In　a　conventional　roasting-sorting　process　to　obtain　cathode　powders,　the　phase　structure　of　LiMn2O4　is　not　dissociated　and　the　valence　of　manganese　is　not　changed,　resulting　in　low　metal　recovery　efficiency　and　high　reagent　cost　in　the　subsequent　leaching　process.　In　this　context,　a　novel　process　is　developed　to　realize　the　recovery　of　spent　LiMn2O4　lithium-ion　batteries　(LIBs)　via　one-step　pyrolysis　and　reductant-free　acid　leaching.　The　leaching　efficiencies　of　lithium　and　manganese　are　respectively　99.9%　and　99.4%　under　the　optimal　pyrolysis　conditions:　a　temperature　of　500　degrees　C,　a　nitrogen　flow　rate　of　50　mL/min,　and　a　pyrolysis　time　of　60　min.　The　analysis　of　thermogravimetry-infrared　spectroscopy　indicates　volatilization　of　electrolyte　and　decomposition　of　LiPF6　occur　in　the　temperature　range　of　100-180　degrees　C.　When　the　temperature　rises　from　180　to　800　degrees　C,　high　molecular　weight　polymers　(binder　and　separator)　are　degraded　into　pyrolytic　gas　and　oil.　LiMn2O4　is　deconstructed　and　reduced　to　MnO　and　Li2CO3　under　the　synergistic　effect　of　pyrolytic　gas　and　anode　graphite.　The　harmful　fluorine　and　phosphorus　are　absorbed　by　Ca(OH)2　solution　to　avoid　environmental　hazards.　The　results　suggest　that　the　process　integrated　pyrolysis　and　aicd　leaching　is　efficient,　environmental-friendly,　and　low-cost　for　recycling　spent　LiMn2O4　LIBs.