Dow Centre for Sustainable Engineering Innovation, School of Chemical Engineering, The University of Queensland, St. Lucia, Brisbane, QLD 4072, Australia.
Queensland Micro and Nanotechnology Centre, Griffith University, Nathan, QLD 4011, Australia.
Environ Sci Technol. 2024 Feb 27;58(8):3997-4007. doi: 10.1021/acs.est.3c09111. Epub 2024 Feb 17.
The electrochemical extraction of lithium (Li) from aqueous sources using electrochemical means is a promising direct Li extraction technology. However, to this date, most electrochemical Li extraction studies are confined to Li-rich brine, neglecting the practical and existing Li-lean resources, with their overall extraction behaviors currently not fully understood. More still, the effect of elevated sodium (Na) concentrations typically found in most Li-lean water sources on Li extraction is unclear. Hence, in this work, we first understand the electrochemical Li extraction behaviors from ultradilute solutions using spinel lithium manganese oxide as the model electrode. We discovered that Li extraction depends highly on the Li concentration and cell operation current density. Then, we switched our focus on low Li to Na ratio solutions, revealing that Na can dominate the electrostatic screening layer, reducing Li ion concentration. Based on these understandings, we rationally employed pulsed electrochemical operation to restructure the electrode surface and distribute the surface-adsorbed species, which efficiently achieves a high Li selectivity even in extremely low initial Li/Na concentrations of up to 1:20,000.
使用电化学方法从水溶液中电化学提取锂（Li）是一种很有前途的直接 Li 提取技术。然而，迄今为止，大多数电化学 Li 提取研究都局限于富锂卤水，而忽略了实际存在的贫锂资源，其整体提取行为目前尚未完全了解。更重要的是，大多数贫锂水源中通常存在的升高的钠离子（Na）浓度对 Li 提取的影响尚不清楚。因此，在这项工作中，我们首先使用尖晶石锂锰氧化物作为模型电极来理解从超低浓度溶液中电化学提取 Li 的行为。我们发现 Li 的提取高度依赖于 Li 浓度和电池操作电流密度。然后，我们将注意力转向低 Li 与 Na 比的溶液，揭示了 Na 可以主导静电屏蔽层，降低锂离子浓度。基于这些认识，我们合理地采用脉冲电化学操作来重构电极表面并分布表面吸附物种，即使在初始 Li/Na 浓度低至 1:20000 时，也能有效地实现高 Li 选择性。
