All-solid lithium-sulfur batteries: present situation and future progress

Lithium-sulfur (Li–S) batteries are among the most promising next-generation energy storage technologies due to their ability to provide up to three times greater energy density than conventional lithium-ion batteries. The implementation of Li–S battery is still facing a series of major challenges including (i) low electronic conductivity of both reactants (sulfur) and products (polysulfides) that limits the rate capability of the battery; (ii) high solubility of the polysulfide products into the electrolyte that affects the cycle life; and (iii) the reactivity of the lithium metal anode that induces serious safety hazards. Replacing hazardous organic electrolytes with solid-state electrolytes (SSEs) can prevent lithium polysulfides crossover and Li dendrite growth. SSEs with high ionic conductivity and good electrochemical stability can boost Li–S technology by improving electrochemical performance and cycling stability. All-solid lithium-sulfur batteries (SLSBs), comprising of sulfur cathode, solid electrolyte, and Li metal anode, are much safer than liquid-based electrochemical batteries such as conventional lithium batteries. They possess longer cycle life and require less effort in terms of packaging and monitoring circuits. SLSBs have the powerful ability to transfer the converted stored chemical energy into electrical energy with high efficiency and without the release of harmful gasses. This review focuses on the types of SSEs, their advantages and drawbacks in conjunction with Li–S batteries, and the challenges that hinder the practical application of SLSBs.