Low-cost, scalable integration of graphene with LiMn 2 O 4 for selective lithium extraction via hybrid capacitive deionization

Hybrid capacitive deionization (HCDI) is a promising strategy for selective lithium extraction from brines, yet scalable fabrication of high-performance electrodes remains challenging. Here, we report a ball milling strategy for the low-cost, scalable integration of graphene with LiMn ₂ O ₄ (LMO) for selective lithium extraction via HCDI. The ball milling process exfoliates graphite into graphene and reduces the LMO particle size, enabling their in situ integration. The ball milled graphene/LMO composite (BGL) features a continuous conductive network with uniformly dispersed LMO nanoparticles, which simultaneously promotes charge transport, enhances active site accessibility, and suppresses Mn dissolution, thereby improving cycling stability. Accordingly, the BGL electrode achieves a Li ⁺ adsorption capacity of 35.2 mg g ^− 1 and rate of 2.3 mg ^− 1 g ^− 1 min ^− 1 , with 97.4% capacity retention over 50 cycles. It also enables high-purity Li ⁺ recovery from simulated salt lake and actual low-grade brines. This ball milling approach allows scalable production of BGL, offering a practical route for industrial-grade HCDI electrode fabrication.