Abstract
The interfacial instability of the lithium-metal anode and shuttling of lithium polysulfides in lithium-sulfur (Li-S) batteries hinder the commercial application. Herein, we report a bifunctional electrolyte additive, i.e., 1,3,5-benzenetrithiol (BTT), which is used to construct solid-electrolyte interfaces (SEIs) on both electrodes from in situ organothiol transformation. BTT reacts with lithium metal to form lithium 1,3,5-benzenetrithiolate depositing on the anode surface, enabling reversible lithium deposition/stripping. BTT also reacts with sulfur to form an oligomer/polymer SEI covering the cathode surface, reducing the dissolution and shuttling of lithium polysulfides. The Li–S cell with BTT delivers a specific discharge capacity of 1,239 mAh g−1 (based on sulfur), and high cycling stability of over 300 cycles at 1C rate. A Li–S pouch cell with BTT is also evaluated to prove the concept. This study constructs an ingenious interface reaction based on bond chemistry, aiming to solve the inherent problems of Li–S batteries.
Highlights
The interfacial instability of the lithium-metal anode and shuttling of lithium polysulfides in lithium-sulfur (Li-S) batteries hinder the commercial application
In this work, we demonstrate that D-solid-electrolyte interfaces (SEIs) generated by the simple in situ interfacial reactions in the electrolyte containing BTT provide stable interfaces for the Li–S battery
The SEI film composed of S–Li suppresses Li dendrite growth, improves the Li+ conductivity, and possess a self-healing ability like a skin on the Li anode
Summary
The interfacial instability of the lithium-metal anode and shuttling of lithium polysulfides in lithium-sulfur (Li-S) batteries hinder the commercial application. It is plagued with two key barriers that limit its applications: interfacial instability of lithium-metal anode and shuttling of soluble intermediate polysulfides of the sulfur cathode[1] To tackle these problems, several techniques have been proposed, including: electrode modification, such as designing structured Li-metal anodes[2,3,4]; confining S within porous carbon or other nano-architectures with tailored surface[5,6,7]; electrolyte modification, such as using redox mediators and novel lithium salt/ionic liquid electrolyte[8,9,10,11,12,13,14]; electrode-electrolyte interface modification[15], such as constructing solid-electrolyte interphase (SEI) on the Li-metal surface[16,17,18,19,20,21,22,23]; and protective layers on the S cathode[24,25]. The in situ S–X (S or Li) bond formation and interfacial electrochemical transformation mechanism are investigated systematically
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