Low-Temperature Lithium Metal Batteries Achieved by Synergistically Enhanced Screening Li Desolvation Kinetics.

Lithium metal anode is desired by high capacity and low potential toward higher energy density than commercial graphite anode. However, the low-temperature Li metal batteries suffer from dendrite formation and dead Li resulting from uneven Li behaviors of flux with huge desolvation/diffusion barriers, thus leading to short lifespan and safety concern. Herein, differing from electrolyte engineering, a strategy of delocalizing electrons with generating rich active sites to regulate Li desolvation/diffusion behaviors are demonstrated via decorating polar chemical groups on porous metal-organic frameworks (MOFs). As comprehensively indicated by theoretical simulations, electrochemical analysis, in situ spectroscopies, electron microscope, and time-of-flight secondary-ion mass spectrometry, the sieving kinetics of desolvation is not merely relied on pore size morphology but also significantly affected by the ─NH polar chemical groups, reducing energy barriers for realizing non-dendritic and smooth Li metal plating. Consequently, the optimal cells stabilize for long lifespan of 2000 h and higher average Coulombic efficiency, much better than the-state-of-art reports. Under a lower negative/positive ratio of 3.3, the full cells with NH-MIL-125 deliver a high capacity-retention of 97.0% at 0.33 C even under -20 °C, showing the great potential of this kind of polar groups on boosting Li desolvation kinetics at room- and low-temperatures.