Imbedding Li2CO3 in Li-nafion film to protect Li anode from unexpected dendrites growth

•The Li-Nafion/Li2CO3 film was designed and prepared successfully for the first time.•The presence of Li2CO3 endows the composite film more channels for Li+ migration.•The Li-S batteries using Li-Nafion/Li2CO3 film protected Li anode presents outstanding rate and cycling performance. The lithium-sulfur (Li-S) battery is considered as an appealing choice for the next-generation secondary battery due to its high theoretical energy density and low cost. However, the safety concerns and poor cycling performance caused by lithium dendrites seriously restrict its commercialization. A composite protective film with high lithium ionic conductivity has exhibited excellent inhibiting effect on the formation of lithium dendrites. Herein, Li-Nafion/Li2CO3 (LNL) composite film is developed to achieve a stable Li anode in Li-S batteries by redistributing Li+ flux. The Li-S batteries with LNL-5 film show an improved remaining discharge capacity of 730 mAh g−1 at 0.1 C after 100 cycles and rate performance of 425.4 mAh g−1 at 2 C. This work provides a rational design to suppress the formation of lithium dendrite for the stable Li anode in Li-S batteries.