Electrochemically Regulated Li Deposition by Crown Ether.

Abstract

The lithium-secondary battery is considered to be the most prospective electrochemical energy storage in the upcoming decades. However, its real application still much depends on the effective strategy toward Li dendrite growth. After years of effort, many successful works have been reported on improving the solid-electrolyte interphase (SEI), either via electrolyte optimization or building artificial SEI while intrinsically adjusting the electrochemical reduction of Li+ has been rarely mentioned. Inspired by the successful works in the electroplating industry, in this paper, a Li-chelating agent, benzo-15-crown-5 (B15C5) was used to regulate Li-reduction kinetics from an electrochemical view. Owing to the coordination with Li+, Li+ + complex + e- → Li[complex] is generated and proved by a decreased i0 value. B15C5 confined within the PVC matrix has been coated on a Li anode. With thus-obtained B15C5-PVC-Li, dendrite growth has been significantly reduced and prolonged cycling has been observed in Li|Li symmetric cells. Electrochemically modulated Li deposition has been further accessed by the full cell of LiFePO4|Li, and 163 mA h/g capacity is stably released after 400 cycles at 1.0 mA/cm2. This study provides an alternate approach to address the dendrite growth issue and sheds more light on the Li-deposition kinetics.