A high-performance lithiated silicon–sulfur battery enabled by fluorinated ether electrolytes

Abstract

Lithiated silicon–sulfur (Si–S) batteries are an attractive energy storage system that can offer higher theoretical energy density and lower cost than current lithium-ion batteries. However, this type of battery using conventional ether electrolytes suffers from a short lifespan, resulting from poor anode stability and severe polysulfide shuttle effects. To tackle these challenges, here we report a fluorinated ether electrolyte to boost the performance of lithiated Si–S batteries. The newly developed electrolyte not only enables the formation of a robust solid-electrolyte interphase on the Si surface, which effectively accommodates volume variation, thus stabilizing the Si anode, but also leads to quasi-solid-state conversion of S species, thereby considerably mitigating the polysulfide shuttle effect. As a result, a Si–S full battery using the fluorinated electrolyte is able to deliver a high initial capacity of 902 mA h g⁻¹ and maintain capacity retention of 64.0% after 100 cycles. By contrast, the capacity of a cell using conventional ether electrolyte rapidly decays to 162 mA h g⁻¹, which is only 17.5% of its original value. More impressively, for the first time, we demonstrate that a full cell can operate stably with a high cathode loading (6.2 mg cm⁻²) and lean electrolyte (<10 μL mg⁻¹), showing great potential for achieving high-performance and high-energy batteries.