The lithium metal batteries (LMBs) using Li metal as the anode are becoming one of the representatives of next-generation high-energy–density batteries. However, uneven deposition and stripping of Li usually cause capacity loss during cycling. To address these issues, NO 3 − intercalated LiAl layered double hydroxides (LiAl-LDHs) nanosheets were used as novel solid additives for conventional carbonate electrolytes. The abundant Li + transport pathways brought by LiAl-LDHs and the interlayer NO 3 − in LiAl-LDHs are beneficial to the uniform concentration distribution of Li + and high-quality solid electrolyte interface (SEI), thereby achieving stable deposition/stripping of Li. The assembled Li||Li symmetric cell was cycled stably for 500 h at a current density of 0.5 mA cm −2 . The Li||LFP(LiFePO 4 ) full cell had a capacity retention of 90 % after 800 cycles at 1C. Even at a high operating temperature of 50 °C, the Li||Li symmetric cells and Li||LFP full cells can still obtain steady charging-discharging performances.
Lithium extraction from salt lake brine is critical for satisfying the increasing demand of a variety of lithium products. We report lithium recovery from pre-synthesized LiAl-layered double hydroxides (LDHs) via a mild solution reaction. Lithium ions were released from solid LiAl-LDHs to obtain a lithium-bearing solution. The LiAl-LDHs phase was gradually transformed into a predominantly Al(OH)3phase with lithium recovery to the aqueous solution. The lithium recovery percentage and the concentration of the lithium-bearing solution were dependent on the crystallinity of LiAl-LDHs, the initial concentration of the LiAl-LDHs-1 slurry, the reaction temperature, and the reaction time. Under optimized conditions, the lithium recovery reached 86.2% and the Li+concentration in the filtrate is 141.6 mg/L. Interestingly, no aluminum ions were detected in the filtrate after solid–liquid separation with high crystallinity LiAl-LDHs, which indicated the complete separation of lithium and aluminum in the liquid and solid phases, respectively. The27Al NMR spectra of the solid products indicate that lithium recovery from the lattice vacancies of LiAl-LDHs affects the AlO6coordination in an octahedral configuration of the ordered Al(OH)3phase. The XPS O 1sspectra show that the Oadpeak intensity increased and the OLpeak intensity decreased with the increasing lithium recovery, which indicated that the Al-OH bond was gradually formed and the metal–oxygen–metal bond was broken.Keywords:lithium recovery;LiAl-LDHs;reaction-coupled separation technology;salt lake brine
Jinqiang Gao,Yuqing Su,Feng Dong,Mei Hong,Shihe Yang
Lithium extraction is of paramount importance for the emerging batteries. For salt lakes or recyclable lithium-containing materials, various metal ions are unavoidable, including Na + , K + , Ca 2+ and Mg 2+ . Lithium aluminum layered double hydroxides (LiAl-LDHs), as the most mature adsorbent, have been intensively studied on adsorption capacity and stability, but the cation adsorption selectivity is confusing and sometimes contradictory. To decipher the intrinsic cation selectivity of this nanosheets adsorbent, we track the mass fluctuation using operando quartz crystal microbalance with dissipation (QCM-D) method. First, we establish this effective monitoring strategy through accurately discriminating the adsorption-desorption behavior of interference-free LiAl-LDH/LiAlFe-LDH nanosheets. Then, by combining adsorption process of metal ions and density functional theory (DFT) calculations, we determine the intrinsic ion-selectivity sequence of Li + > Mg 2+ ≫ Na + ≈ K + ≈ Ca 2+ . For ions larger than Li + (0.76 Å), a well-crystallized structure hardly adsorbs Na + (1.02 Å), K + (1.38 Å), and Ca 2+ (1.00 Å) limited by the steric hinderance. Meantime, the dehydration energy consumption of hydrated ions determines the trend of Li + > Mg 2+ . Following, the SA-LiAl-LDH (composite binder-LDH adsorbent) directly corroborates that the misleading interfacial process result from sodium alginate binder adsorption. The work ends the confusion on the intrinsic properties of LiAl-LDHs and provides a clear insight for deciphering the myriad of ion adsorption selectivity.
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