In early October, UK-based OXIS Energy announced that its lithium-sulphur (Li-S) cells had achieved 425Wh/kg using a high energy 16Ah pouch cell design for HAPS (High Altitude Pseudo Satellite) applications. It expects to reach 450Wh/kg by the end of 2018 and 500Wh/kg by the end of 2019 with the help of selected partners. OXIS Energy has also developed a prototype battery module for the aviation industry, with an aim to achieve a three-fold increase in flight time. This battery uses a high power, ultra-light Li-S pouch cell at 300Wh/kg. The high-power cells are estimated to reach 400 Wh/kg by 2019.
Li-S technology shows great potential, but further developments are needed before products make a large commercial impact. One focus is on improving Li-S battery life-cycle. Li-S batteries have higher energy density, higher theoretical capacity and lower production costs than current NCM lithium-ion batteries. Li-S batteries allow for a theoretical specific energy of more than 2700Wh/kg. Much of the recent development in the electric vehicle (EV) battery industry has been concerned with improving energy density. In order to achieve longer vehicle driving ranges, higher energy density is desperately required in the battery. In addition, sulphur is abundant, with sufficient raw material supply, and the lightweight nature of sulphur is an added benefit to battery design.