Sulfur-Rich Cathode Materials for High-Energy Batteries

1. CNMS User Project Highlight Sulfur-Rich Cathode Materials for High-Energy Batteries • Achievement • A family of new lithium polysulfidophosphate (LPSP) compounds enables stable cycling of all-solid-state lithium-sulfur (Li-S) batteries with long lifespans. The excellent cyclability demonstrated in this research is attributed to the high ionic conductivity of LPSP, which is 107 times higher than Li2S, the most conductive species in conventional sulfur cathodes. • Significance • Li-S batteries have a high theoretical energy density 5 times higher than that of the lithium-ion batteries. Although promising, Li-S batteries have an intrinsic short lifespan. The all-solid-state Li-S overcome the cycle-life limit of the S cathode and imparts the safe cycling of metallic lithium anode. • Research Details • CNMS Capability: Synthesis and characterization of cathode materials; battery testing. • Li3PS4 reacts with elemental S and yields lithium polysulfidophosphate (LPSP) compounds with a general formula of Li3PS4+n (0<n<9). • LPSP compounds are superionic conductors. The log scale of the ionic conductivity (log σ) of LPSP follows a linear relationship with the number of sulfur atoms (n). • All-solid-state batteries have an excellent cycling performance with a cell configuration of LPSP as the cathode, Lithium metal as the anode, and Li3PS4 as the electrolyte. Figure 1. Cycling performance of an all-solid-state Li-S battery using LPSP as the cathode material. Figure 2. Temperature dependency of ionic conductivity of Li3PS4+5 and Li2S. Zhan Lin, Zengcai Liu, Wujun Fu, Nancy J Dudney, and Chengdu Liang Angewandte Chemie-International Edition, DOI: 10.1002/anie.201300680 Work was performed at CNMS and MSTD in ORNL

2. CNMS User Project Highlight Inexpensive, High-Energy Batteries Achievement A new family of lithium polysulfidophosphate (LPSP) compounds has been discovered for high energy lithium-sulfur batteries. The battery uses solid electrolytes that are intrinsically safer than the liquid electrolytes used in conventional lithium-ion batteries. The new battery structure last longer than conventional batteries. Significance and Impact Harvesting of intermittent renewable energies to a stable supply of electricity needs large scale storage of electricity that are safe, low cost, and high energy-density. Long-lasting lithium-sulfur battery technology has been demonstrated based on a low –cost material of elemental sulfur. The all-solid-state configuration ensures a safe operation of battery. Research Details Li3PS4 reacts with elemental S and yields lithium polysulfidophosphate (LPSP) compounds with a general formula of Li3PS4+n (0<n<9). The lithium-ions are highly mobile in this new family of compounds. The high ionic conductivity of these compounds enables a long cycle-life of lithium-sulfur batteries. Figure 1. Cycling performance of an all-solid-state Li-S battery using LPSP as the cathode material. Figure 2. Temperature dependency of ionic conductivity of Li3PS4+5 and Li2S. Zhan Lin, Zengcai Liu, Wujun Fu, Nancy J Dudney, and Chengdu Liang Angewandte Chemie-International Edition, DOI: 10.1002/anie.201300680 Work was performed at CNMS and MSTD in ORNL