Green closed-loop recycling process for all elements in spent LiMn2O4 cathode materials--颗粒学报PARTICUOLOGY

Qinglong Sun^a, Natnael Ghebretatios^a, Zhidong Chang^a *, Wei Wang^b *, Benard Amakanji Otota^a, Bin Dong^a, Jialong Li^a, Yaqi Wang^a, Leiying Zhang^a, Zhiyi Chen^a

a School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing, 100083, China
b State Key Laboratory of Biochemical Engineering-Separation Technology and Energy Chemistry Group, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, China

10.1016/j.partic.2026.03.017

Volume 114, July 2026, Pages 10-24

Received 11 January 2026, Revised 5 March 2026, Accepted 6 March 2026, Available online 30 March 2026, Version of Record 10 April 2026.

E-mail: zdchang@ustb.edu.cn; weiwang@ipe.ac.cn; dongbin@ustb.edu.cn

Highlights

• By combining NH₄Cl roasting with ammonia leaching process, s-LMO achieved closed-loop recovery.

• Overall Li recovery rate exceeded 96%, achieving 99% selective precipitation of Mn.

• No impurity cations were introduced in the whole process.

• Battery-grade Li₂CO₃ and Mn₃O₄ recovered were used to regenerate LMO.

• The regenerated LMO exhibited great electrochemical performances.

Abstract

With the impending surge in retired lithium-ion batteries, developing efficient strategies for recovering valuable elements has attracted significant attention. This study presents an innovative closed-loop recycling method that integrates NH₄Cl reductive roasting with a selective ammonia leaching system to achieve the complete recovery and regeneration of lithium and manganese from spent LiMn₂O₄ cathodes. The reaction mechanism was elucidated using XRD, SEM-EDS, and XPS demonstrating that Mn⁴⁺/Mn³⁺ in the LiMn₂O₄ spinel structure is simultaneously reduced and chlorinated by NH₄⁺ from molten ammonium salts. This synergistic process efficiently converts the cathode material into water-soluble LiCl and (NH₄)₂MnCl₄. Notably, residual nitrogen is stored and recycled as NH₄⁺, with no impurity cations introduced during roasting. Under optimized roasting conditions (350 °C, 15 min, w(s-LMO)/w(NH₄Cl) = 1:2.5), the chlorination extent of manganese reached 88%, with the residual fraction stabilized as Mn₃O₄, while the lithium conversion efficiency approached 96%. Subsequent leaching in an NH₃·H₂O–H₂O system enabled the nearly complete separation of Li and Mn, yielding battery-grade Li₂CO₃. The incorporation of 2 % H₂O₂ as an oxidizing agent facilitated the selective precipitation of over 99 % of the manganese in the form of spherical nano-crystalline Mn₃O₄, while the lithium leaching efficiency remained virtually quantitative. The overall recovery rate for lithium reached 96%, while that for manganese approached 100%. Thermodynamic analysis and comprehensive characterization reveal the underlying mechanisms governing this selective manganese precipitation. Finally, the regenerated LiMn₂O₄ cathode material synthesized via the closed-loop process exhibited excellent structural integrity and electrochemical performance, confirming the viability and sustainability of the proposed methodology.

Graphical abstract

Keywords

Spent LiMn₂O₄ cathode material; Reductive chlorination; Ammoniacal leaching; Li/Mn separation; Full-element closed-loop recovery; Cathode material regeneration

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