Researchers at French battery-maker Saft and Université Paris Est have, for the first time, used a nanocomposite metal hydride as the anode in a complete solid-state battery with a sulfur cathode and LiBH4 electrolyte.
In “An all-solid-state metal hydride-Sulfur lithium-ion battery,” published in the Journal of Power Sources, Pedro López-Aranguren and colleagues explain that their cell shows a high reversible capacity of 910 mAh g−1 with discharge plateaus at 1.8 V and 1.4 V. Capacity remains at 85% of the initial value over the 25 first charge/discharge cycles.
“Lithium-sulfur (Li-S) batteries are one of the most attractive candidates for the next generation of high-energy rechargeable Li batteries because of their high specific energy at a working voltage of ca. 2.2 V,” write López-Aranguren et al. “For the assembly of Li-S batteries, metallic Li as negative electrode is commonly paired with S as positive active material due to their high theoretical capacities. However, the use of metallic Li deals with serious safety hazards as fire or explosion of the battery, thus considering its substitution by high capacity anodes as an interesting approach.”
“Metal hydrides have been proposed as breakthrough negative electrode materials. These hydrides exhibit excellent performance in half all-solid-state (ASS) cells with LiBH4 as solid electrolyte (SE) and metallic Li as anode. However, their implementation as negative active materials in complete cells has not been yet accomplished.”
“It is necessary to find suitable lithium-based positive materials with similar theoretical capacities and chemical compatibility with the electrolyte to pair them. In this context, the S/Li2S redox couple appears to be an ideal candidate. Indeed, it has been shown to offer an excellent compatibility and performance in ASS batteries using LiBH4 as solid electrolyte (~800 mAh g-1 after 50 cycles). From this inspiring background, we decided to evaluate the performance of MH anodes with the S/Li2S couple integrated in an ASS battery. This is, to the best of our knowledge, the first high-capacity all-solid-state battery using metal hydrides as anode.”