Therefore, it is of great significance to explore new type of cathode materials. Electrochemical conversion reaction provides an alternative strategy to widen the options of Mg-storage cathode, since it is not essentially constrained by the crystal lattice, and thus various kinds of electrode materials could be selected to construct Mg batteries.…”