Lithium-Sulfur Batteries with Robust Cycle Life For Space Applications

Abstract

While lithium-ion (Li-ion) batteries offer tremendous performance advantages over their battery predecessors (e.g., nickel-cadmium, lead-acid), they are approaching an asymptotic limit in specific energy (~250 Wh/kg at cell level) and do not adequately address next generation space platform requirements (e.g., by NASA [1]). As a result, there has been intense research and development (R&D) on higher specific energy batteries that have been coined beyond Li-ion. Rechargeable lithium-sulfur (Li-S) battery is a particularly attractive beyond Li-ion battery chemistry because it offers a high theoretical specific energy of 2500 Wh/kg (at materials level) [2] and a demonstrated practical specific energy >300 Wh/kg (at cell level) [3], making it a promising battery chemistry for future space applications that demand higher specific energy in batteries.Currently, no commercial Li-S battery exists due to several significant technical challenges that have thus far prevented the realization of the Li-S chemistry’s tremendous performance potential. These technical challenges include: (i) Low practical energy yield and significant capacity loss with cycling, due to lithium polysulfide formation/dissolution/migration during discharge [4]. (ii) High self-discharge rates and low Coulombic efficiency, due to redox shuttle reactions of the dissolved polysulfides. (iii) Safety concerns, mainly due to Li dendrite growth from the unprotected Li anodes [5].We will present our efforts in the development of a high energy density, long cycle life, long shelf life and enhanced reliability/safety Li-S battery technology, using a holistic and comprehensive approach to overcome technical challenges that hinder commercialization of Li-S batteries. In particular, we will demonstrate impact of various battery testing parameters, such as depth-of-discharge, charge/discharge current C-rate, on Li-S cell cycle performance and shelf life.Our investigation results showed that, using material engineered (active and inactive) cell components, the resultant Li-S cells demonstrated excellent cycle life performance, while achieving high specific capacities and energies when cycled under optimized battery testing schemes. The advanced Li-S battery technology has shown a great promise to achieve unprecedented specific energy/energy density and long-term cycle/shelf life stability for future space applications. References 2020 NASA Technology Taxonomy, https://www.nasa.gov/offices/oct/taxonomy/index.htmlZhang, Sheng S., Power Sources, 231, 153-162, 2013.Weibing Xing, # A02-0364, 238th Electrochemical Society Meeting (PRiME), Honolulu, HI, October 4-9, 2020.Besenhard JO. Handbook of Battery Materials. Wiley: New York; 1998.James R. Akridge, Battery Power Products & Technology, October 2001. Acknowledgement We would like to acknowledge financial support from NASA Glenn Research Center for this R&D work.