New Insight for Surface Chemistries in Ultra-thin Self-assembled Monolayers Modified High-voltage Spinel Cathodes.

ABSTRACT: The electrochemical properties of the interface between the spinel LiNi_0.5Mn_1.5O_4-? (LNMO_4-?) cathodes and ethylene carbonate-dimethyl carbonate (EC-DMC) electrolyte containing 1?M of LiPF₆ have been investigated to achieve high-voltage durability of LNMO_4-?/graphite full cells. Coating the LNMO_4-? crystal surface by a fluoroalkylsilane self-assembled monolayer with a thickness below 2?nm resulted in a capacity retention of 94% after 100 cycles at a rate of 1?C and suppression of capacity fading for both the cathode and anode of the full cell. The observed effect is likely caused by the inhibited oxidative decomposition of EC-DMC electrolyte and vinylene carbonate (VC) species at the LNMO_4-? crystal surface and formation of a stable VC solid electrolyte interface near the anode. Moreover, the results obtained via photoelectron spectroscopy and density-functional calculations revealed that the increase in the work function of the LNMO_4-? crystal surface due to the formation of Si-O-Mn species primary contributed to the inhibition of the oxidative decomposition of the electrolyte and VC molecules at the cathode/electrolyte interface.

SUBMITTER: Kim DW 

PROVIDER: S-EPMC6079065 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature