Recent progress on iron- and manganese-based anodes for sodium-ion and potassium-ion batteries

Nowadays, energy storage plays an important role in the mobile electronic devices, all kinds of electrical vehicles and grid-scale renewable energy storage intermediates. Since the limited sources of lithium and its skyrocketing price in recent years, the rechargeable sodium ion batteries (SIBs) and potassium ion batteries (PIBs) have attracted a great many studies due to the unlimited sources of sodium and potassium in the ocean. And the development of electrode materials and electrolytes of SIBs/PIBs are very important to better smoothly integrating the renewable resources over large-scale energy storage systems (EESs). The earth abundant iron-/manganese-based anodes are ideal candidates for further reducing the prices of electrodes with more potential practical in SIBs and PIBs. In this review, recent progresses on the low cost iron-/manganese-based anode materials, including the oxides, fluorides, sulfides, phosphides, nitrides, etc., are summarised. In addition, comprehensive and integrated explanations of the structure-function-performance relationship of these composites/compounds and constructive suggestions towards obtaining better electrochemical properties and exceptional structure designs are reasonably proposed with their existing merits and shortcomings. We believe that more comprehensive explorations of these high abundant and low-cost Fe-/Mn-based anodes will surely boost the real applications of SIBs and PIBs in the near future.