Due to the merits of low cost, low installation requirements, and high-level safety, aqueous rechargeable batteries (ARBs) offer an ideal option for dealing with future energy-demand pressure. Traditional aqueous batteries are mostly concentrated on mono-valent metal-ion, such as Li+, Na+,and K+. Compared to mono-valent carriers, multivalent cations have the capability to transfer more than one electron, and thereby to potentially provide better energy storage. To date, aqueous multivalent ion batteries based on Zn2+ have received a lot of attention. However, the investigations on aqueous Mg-ion batteries (MIBs) and Al-ion batteries (AIBs) still suffer from inadequate research despite the batteries' unique advantages.
Researchers led by Prof. Shengyang Dong at Nanjing University of Information Science and Technology (NUIST), China, are interested in guest pre-intercalation strategy to boost multivalent ion storage by optimizing the electronic structure, regulate the interplanar spacing, and improve the reaction kinetics of the host. They explored the topological Mg-ion/Al-ion storage characteristics of K-ion pre-intercalated MnO2 (KMO) as a favorable cathode material. The KMO cathode exhibits an enhanced reversible capacity of 185 mAh/g in 1 mol/L MgSO4 electrolyte. Even at an ultrahigh current density of 10 A/g, 78 mAh/g can be obtained. What's more, 86.7% capacity retention can be remained after 1000 cycles, exceeding the majority MnO2 cathode materials that have been reported. Additionally, KMO exhibits capability of Al3+ storage, implying the potential application in aqueous Al-ion batteries. They think that this work will broadens the potential applications of the multivalent-ion batteries for sustainable energy storage. The work entitled "Potassium ion pre-intercalated MnO2 for aqueous multivalent ion batteries" was published on Frontiers of Optoelectronics (published on Dec. 1, 2023).
