Hard-carbon hybrid Li-ion/metal anode enabled by preferred mesoporous uniform lithium growth mechanism

Abstract

To achieve high energy density in lithium batteries, the construction of lithium-ion/metal hybrid anodes is a promising strategy. In particular, because of the anisotropy of graphite, hybrid anode formed by graphite/Li metal has low transport kinetics and is easy to causes the growth of lithium dendrites and accumulation of dead Li, which seriously affects the cycle life of batteries and even causes safety problems. Here, by comparing graphite with two types of hard carbon, it was found that hybrid anode formed by hard carbon and lithium metal, possessing more disordered mesoporous structure and lithophilic groups, presents better performance. Results indicate that the mesoporous structure provides abundant active site and storage space for dead lithium. With the synergistic effect of this structure and lithophilic functional groups (–COOH), the reversibility of hard carbon/lithium metal hybrid anode is maintained, promoting uniform deposition of lithium metal and alleviating formation of lithium dendrites. The hybrid anode maintains a 99.5% Coulombic efficiency (CE) after 260 cycles at a specific capacity of 500 mAh/g. This work provides new insights into the hybrid anodes formed by carbon-based materials and lithium metal with high specific energy and fast charging ability.