Nonequilibrium Thermal Shock Enabled Trapping of Metastable Multi-Element Alloy Anode for Potassium-Ion Batteries

Metastable multi-element nanoalloys hold extensive potential for next-generation batteries due to their distinct structures. However, it is difficult to obtain metastable nanoalloys through conventional equilibrium annealing. Herein, the rapid nanomanufacturing of metastable multi-metallic nanoalloys is reported with single-phase structure, ultrafine size distribution, and high-density dispersion, realized by a novel nonequilibrium thermal shock (NTS) method. The NTS method, which features ultrafast heating/cooling rates and ultrashort treatment duration, can lead to the uniform mixing of different elements and the capture of the metastable state of multi-element nanoalloys while preventing interparticle sintering/coarsening and phase separation. As a proof-of-concept demonstration, a metastable BiSnSb nanoalloy (M-BiSnSb), prepared by the NTS method, exhibits rich lattice distortions and superior performance for potassium ion batteries (KIBs) compared with the stable BiSnSb (S-BiSnSb) anode prepared by a typical equilibrium method. Additionally, in situ high-temperature synchrotron X-ray diffraction (SXRD) demonstrates the formation mechanism of M-BiSnSb. Furthermore, in situ laboratory X-ray diffraction (XRD) and molecular dynamics (MD) simulation systematically prove the alloying reaction mechanism and the structural advantages of the metastable nanoalloys in diffusion-accelerating effect, respectively. This nonequilibrium nanomanufacturing strategy is expected to enable the rational and controllable synthesis of metastable nanomaterials for extensive electrochemical energy applications.