posted on 2024-02-17, 14:13authored byKaige Sun, Mike Tebyetekerwa, Xiangkang Zeng, Zhuyuan Wang, Timothy T. Duignan, Xiwang Zhang
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.