Achieving long cycle life for all-solid-state rechargeable Li-I2 battery by a confined dissolution strategy

Abstract

Rechargeable Li-I₂ battery has attracted considerable attentions due to its high theoretical capacity, low cost and environment-friendliness. Dissolution of polyiodides are required to facilitate the electrochemical redox reaction of the I₂ cathode, which would lead to a harmful shuttle effect. All-solid-state Li-I₂ battery totally avoids the polyiodides shuttle in a liquid system. However, the insoluble discharge product at the conventional solid interface results in a sluggish electrochemical reaction and poor rechargeability. In this work, by adopting a well-designed hybrid electrolyte composed of a dispersion layer and a blocking layer, we successfully promote a new polyiodides chemistry and localize the polyiodides dissolution within a limited space near the cathode. Owing to this confined dissolution strategy, a rechargeable and highly reversible all-solid-state Li-I₂ battery is demonstrated and shows a long-term life of over 9000 cycles at 1C with a capacity retention of 84.1%.

Rechargeable Li-I₂ battery system is interesting due to high theoretical capacities but the insoluble discharge product at the conventional solid interface leads to poor performances. Here, by using a confined dissolution strategy the authors demonstrate a rechargeable all-solid-state Li-I₂ battery with extended cycle life.