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

Abstract

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 ─NH₂ 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 NH₂-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.