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Lithium Manganate Wrapped with Ion-Selective Graphene Coatings for Thermally Assisted Lithium Extraction from Simulated Seawater
Energy & Fuels ( IF 5.2 ) Pub Date : 2023-09-07 , DOI: 10.1021/acs.energyfuels.3c02323
Yanxi Yu 1 , Zixun Yu 1 , Leo Lai 1 , Fangzhou Liu 1 , Zhi Zheng 1 , Liuyue Cao 1 , Yuanyuan Yao 1 , Dong Suk Han 2 , Li Wei 1 , Yuan Chen 1
Affiliation  

Lithium (Li) is a critical element for various energy storage devices. Extracting Li from the ocean by electrochemical ion pumping using lithium manganate (LMO) could solve the potential Li shortages. In particular, a thermally assisted electrochemical Li+ extraction process using low-grade heat can speed up extraction and reduce energy consumption. However, LMO suffers from fast extraction capacity fading and insufficient selectivity for Li+ over Na+. Here, we show that the performance of LMO can be significantly improved by wrapping LMO with ion-selective reduced graphene oxide (rGO) coatings. The rGO coatings were assembled uniformly and controllably on LMO particles via a poly(diallyldimethylammonium) chloride interfacial binder. At the optimum mass ratio of 0.125 wt %, the rGO-coated LMO demonstrates a higher capacity retention of 75.1% than uncoated LMO over 50 charge/discharge cycles. When paired with a nickel hexacyanoferrate electrode for Li+ extraction from simulated seawater with a high Na+/Li+ molar ratio of 20 000 at 60 °C, rGO-coated LMO shows much less capacity loss of 23.13% and yields a higher Li purity of 65.49% than uncoated LMO. The improved performance can be attributed to the Donnan effect of rGO nanosheets in attracting cations from low Li concentration simulated seawater on electrode surfaces and the size exclusion effect by restricting the mass transfer of large ions. Less cointercalation of competing Na+ helps to ease the Jahn–Teller effect of LMO, resulting in enhanced crystalline structure stability. The thermally assisted Li extraction process has the potential to be further improved with innovative electrode material designs for practical applications.

中文翻译:

包裹有离子选择性石墨烯涂层的锰酸锂用于从模拟海水中热辅助提取锂

锂(Li)是各种储能设备的关键元素。使用锰酸锂(LMO)通过电化学离子泵从海洋中提取锂可以解决潜在的锂短缺问题。特别是,使用低品位热量的热辅助电化学Li +提取过程可以加快提取速度并降低能耗。然而,LMO 存在萃取能力快速衰减以及对 Li +相对于 Na +的选择性不足的问题。在这里,我们表明,通过用离子选择性还原氧化石墨烯(rGO)涂层包裹 LMO 可以显着提高 LMO 的性能。rGO涂层通过聚(二烯丙基二甲基氯化铵)界面粘合剂均匀且可控地组装在LMO颗粒上。在最佳质量比为 0.125 wt% 时,rGO 涂覆的 LMO 在 50 次充电/放电循环中表现出比未涂覆的 LMO 更高的 75.1% 的容量保持率。当与六氰基铁酸镍电极配合使用,在 60 °C下从 Na + /Li +摩尔比高达 20 000 的模拟海水中提取 Li +时,rGO 涂层的 LMO 显示出更少的容量损失(23.13%),并产生更高的 Li 纯度比未包衣的 LMO 提高了 65.49%。性能的提高可归因于rGO纳米片在电极表面吸引低锂浓度模拟海水中的阳离子的唐南效应以及通过限制大离子的传质而产生的尺寸排阻效应。竞争性 Na +的较少共嵌入有助于缓解 LMO 的 Jahn-Teller 效应,从而增强晶体结构稳定性。通过针对实际应用的创新电极材料设计,热辅助锂提取工艺有可能进一步改进。
更新日期:2023-09-07
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