Inhibition of manganese ion migration and dissolution by selective ions sieving effect of MOF-based solid...

Lithium manganese oxide (LiMn₂O₄) is a promising cathode material for Li-ion batteries due to its abundant reserves and high discharge voltage. However, the dissolution and migration of transition metal Mn ions during the cycling process will cause a significant deterioration of capacity. In this study, a MOF-based quasi-solid electrolyte (UiO-QSE) is proposed to tackle this issue. The large specific surface area and open metal sites of UiO-QSE facilitate the adsorption of Mn ions, thereby inhibiting their migration. Furthermore, the disproportionation of Mn³⁺ on LiMn₂O₄ is suppressed by maintaining a highly concentrated Mn²⁺ layer around the cathode surface, thereby providing cathode protection in accordance with Le Chatelier's principle. The excellent inhibitory effect of UiO-QSE on the dissolution and migration of Mn ions is reflected in the fact that the prepared LiMn₂O₄|UiO-QSE|Li battery exhibits high discharge capacity (100.2 mAh·g^-1 after 100 cycles), which is much higher than LiMn₂O₄|LE|Li (78.1 mAh·g^-1), and a high capacity retention of 97.91 % after 50 cycles at a high-temperature of 45 °C. The Li|Li symmetrical cell exhibits an ultralong cycle life of more than 1300 h even at a high current density of 1 mA cm^-2 due to the uniform Li-ion transport channel and high Young's modulus in the UiO-QSE. This study is the first to employ the MOF-QSE strategy to inhibit the dissolution and migration of manganese during cycling, providing a new perspective on the development and enhancement of lithium-manganese-based batteries.