A solvent- and water-free flash Joule heating (FJH) method combined with magnetic separation is introduced for the recycling of spent cathode materials from lithium-ion batteries (LIBs). This method, called flash recycling, involves rapid heating to restore cathode structures and subsequent solid-state relithiation. The FJH process, which lasts only milliseconds, achieves high recovery yields (~98%) of battery metals, preserving the cathode's three-dimensional structure and enabling its reconstitution into new cathodes. The recycled cathodes exhibit electrochemical performance comparable to new commercial counterparts, demonstrating the effectiveness of the flash recycling process. Life cycle analysis shows that flash recycling offers significant environmental and economic benefits over traditional destructive methods, reducing energy and water consumption, greenhouse gas emissions, and operational costs. The flash recycling method is non-destructive, maintaining the cathode's bulk structure and allowing for the recovery of metals like lithium, cobalt, nickel, and manganese with high efficiency. The process involves flash Joule heating to induce carbothermal reduction, followed by magnetic separation to isolate ferromagnetic components. The non-ferromagnetic portion is then reprocessed for further recycling. The method is scalable and can be applied to various cathode chemistries, including LCO and NMC. The recycled cathodes show improved electrochemical performance, with high capacity retention and stability after multiple cycles. The flash recycling method also reduces metal impurities, such as Al and Cu, to levels below safety thresholds, ensuring the quality of the recycled materials. The process is energy-efficient, with significant reductions in water and energy consumption compared to traditional methods. Overall, flash recycling provides a sustainable and efficient solution for the recovery of cathode materials from spent LIBs, reducing environmental impact and enhancing resource efficiency.A solvent- and water-free flash Joule heating (FJH) method combined with magnetic separation is introduced for the recycling of spent cathode materials from lithium-ion batteries (LIBs). This method, called flash recycling, involves rapid heating to restore cathode structures and subsequent solid-state relithiation. The FJH process, which lasts only milliseconds, achieves high recovery yields (~98%) of battery metals, preserving the cathode's three-dimensional structure and enabling its reconstitution into new cathodes. The recycled cathodes exhibit electrochemical performance comparable to new commercial counterparts, demonstrating the effectiveness of the flash recycling process. Life cycle analysis shows that flash recycling offers significant environmental and economic benefits over traditional destructive methods, reducing energy and water consumption, greenhouse gas emissions, and operational costs. The flash recycling method is non-destructive, maintaining the cathode's bulk structure and allowing for the recovery of metals like lithium, cobalt, nickel, and manganese with high efficiency. The process involves flash Joule heating to induce carbothermal reduction, followed by magnetic separation to isolate ferromagnetic components. The non-ferromagnetic portion is then reprocessed for further recycling. The method is scalable and can be applied to various cathode chemistries, including LCO and NMC. The recycled cathodes show improved electrochemical performance, with high capacity retention and stability after multiple cycles. The flash recycling method also reduces metal impurities, such as Al and Cu, to levels below safety thresholds, ensuring the quality of the recycled materials. The process is energy-efficient, with significant reductions in water and energy consumption compared to traditional methods. Overall, flash recycling provides a sustainable and efficient solution for the recovery of cathode materials from spent LIBs, reducing environmental impact and enhancing resource efficiency.