Elevating　the　cutoff　voltage　over　4.65　V　notably　augments　the　energy　density　of　LCO　batteries,　but　concomitant　irreversible　internal　structural　deterioration　and　serious　side　reactions　at　interface　accelerate　the　capacity　decay.　The　application　requirement　of　high-voltage　LCO　batteries　is　still　challenging.　Triphenylphosphine　selenide　(TPPSe)　served　as　multi-functional　additive　is　involved　in　the　electrolyte　to　concurrently　construct　stabilized　solid　electrolyte　interphase　(SEI)　and　cathode/electrolyte　interphase　(CEI)　films　and　enhance　the　durability　of　high-voltage　LCO　batteries,　benefited　from　the　distinctive　Se--P　group.　The　specific　Se--P　group　in　TPPSe　could　be　oxided　in　priority　at　cathode　side　to　form　SeOx　and　phosphate　to　enhance　the　high-voltage　stability　of　LCO,　and　reduced　at　anode　side　to　form　Li2Se　and　Li3P,　the　lithium　(Li)　metal　anode　is　well　protected.　Only　0.2　wt%　TPPSe　is　added　into　the　baseline　electrolyte,　the　discharge　capacity　of　LCO　batteries　is　improved　from　44　mAh　g-1　to　159　mAh　g-1　after　500　cycles　at　1　C　rate　in　the　voltage　range　of　3.0-4.65　V.　The　functioning　mechanism　is　revealed　by　XPS,　TOF-SIMS,　STEM,　AFM,　DEMS,　et.　al.,　combining　with　theoretical　calculation.　Furthermore,　10　wt%　FEC　and　1　wt%　HTCN　are　introduced　in　the　TPPSe-containing　electrolyte　to　powerfully　heighten　the　highvoltage　stability.　As　expected,　the　Li||LCO　pouch　cell　realizes　the　capacity　of　169　mAh　g-1　after　100　cycles　at　ultrahigh　cutoff　voltage　(4.7　V)　with　low　N/P　ratio　(1.19).　Such　an　effective　electrolyte-based　strategy　provides　promising　insight　into　the　exploitation　of　valuable　and　practical　electrolyte　additives　and　realization　of　highvoltage　LCO-based　batteries　with　superior　cycling　performance.