Suppression of lithium dendrite by aramid nanofibrous aerogel separator

With the pursuit of a high-specific-energy battery, lithium metal battery (LMB) that using lithium (Li) metal anode has attracted great attention in recent years. To achieve a stable, long-term cycle of LMB, various battery components, including electrolytes, separators and composite lithium anode, have been explored. The separator, although it does not involve in any cell reaction directly, plays a critical role in cell performance. In this work, we report a novel-type separator, a free-standing aerogel film that possesses high specific surface area (SSA), which realizes uniform lithium deposition and inhibits the parasitic reaction that usually occurs between the liquid electrolyte solvents and Li-metal during the charge/discharge cycling in the Li-symmetric cell. Even in the Li-metal battery with Li4Ti5O12 or LiFePO4 as the counter electrode, the aramid nanofibrous aerogel film shows much better performance than that of the glass fiber separator, which has 25 times lower SSA. The surface-assisted partial desolvation effect makes the Li+ easier to obtain electrons and be reduced to Li-metal. This result provides a strategy for stabilizing the Li-metal anode using a functional separator that could regulate the structure of Li+-solvates.