Electrochemical Pre-delithiation of Li⁺ Intercalation Materials for Electrochemical Lithium Extraction

Electrochemical lithium extraction is considered a promising method to achieve lithium extraction from salt lake brine. This work investigated the pre-delithiation mechanism of LiMn2O4 (LMO) and LiNi1/3Co1/3Mn1/3O2 (LNCM). The Li+ pre-delithiation ratios and Li+ deintercalated kinetics were regulated by optimizing the pre-delithiation voltage of LMO and pre-delithiation current of LNCM. The lattice shrinkage and oxidation of Mn in LMO, and the lattice distortion and stepwise oxidation of Ni and Co in LNCM during pre-delithiation were identified. Moreover, the relationship between the pre-delithiation ratio and electrochemical lithium extraction capacity was correlated and optimized. The LMO pre-delithiated at 1.0 V achieved 72.4% pre-delithiation ratio and obtained a Li+ intercalation capacity of 2.35 mmol g–1, and the LNCM pre-delithiated at 1.5 mA achieved 75.7% pre-delithiation ratio and obtained a Li+ intercalation capacity of 1.21 mmol g–1. Furthermore, the lithium intercalation capacity of LMO-1.0 and LNCM-1.5 in Qarhan brine reached 4.31 and 4.41 mmol g–1, respectively. Eventually, the generalized strategies for pre-delithiating LMO and LNCM were proposed.