HIGHLIGHTS Aqueous processed NCM523 cathodes show performance comparable with the NMP processed one The spent NCM523 compound was separated from other cathode components in water The spent NCM523 was successfully relithiated, restored and showed performance comparable with the pristine This provides a potential path toward green and sustainable battery manufacturing

Rapid adoption of lithium‐ion batteries for electronics and electric vehicles requires cost‐effective and efficient recycling of battery components especially the valuable cathode active materials. The direct recycling method transforms end‐of‐life (EOL) cathode materials into battery grade materials with minimal energy consumption and least environmental disruption. In direct recycling, the relithiation step to restore the lithium stoichiometry of the cathode materials is critical. In this work, a novel electrochemical relithiation approach in an aqueous electrolyte followed by a heat treatment for recycling cathode materials in EOL lithium‐ion batteries is demonstrated and analyzed. Using LiCoO2 as an example, it is shown that the recycled LiCoO2 materials show equivalent crystal structure, morphology, and electrochemical performance to the commercial LiCoO2.

A new sodium–sulfur (Na–S) flow battery utilizing molten sodium metal and flowable sulfur‐based suspension as electrodes is demonstrated and analyzed for the first time. Unlike the conventional flow battery and the high‐temperature Na–S battery, the proposed flow battery system decouples the energy and power thermal management by operating at different temperatures for the storage tank (near room temperature) and the power stack (100–150 °C). The new Na–S flow battery offers several advantages such as easy preparation and integration of the electrode, low energy efficiency loss due to temperature maintenance, great tolerance of the volume change of the metal anode, and efficient utilization of sulfur. The Na–S flow battery has an estimated system cost in the range of $50–100 kWh−1 which is very competitive for grid‐scale energy storage applications.

The prevalence of electric vehicles (EVs) globally could generate a huge number of spent Li-ion batteries (LIBs) as they reach their end of life. It is expected that by 2030, 11 million metric tons of EOL LIBs will be generated cumulatively, with annual waste flows of EV batteries reaching 34,000 t by 2040. Recycling spent LIBs in a sustainable and effective manner is a matter of utmost importance. Conventional recycling strategies such as pyrometallurgy and hydrometallurgy decompose the crystal structures of value-added electrode materials to element levels, presenting fatal drawbacks in high greenhouse gas emissions, cost, and energy consumption. The burgeoning direct recycling processes provide viable options to rejuvenate LIB compounds without chemical change, thus retaining their original composition as well as the embedded energy. Relithiation and defect restoration are the critical steps for electrode regeneration, which determine the performance of recovered material. Here, the authors provide a detailed discussion and analysis on different regeneration methods for LIB electrodes based on their degradation mechanisms. The advancements of direct recycling among other recycling technologies are highlighted through discussions of its process benefits. Physical pretreatments including deactivation, disassembly, and black mass separation are introduced. Perspectives toward scaled applications of direct recycling are also demonstrated on the basis of developing trends of future LIBs.

Determination of the lithium ion content in cathode materials, which is currently performed by coupled plasma-mass spectrometry (ICP-MS), involves tedious procedures and error-prone preparation. This work introduces a new methodology to quickly determine the lithium content in spent cathode materials (LiNi x Mn y Co z O 2 , x+y+z=1, NMC) using a thermalgravimetric analysis, which bypasses the use of ICP-MS and significantly reduces the cost and time required for determining the lithium content. Based on this new method, a new approach is developed to identify spent cathode materials suitable for direct relithiation recycling. Finally, these new methods have been applied to investigate the effectiveness of direct electrochemical-relithiation on recycling the spent cathodes, and provide insights for future development of direct battery materials recycling.