Cycling　lifespan/stability　is　one　of　the　most　important　limitations　for　multivalent　transition　metal　sulfides　(TMSs)　used　in　secondary　batteries.　However,　the　chaos　reaction　of　TMSs　is　an　important　obstacle　that　restricts　their　electrochemical　stability　in　all-enclosed　batteries.　Herein,　taking　FeS　anode　and　lithium-ion　batteries　as　the　example,　the　phase-lithiation　correlation　is　studied　through　TEM　and　DFT　analysis.　It＇s　found　that　the　pristine　hexagonal　FeS　converts　to　tetragonal　FeS　phase　accompanied　by　severe　and　rapid　capacity　decay.　However,　it　converts　to　orthorhombic　FeS　with　enhanced　capacity　and　nice　lifespan　when　introducing　trace　amount　amorphous　Al2O3　upon　FeS　power＇s　surface.　DFT　calculations　further　reveal　that　Al2O3　induces　the　phase　conversion　from　low-acitve　tetragonal　FeS　to　high-active　orthorhombic　FeS,　which　promotes　the　lithiation-delithiation　reversibility　and　stability.　Based　on　the　above　result,　it　is　expected　to　provide　useful　guidelines　for　the　in-situ　structure　engineering　of　TMSs-based　anodes　in　all-enclosed　secondary　batteries.