Tuning Surface Energy of Pristine Separator with γ-AlO(OH) Nanocapsules for Inhibiting Lithium Polysulfide Shuttle and Lithium Dendrite Growth

The severe shuttling of dissolved lithium polysulfides (LiPSs) (Li₂S_x, 4 ≤ x ≤ 8) and the generation of lithium dendrites upon cycling have hampered the safety and performance of lithium-sulfur batteries (LSB). Herein, we report the strategy of tuning the surface energy of the pristine separator with γ-AlO(OH) nanocapsules to address the aforementioned problems. The enhanced surface energy from 26.62 to 63.64 mJ m^-2 yields multiple benefits, including impeding the migrating polysulfides by chemically binding them with γ-AlO(OH) nanocapsules, enhancing the lithium-ion migration through the separator by promoting hydrophilicity in the separator and mitigating the generation of lithium dendrites by a uniform distribution of Li⁺ on top of lithium metal via interaction with γ-AlO(OH) nanocapsules. Live discharging of the H-cell demonstrated that the LiPS mitigation can be curtailed by using γ-AlO(OH) nanocapsules modified separator (BNC). Moreover, the BNC separator’s thermally insulating properties render the Li-S battery stable behavior while cycling at an even temperature of 75 °C. The spray coating technology used for coating γ-AlO(OH) nanocapsules on top of pristine separator offers a scalable solution for commercializing such modified separators.