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

Abstract 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.