Improved battery cycling by alloy engineering: A medium high-entropy alloy, BiSbSe_1.5Te_1.5, is used to showcase how increased entropy can reduce the propensity of electrode pulverization and improve the cycling stability of conversion-alloying anodes – and this without compositing with any carbonaceous materials. The structural evolution of BiSbSe_1.5Te_1.5 during (de)lithiation is followed by operando X-ray diffraction.

Abstract

One often proposed route to improved energy density for lithium-ion batteries is to use alloy anodes, such as silicon, able to store large amounts of lithium. Mechanical instability caused by the large expansion and contraction associated with (de)lithiation, and hence bad cyclability, has, however, so far hindered progress. As proof-of-concept of a remedy, we here present BiSbSe_1.5Te_1.5, a medium high-entropy alloy with improved cycling stability for conversion-alloying (de)lithiation reactions. We attain five to twenty times more stable cycles than previously reported for comparable metal-Se and -Te-based anodes, with a very good reversible capacity (464 mAh g⁻¹) for up to 110 cycles- and this without using any carbonaceous materials to create a composite. Altogether, this highlights how alloy engineering and increased entropy materials can stabilize conversion-alloying electrodes.