At the Spring 2015 Materials Research Conference in San Francisco earlier this month, PATHION presented two new derivative superionic solid-state electrolytes built upon LiRAP (Lithium-Rich Anti-Perovskite). PATHION has an exclusive worldwide license for LiRAP from Los Alamos National Laboratories. Supported by an ARPA-E grant, LiRAP has proven to be a safe alternative compared to the liquid electrolytes used in most of today’s lithium ion batteries.
Solid-state electrolytes, unlike liquid-state, have extremely low expansion, no out-gassing, and the elimination of dendrite growth between anode and cathode, although sometimes at the expense of performance. The LiRAP solid electrolytes conduct Li+ ions well at high voltage and high current, providing much enhanced energy density and power capacity as well as safety. PATHION is working on a derivative for Li-sulfur batteries as well as a derivative that could be applied in a sodium-ion battery.
Lithium sulfur. The first PATHION presentation described the role of LiRAP in a solid-state lithium-sulfur electrolyte. Barriers to commercialization of high energy density Li-sulfur batteries are fast capacity fading (stability) and low cycling efficiency mainly due to a complicated reaction mechanism which involves different soluble lithium polysulfides.
A doped or optimized Li3ClO-based glass electrolyte can serve as a barrier to halt the diffusion of polysulfides into the lithium. Besides using the doped or optimized Li3ClO-based glass electrolyte, PATHION also prepared a highly efficient sulfur cathode which allows for an increased sulfur loading of up to 6.9 mg cm-2.
In combination, this cathode and electrolyte have resulted in a significant improvement in charge efficiency with a longer cycle life. Such a lithium sulfur battery could achieve specific energy levels up to 800 Wh/kg, compared to about 250 Wh/kg from the best commercial Li-ion cells today. In addition, the new lithium sulfur-based material can be applied either in a battery or a supercapacitor.
LiGlass. The second presentation described the use of a solid electrolyte in a sodium-ion battery cell. On a performance basis, LiGlass exhibits ultrafast ionic conductivities at room temperature and up to 200°C, which can lead to energy densities that exceed 1,000 Wh/kg.
PATHION technology executive Andy Murchison led these development efforts with the support of Helena Braga and Jorge Ferreira of the University of Porto, who were operating under a work-for-hire agreement with PATHION.
LiRAP. Researchers at Los Alamos originally proposed a novel class of superionic solid electrolyte made of lithium rich anti-perovskites (LiRAP) to work with metallic Li-anodes and readily rechargeable cathodes. The new materials feature immense Li+ vacancies and lattice imperfections in the crystal lattice for fast ionic transporting with low energy barriers.
The principal investigators at Los Alamos invented novel lithium-rich compounds—Li3OCl, Li3O(Cl,Br) and related anti-perovskites that demonstrated 3D superionic conductivity, a broad working window, economic viability, and environmental friendliness.
M.H. Braga, J.A. Ferreira, V. Stockhausen, J.E. Oliveira, A. El-Azab (2014) “Novel Li3ClO based glasses with superionic properties for lithium batteries” J. Mater. Chem. A 2, 5470-5480 doi: 10.1039/C3TA15087A
Xujie Lü, Gang Wu, John W. Howard, Aiping Chen, Yusheng Zhao, Luke L. Daemena and Quanxi Jia (2014) “Li-rich anti-perovskite Li3OCl films with enhanced ionic conductivity” Chem. Commun., 50, 11520-11522 doi: 10.1039/C4CC05372A