Memory Effect of MgAl Layered Double Hydroxides Promotes LiNO3 Dissolution for Stable Lithium Metal Anode

LiNO3 is an effective additive for improving the performance of Li metal anodes. However, the practical application of LiNO3 is limited due to its poor solubility. Here, a novel electrolyte additive of MgAl layered double hydroxides (LDHs) with open interlayered anionic vacancies is proposed. The electropositive MgAl LDHs promote the spontaneous coordination of NO3- into anionic vacancies of LDH interlayers via memory effect, rehydrating to original NO3--MgAl LDHs structure and accelerating LiNO3 dissolution. The reconstructed NO3--MgAl LDHs play a crucial role as sustainable nitrate resources, preventing partial NO3- from participating in the Li+ solvent sheath to reduce the solvation binding energy. Moreover, MgAl LDHs absorb the anions due to electrostatic attraction, accounting for more dissociated Li+ and active Li+ migration in carbonate electrolytes. NO3- stored in MgAl LDHs is also preferentially reduced to form Li3N-rich solid electrolyte interphase (SEI), decreasing the activation energy barrier for Li+ transport and striving to form a uniform Li deposition. The cells assembled with MgAl LDHs and LiNO3 additives deliver high Coulombic efficiency, excellent rate capability, and high capacity retention. This strategy provides new insights into LiNO3-promotor design and excavates the potential of LDHs materials for Li metal batteries.

Automated summary

A novel electrolyte additive of MgAl layered double hydroxides (LDHs) is proposed to improve the solubility of LiNO3 and enhance the performance of Li metal anodes. MgAl LDHs promote the coordination of NO3- ions and absorb anions, leading to more dissociated Li+ ions and improved Li+ migration in carbonate electrolytes. The cells assembled with MgAl LDHs and LiNO3 additives demonstrate high Coulombic efficiency, excellent rate capability, and high capacity retention. This study provides new insights into LiNO3 promoter design and explores the potential of LDHs materials for Li metal batteries.