Thermo-managing and flame-retardant scaffolds suppressing dendritic growth and polysulfide shuttling toward high-safety lithium–sulfur batteries

Abstract Recently, safety issues associated with the practical application of lithium–sulfur (Li–S) batteries have attracted tremendous concern. Herein, a nonflammable 3D porous framework is constructed from functional boron nitride nanosheets (f-BNNSs) supported on a scaffold of continuous functional carbon nanotubes (f-CNTs) as a bifunctional host for Li–S batteries. The unique 3D porous structure with high thermal conductivity provides a well-distributed heat field with smooth and ultrafast heat-conduction channels during continuous battery operation even at a high temperature, thereby ensuring timely and effective heat transfer and avoiding the thermal runaway caused by accumulated heat and excessive local temperature. The incombustible f-BNNSs act as a physical flame-retardant barrier to prevent the occurrence and spread of combustion. In addition, the uniform electric field with low local current density inhibit the growth of Li dendrites, avoiding the excessive local temperature caused by the formation of an uneven thermal field. The abundant polar functional groups effectively suppress polysulfide shuttling, reducing the extra heat accumulation generated by severe electrode polarization. This work provides a “two-in-one” strategy for realizing high-safety batteries via a “prevention and post-treatment” method that combines thermal field regulation and flame retardancy, and thus promotes the commercial development of Li–S batteries.