Additive-Assisted Hydrophobic Li+ -Solvated Structure for Stabilizing Dual Electrode Electrolyte Interphases through Suppressing LiPF6 Hydrolysis.

Abstract

Lithium-metal batteries have attracted much attention due to their high energy density. However, the hydrolysis of LiPF6 leads to uncontrollable Li dendrites growth and fast capacity fading. Herein, a hydrophobic Li+ -solvated structure is designed by inducing the hexafluoroisopropyl acrylate into the electrolyte system. Due to the alkene groups and non-polar perfluorocarbon (-CF2 CF2 CF3 ) chain, a hydrophobic surface around Li-ion solvated aggregates can be obtained to protect the LiPF6 against the attack from trace H2 O. Moreover, the additive could also help to form an organic solid electrolyte interphase with rich polar C-F bonds, which can capture Li ions to restrain the dendrite growth. Therefore, the Li||Li symmetric cells show a stable cycling performance up to 500 h at a current density of 1 mA cm-2 . The Li||LiNi0.6 Co0.2 Mn0.2 O2 cells show good cycling stability, exhibiting a specific capacity of 111 mAh g-1 at 1 C with a capacity retention of 74 % after 200 cycles.