Li-argyrodite　electrolytes　have　attracted　special　attention　as　the　promising　candidate　for　all-solid-state　batteries　considering　its　high　ionic　conductivity　and　relative　stability.　However,　the　interfacial　compatibility　issues　associated　with　PS43-　tetrahedra　decomposition　led　to　dendrite　growth　and　rapid　battery　failure　in　integrating　the　lithium　metal　anode.　Herein,　in　situ　electrochemical　(de)lithiation　of　Li6PS5Cl　coated　with　Mg(ClO4)2　(LPSC-MCO)　induced　by　metastable　decomposition　is　proposed　to　mitigate　undesirable　reactions　at　lithium　anode　through　atomic　coordination　and　electron　relocalization.　The　inhibition　of　electrochemical　decomposition　for　PS(4)3(-)　tetrahedra　is　due　to　the　formation　of　PS3O3-　and　the　components　regulation　from　Li2S　and　Li3P　to　Li2O,　LiCl　in　solid　electrolyte　interphase.　Additionally,　the　ab　initio　molecular　dynamics　(AIMD)　and　density　functional　theory　(DFT)　analysis　are　utilized　to　uncover　the　fundamental　mechanism　behind　the　interactions　of　Li-O　and　Li-Cl　and　electron　redistribution　around　O,　Cl,　and　Mg.　A　high　critical　current　density　of　1.9　mA　cm-2　and　stable　lithium　plating/stripping　behaviors　over　2300　h　are　presented　to　verify　the　suppression　for　lithium　dendrite　and　the　NCM/LPSC-MCO/Li　cell　consequently　exhibits　excellent　performance.　It　inspires　new　pathways　of　probing　into　atom　coordination　and　electron　relocalization　to　address　(electro)chemical　decomposition　and　dendrite　issues　in　all-solid-state　batteries.