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基于锂离子电池充放电过程的可逆氧化还原反应原理,提出利用NiPO_4/LiNiPO_4电极对盐湖卤水进行锂镁分离的思路。运用同系线性规律对Me(Li,Na,K,Mg)-Ni-P-H_2O中NiPO_4,Ni_3(PO_4)_2,LiNiPO_4,Na NiPO_4,KNiPO_4,Mg_(0.5)NiPO_4的标准吉布斯自由能进行了估算。在热力学计算的基础上绘制了298.15 K时,Me(Li,Na,K,Mg)-Ni-P-H_2O系的φ-p H图,讨论了NiPO_4对盐湖卤水中主要金属离子(Li~+,Na~+,K~+,Mg~(2+))的选择性吸附行为。结果表明:水溶液中存在LiNiPO_4,Na NiPO_4,KNiPO_4的稳定区,还原电位(vs SHE)分别为0.2379,-0.0291,0.0209 V,不存在Mg_(0.5)NiPO_4的稳定区。在实际盐湖卤水(Mg/Li质量比为67)离子浓度条件下,NiPO_4/LiNiPO_4电极对仍具有良好的选择性提锂功能。而天然卤水的p H一般在7左右,表明此时无需添加酸或碱来调节卤水的p H,这与节能减排和环境保护的理念不谋而合,不断重复脱嵌锂过程即可从盐湖卤水中选择性提取锂。
Based on the principle of reversible redox reaction in the process of charge-discharge of lithium-ion batteries, the idea of using NiPO_4 / LiNiPO_4 electrode to separate lithium-magnesium brine from salt lake brine was proposed. The Gibbs free energy of NiPO_4, Ni_3 (PO_4) _2, LiNiPO_4, Na NiPO_4, KNiPO_4 and Mg_ (0.5) NiPO_4 in Me (Li, Na, K, Mg) -Ni-P-H_2O Estimated. The phi-p H diagrams of Me (Li, Na, K, Mg) -Ni-P-H 2 O systems were plotted on the basis of thermodynamic calculations at 298.15 K. The effects of NiPO 4 on the formation of the major metal ions (Li ~ , Na ~ +, K ~ +, Mg ~ (2+)). The results show that the stable region of LiNiPO_4, Na NiPO_4 and KNiPO_4 exists in the aqueous solution with the reduction potential of 0.2379, -0.0291 and 0.0209 V, respectively. There is no stable region of Mg_ (0.5) NiPO_4. In the actual salt lake brine (Mg / Li mass ratio of 67) ion concentration conditions, NiPO_4 / LiNiPO_4 electrode pairs still have a good selective lithium extraction function. The natural brine pH is generally around 7, indicating that at this time without the need to add acid or alkali to adjust the pH of brine, which is consistent with the concept of energy conservation and environmental protection, and constantly repeat the process of de-intercalating lithium from Selective extraction of lithium from salt lake brine.