Addressing Mn Dissolution in High-Voltage LiNi_(0.5)Mn_(1.5)O_4 Cathodes via Interface Phase Modulation

摘要

Spinel LiNi_(0.5)Mn_(1.5)O_4 (LNMO), high-voltage and high-power density, is avery promising cathode candidate. Nevertheless, its lack of cycling stabilityhas historically been long accepted as an inherent issue. Based on theabove problem, a strategy is initiated to directly address Mn dissolution andunstable interface structure. A beneficial solid-phase reaction occurs at theLNMO interface, transforming the spinel phase into two functional phases.One is the layered phase that provides electrochemical activity and supportscharge transport. The other is the rock-salt like phase induced by Li/Mnexchange that can inhibit the dissolution of Mn and provide inert protection.The Li/Mn exchange structure increases the diffusion energy barriers of Mn,which restrains the loss of Mn, proven by the bond valence sum calculation.The two phases are modulated successfully at the LNMO interface to balancethe stable material structure and excellent charge transfer, obtaining a samplewith excellent electrochemical performance. The capacity retention rate ofmodified LNMO is 15 higher than that of the pristine sample after 500cycles. The preparation method does not utilize any dopants or coatings andcan play a guiding role in addressing issues regarding structural stability andelectrochemical performance for cathode materials.