Multifunctional Separator Coatings for High-Performance Lithium–Sulfur Batteries

摘要

Electrochemical energy storage systems that are cost-effective, safe, environmentally friendly, and possess long cycle/shelf-life are needed in multiple fields of technology, including transportation, portable devices, robotics, and power generation from intermittent sources. Currently, Li-ion (150 Wh kg~(?1)) and Li-ion-polymer (180 Wh kg~(?1)) batteries~([1]) are the most promising storage platforms for many applications. It is understood however that the intercalation-based cathodes used in these technologies provide limited opportunities for the sort of advancement in specific energy required to keep pace with growing demand.~([2–4]) Replacing cathodes with conversion materials such as sulfur, oxygen, or carbon dioxide, removes these limitations, but introduces new challenges associated with dissolution, transport, and parasitic reactions between battery anodes and redox products in cathodes.~([2,5]) Lithium–sulfur (Li–S) battery is the most studied and arguably the most promising candidate for commercial use for at least three reasons: (i) The Li–S battery offers tenfold higher energy storage capacity (specific capacity 1675 mAh g~(?1) and theoretical energy density 2600 Wh kg~(?1)) than any of the commercial Li-ion batteries; (ii) sulfur is earth abundant and inexpensive ($0.02 g sulfur?1), leading to low-cost high-energy batteries;~([6,7]) and (iii) sulfur is environmentally benign, reacts spontaneously and reversibly with lithium.~([5,8,9]) Despite these benefit, Li–S cells suffer from poor cycling efficiency and short lifetimes stemming from the complex solution chemistry of lithium sulfide and lithium polysulfide (LiPS) products from the cathode.~([10–13]) The most successful efforts have been devoted to cathode configurations/ materials to provide physical confinement~([11,14,15]) and chemical adsorption~([16–18]) for LiPS to prevent its dissolution and uncontrolled redox reaction with lithium metal.