Transition-metal oxides and chalcogenides with and 3-dimensional layered structures have been extensively investigated as cathodes for lithium secondary batteries. However, few studies have focused on intercalation host compounds containing the (XO_(m))^(n-) polyanions (e. g., X = Mo, W, S, P, and B) in place of the smaller O^(2-). Recently, raremetal-free materials and complexes with polyanions have been proposed as new candidates for the next generation cathodes/anodes. In this material group, the promising cathode/anode performances of NASICON-type Li₃Fe₂(PO₄)₃, olivine-type LiFePO₄, and calcite-tye FeBO₃ are presented. The aim of this study further the develo㎛ent of a multivalent-ion battery using Mg^(2+) or Ca^(2+) and an all polyanionic solid-state battery comprised of a polyanionic cathode, electrolyte, and anode.