Highly Active Depleting Agent of Lithium Enabled High-Rate and Long-Life Lithium Metal Batteries

Abstract

Lithium metal is a highly potential anode material for developing high specific energy density battery systems, but the uncontrollable generation and growth of lithium dendrites upon plating/stripping reduces the reversible capacity of batteries and Coulombic efficiency and possibly leads to short circuit or even fire, all of which retard the commercial application of lithium metal batteries (LMBs). In this work, a modified separator with a thin layer of Li4Ti5O12 (LTO) inserted between two traditional polypropylene (PP) separators was presented to effectively eliminate the influence of lithium dendrites and improve the rate performance and lifetime of LMBs. Benefiting from the good wettability to the electrolyte, high conductivity of lithium ions, and quick depletion of lithium dendrites due to the insertion of lithium into the LTO lattice, LMBs with LTO-modified separator display excellent electrochemical performances, e.g., in the Li–Li cells, and an ultralong and stable operation over 1000 h at an areal current density of 0.5 mA/cm2 can be realized. More interestingly, in Li/LFP full cells, a high discharge capacity of 135 mAh/g at 1C with a lifetime over 600 cycles and 120 mAh/g at 5C with a lifetime over 300 cycles can be achieved. These inspiring results suggest a feasible route to achieve a safer, longer-life, and higher-rate LMB.