The paper presents a solvent- and water-free flash Joule heating (FJH) method combined with magnetic separation to restore fresh cathodes from waste cathodes, followed by solid-state relithiation. This process, called flash recycling, is effective in recovering high yields of battery metals (~98%) and preserving the intact core structures of the cathodes. The resynthesized cathodes show comparable electrochemical performance to new commercial counterparts. Life cycle analysis highlights that flash recycling has higher environmental and economic benefits over traditional destructive recycling processes, reducing energy and water consumption, and lowering greenhouse gas emissions. The method is scalable and can be integrated into industrial systems for spent lithium-ion battery recycling.The paper presents a solvent- and water-free flash Joule heating (FJH) method combined with magnetic separation to restore fresh cathodes from waste cathodes, followed by solid-state relithiation. This process, called flash recycling, is effective in recovering high yields of battery metals (~98%) and preserving the intact core structures of the cathodes. The resynthesized cathodes show comparable electrochemical performance to new commercial counterparts. Life cycle analysis highlights that flash recycling has higher environmental and economic benefits over traditional destructive recycling processes, reducing energy and water consumption, and lowering greenhouse gas emissions. The method is scalable and can be integrated into industrial systems for spent lithium-ion battery recycling.