KISTI Institutional Repository: Ab Initio Study of the Sodium Intercalation and Intermediate Phases in Na0.44MnO2 for Sodium-Ion Battery

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dc.identifier.uri: http://www.ndsl.kr/ndsl/search/detail/article/articleSearchResultDetail.do?cn=NART62231258

dc.description.abstract: TheNa0.44MnO2structureisapromisingcathodematerialforsodiumionbatteriesduetoahighcapacity(130mAh/g)andgoodcycleperformance.Inthiswork,wepresenttheresultsofdensityfunctionaltheory(DFT)calculationsonthestructuralandelectrochemicalpropertiesofNa0.44MnO2,combinedwithexperiments.Sevenintermediatephasesandthetwo-phasereactionsamongthemwerefound,wherethecalculatedvoltageprofileagreedwellwithexperiments.WefoundthattheS-shapedtunnelisnotemptyinthedeintercalatedNa0.22MnO2structurebuthasapartialoccupancyofsodiumions.Thenewsodiumsiteswerefoundinalimitedsodiumcompositionrange(x=0.44.55)whichisattributedtotheelectrostaticinteractionsbetweensodiumionsandmanganeseatoms.TheasymmetriclatticeevolutioninNa0.44MnO2asafunctionofsodiuminsertion/deinsertionisshowntobeduetotheJahn？Tellereffects.Onthebasisofthisinterpretation,wesuggestthattheCrsubstitutionwillreducethevolumechangesignificantly.