A high-voltage and low-solvating electrolyte towards promising micro-Si/Ni-rich NMC full cells

Abstract

A full cell via pairing high-capacity silicon anode with high-voltage NMC cathode (Li(Ni0.83Co0.12Mn0.05)O2) holds great promise as a high-energy battery system for practical applications. Nevertheless, this potential has been hindered by challenges in terms of the pulverization of Si particles, unstable electrode/electrolyte interface, and severe dissolution of transition metals at high voltage. Herein, we present a novel high-voltage and weakly solvating electrolyte, consisted of lithium bis(fluorosulfonyl)imide in mixed solvent of diethyl carbonate and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, which effectively enables the remarkable cycling stability of both micron silicon anode (a high reversible capacity of 1667 mAh g−1 after 200 cycles) and Ni-rich cathode (a notable capacity retention of 83% after 140 cycles at an ultrahigh cut-off voltage of 4.9 V). It is revealed that the tailored electrolyte leads to the formation of a robust and reinforced concrete-like solid electrolyte interphase, characterized by a distinctive vertical side-by-side columnar structure comprised of LiF and sulfide on the micro-silicon anode. Meanwhile, a uniform and thin cathode-electrolyte interphase is observed on the surface of NMC particles when cycled in the designed electrolyte. Furthermore, coupled with high-capacity micro-Si and high-voltage NMC, this designed electrolyte endows a remarkable full-cell with high energy density (475 Wh kg−1), excellent rate capability, and high-voltage cycling stability. This research contributes a pioneering approach to enabling the utilization of micron-sized silicon anodes and Ni-rich cathodes for next-generation high-energy lithium-ion batteries.