A Mechanochemically‐Triggered, Self‐Powered Flash Heating Synthesis of Phosphorous/Carbon Composites for Li‐Ion Batteries

"Flash heating" that transiently generates high temperatures above 1000 °C has great potential in synthesizing new materials with unprecedently properties. Up to now, the realization of "flash heating" still relies on the external power, which requires sophisticated setups for vast energy input. In this study, a mechanochemically triggered, self-powered flash heating approach is proposed by harnessing the enthalpy from chemical reactions themselves. Through a model reaction between Mg₃N₂/carbon and P₂O₅, it is demonstrated that this self-powered flash heating is controllable and compatible with conventional devices. Benefit from the self-powered flash heating, the resulting product has a nanoporous structure with a uniform distribution of phosphorus (P) nanoparticles in carbon (C) nanobowls with strong P─-C bonds. Consequently, the P/C composite demonstrates remarkable energy storage performance in lithium-ion batteries, including high capacity (1417 mAh g^-1 at 0.2 A g^-1), robust cyclic stability (935 mAh g^-1 at 2 A g^-1 after 800 cycles, 91.6% retention), high-rate capability (739 mAh g^-1 at 20 A g^-1), high loading performance (3.6 mAh cm^-2 after 100 cycles), and full cell cyclic stability (90% retention after 100 cycles). This work broadens the flash heating concept and can potentially find application in various fields.