State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, Qinghai 810008, China.
ACS Appl Mater Interfaces. 2023 Jun 21;15(24):29586-29596. doi: 10.1021/acsami.3c04682. Epub 2023 Jun 11.
Salt lake brine has become a promising lithium resource, but it remains challenging to separate Li ions from the coexisting ions. We designed a membrane electrode having conductive and hydrophilic bifunctionality based on the HTiO ion sieve (HTO). Reduced graphene oxide (RGO) was combined with the ion sieve to improve electrical conductivity, and tannic acid (TA) was polymerized on the surface of ion sieve to enhance hydrophilicity. These bifunctional modification at the microscopic level improved the electrochemical performance of the electrode and facilitated ion migration and adsorption. Poly(vinyl alcohol) (PVA) was used as a binder to further intensify the macroscopic hydrophilicity of the HTO/RGO-TA electrode. Lithium adsorption capacity of the modified electrode in 2 h reached 25.2 mg g, more than double that of HTO (12.0 mg g). The modified electrode showed excellent selectivity for Na/Li and Mg/Li separation and good cycling stability. The adsorption mechanism follows ion exchange, which involves H/Li exchange and Li-O bond formation in the [H] layer and [HTi] layer of HTO.
盐湖卤水已成为一种很有前途的锂资源，但从共存离子中分离锂离子仍然具有挑战性。我们设计了一种基于 HTiO 分子筛（HTO）的具有导电和亲水性双功能的膜电极。还原氧化石墨烯（RGO）与分子筛结合以提高电导率，单宁酸（TA）在分子筛表面聚合以增强亲水性。这些微观水平上的双功能修饰提高了电极的电化学性能，促进了离子迁移和吸附。聚乙烯醇（PVA）用作粘合剂，进一步增强了 HTO/RGO-TA 电极的宏观亲水性。改性电极在 2 小时内的吸附容量达到 25.2mg/g，是 HTO（12.0mg/g）的两倍多。改性电极对 Na/Li 和 Mg/Li 的分离具有优异的选择性和良好的循环稳定性。吸附机制遵循离子交换，涉及 HTO 中 [H]层和 [HTi]层中的 H/Li 交换和 Li-O 键形成。
