Battery recycling has emerged as a critical component of sustainable energy storage systems, driven by the increasing demand for electric vehicles and renewable energy integration. As the industry evolves, standardized terminology has become essential for clear communication among researchers, manufacturers, and recyclers. This article defines key terms in battery recycling, focusing on processes and materials without delving into technical or economic specifics.

Black mass refers to the intermediate product obtained after mechanical processing of spent lithium-ion batteries. It consists of a mixture of valuable metals, including lithium, cobalt, nickel, and manganese, along with carbonaceous materials from the anode. The production of black mass typically involves shredding and sieving battery cells to separate the electrode materials from other components. This powder-like substance serves as the feedstock for subsequent metallurgical processes. The composition of black mass varies depending on the original battery chemistry, with ratios of metals differing between lithium nickel manganese cobalt oxide (NMC), lithium cobalt oxide (LCO), and other cathode formulations. Proper handling of black mass is crucial as it may contain reactive materials and requires specific safety precautions during transportation and processing.

Cathode reclaim describes the process of recovering and reprocessing cathode materials from spent batteries for reuse in new battery production. Unlike complete material breakdown, cathode reclaim aims to preserve the original crystal structure of the cathode material when possible. This approach differs from full metal extraction as it seeks to maintain the functional integrity of the cathode material. The quality of reclaimed cathode material depends on the degradation state of the original battery and the efficiency of the separation processes. Successful cathode reclaim can reduce the energy intensity compared to producing entirely new cathode materials, though it requires careful control of impurities and structural defects.

Hydrometallurgical process refers to a recycling method that uses aqueous chemistry to extract metals from battery materials. This approach involves leaching metals into solution using acids or other reagents, followed by purification steps such as solvent extraction, precipitation, or electrowinning. The hydrometallurgical route offers selective recovery of individual metals and can achieve high purity levels suitable for battery-grade materials. Temperature, pH, and reagent concentration are carefully controlled parameters that influence the efficiency of metal extraction. The process generates liquid waste streams that require proper treatment before disposal or reuse. Compared to pyrometallurgical methods, hydrometallurgy typically operates at lower temperatures and can be more energy-efficient for certain battery chemistries.

Pyrometallurgical process involves high-temperature treatment of battery materials to recover valuable metals. In this approach, batteries or black mass undergo smelting in furnaces at temperatures exceeding 1000°C, where organic components burn off and metals separate into distinct phases. The process typically produces a mixed alloy containing cobalt, nickel, and copper, along with a slag phase containing lithium and aluminum. Subsequent refining steps separate the individual metals for reuse. Pyrometallurgy can handle entire battery packs without extensive pretreatment, but high energy requirements and emissions control present operational challenges. The method proves particularly effective for recovering base metals but may require additional steps for lithium recovery compared to hydrometallurgical routes.

Several supporting terms complete the battery recycling lexicon. Pre-treatment encompasses all operations before metal recovery, including discharging, dismantling, and mechanical separation. Mechanical separation refers to physical processes like crushing, sieving, and magnetic separation that prepare materials for further processing. Leaching describes the dissolution of metals from solid materials into liquid solutions, a fundamental step in hydrometallurgy. Electrowinning represents the electrochemical recovery of metals from solution, typically producing high-purity metal deposits. Slag denotes the silicate-based byproduct of pyrometallurgical operations that may contain recoverable lithium.

The battery recycling industry continues to develop specialized terminology as technologies advance. Terms like direct recycling describe emerging methods that aim to regenerate cathode materials with minimal processing, while urban mining refers to the concept of recovering materials from end-of-life products rather than virgin ores. Closed-loop recycling indicates systems where materials re-enter the same product cycle, contrasting with open-loop systems where materials may transition to different applications.

Understanding these terms provides a foundation for discussing battery recycling processes without confusion. The precise definitions help distinguish between different technological approaches and their respective advantages for various battery chemistries and formats. As recycling technologies evolve, the terminology will continue to expand and refine to accommodate new methods and materials in this rapidly developing field. Standardization of these terms facilitates clearer communication across research, industry, and policy sectors working toward more sustainable battery ecosystems.