Selective extraction of lithium from brines has attracted significant interests with the rapid development of lithium battery industry. LiMn₂O₄ (LMO) is a typical lithium intercalation material with good redox activity and high theoretical adsorption capacity. However, the poor conductivity and stability of LMO lead to its performance deterioration. Here, LMO was in situ grown on graphene oxide flakes (LMO/GO) by pre-synthesis of Mn₃O₄ in the presence of GO followed by hydrothermal lithiation. Cyclic voltammetry and galvanic charge/discharge demonstrated the in situ synthesis of LMO on GO and enhanced the reversibility of the redox process and the rate performance of LMO. By adjusting the GO amount, the resultant LMO/GO electrode presented a high adsorption capacity and excellent selectivity for Li⁺ adsorption in capacitive deionization device. In contrast with pure LMO, the stability and adsorption capacity of LMO/GO were drastically improved with the capacity retention of 80% in 150 cycles. The effect of the other cations (K⁺, Na⁺, Mg²⁺, Ca²⁺) on Li⁺ adsorption was negligible, and the separation factor reached 47.8 at a Li/Mg molar ratio of 30. When applied for synthetic brine, the electrode held high Li⁺ adsorption amount of 720.2 μmol g⁻¹, demonstrating the feasibility of LMO/GO for Li⁺ extraction from brine.

Graphical Abstract

中文翻译：

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LiMn2O4 在氧化石墨烯上的原位生长，通过电容去离子有效提取锂

随着锂电池行业的快速发展，从卤水中选择性提取锂引起了人们的极大兴趣。LiMn ₂ O ₄ (LMO)是一种典型的嵌锂材料，具有良好的氧化还原活性和较高的理论吸附容量。然而，LMO较差的导电性和稳定性导致其性能下降。在这里，LMO 通过预合成 Mn ₃ O _{4在氧化石墨烯薄片 (LMO/GO) 上原位生长}在 GO 存在下进行水热锂化。循环伏安法和原电池充电/放电证明了LMO在GO上的原位合成，并增强了氧化还原过程的可逆性和LMO的倍率性能。通过调节GO的量，所得的LMO/GO电极在电容去离子装置中表现出高吸附容量和优异的Li ^{+吸附选择性。}与纯LMO相比，LMO/GO的稳定性和吸附容量显着提高，150次循环后容量保持率为80%。其他阳离子（K ⁺、Na ⁺、Mg ²⁺、Ca ²⁺）对Li ^+的影响吸附量可以忽略不计，在Li/Mg摩尔比为30时，分离因子达到47.8。当应用于合成盐水时，电极保持较高的Li ⁺吸附量，达到720.2 μmol g ^-1，证明了LMO/GO对Li的可行性⁺从盐水中提取。

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