Direct Recycling of Aged LiMn₂O₄ Cathode Materials used in Aqueous Lithium‐ion Batteries: Processes and Sensitivities

Aged LiMn 2 O 4 cathode materials were collected from aqueous electrolyte lithium‐ion batteries after long‐term cycling. The aged LiMn 2 O 4 cathode materials, which had variable states of charge, were recycled using two different “direct“ methods: solid‐state, and hydrothermal. X‐ray diffraction and electrochemical analysis revealed that the hydrothermal method yielded a recycled product with higher phase purity, electrochemical energy storage capacity. Additionally, the importance of the state of charge of the aged LiMn 2 O 4 on the recycled product varied depending on the methodology used. While the recycled products from the solid‐state method were sensitive to the state of charge of the aged LiMn 2 O 4 , the state of charge of the aged LiMn 2 O 4 doesn't have an obvious effect on the hydrothermally recycled product.