Manganese　(Mn)-based　lithium　(Li)-ion　batteries　with　high　energy　density　and　low　cost　have　recently　attracted　considerable　attention.　One　drawback　of　Mn-based　batteries　is　the　severe　capacity　attenuation　caused　by　the　Jahn-Teller　effect,　which　distorts　the　crystal　structure　and　reduces　the　kinetics　of　Li-ion　insertion/extraction　in　the　cathodes.　In　this　study,　the　Mn　valence　state　is　regulated　on　the　surface　of　Mn-based　oxide　particles　and　oxygen　vacancies　are　introduced　to　facilitate　rapid　Li-ion　transport　and　charge　storage　by　adding　succinonitrile　(SN)　to　Mn-based　cathodes.　Because　of　the　reaction　between　SN　and　Mn-based　cathode　particles,　the　contents　of　Mn3+　ions　and　oxygen　vacancies　increase,　leading　to　an　improvement　in　the　Li-ion　kinetic　properties　of　the　cathodes　as　well　as　a　reduction　in　the　dissolution　of　Mn　from　the　cathodes.　By　regulating　the　Mn　valence　state,　Li-ion　and　Li　metal　batteries　with　LiMn2O4　or　Li-rich　Mn-based　layered　oxide　cathodes　show　significantly　enhanced　discharge　capacity　and　improved　cyclic　performance.　This　study　demonstrates　that　regulating　the　valence　state　of　Mn　ions　is　an　effective　strategy　for　enhancing　the　electrochemical　performance　of　Mn-based　Li　batteries　and　that　adding　SN　to　the　cathodes　is　a　cost-effective　method　for　mass　production.　The　reaction　between　succinonitrile　and　the　Mn-based　oxide　particles　in　the　cathode　reduces　the　valence　state　of　Mn　ions　and　induces　more　oxygen　vacancies　on　the　surface　of　the　oxide　particles,　facilitating　rapid　Li-ion　transport　and　decreasing　Mn　dissolution;　therefore,　the　discharge　capacity　and　cycle　performance　of　the　Mn-based　cathodes　are　significantly　enhanced.　image