CNT threaded porous carbon nitride nanoflakes as bifunctional hosts for lithium sulfide cathode

Abstract Lithium sulfide (Li2S) is regarded as a promising cathode material for lithium ion batteries since it can be well paired with lithium–free anodes. However, the low electronic conductivity of Li2S and the shuttle effect of lithium polysulfides are the two biggest obstacles for commercial applications of Li2S cathode. Herein, a bifunctional host with high electronic conductivity and high adsorption of lithium polysulfides, CNT threaded porous carbon nitride nanoflakes, is designed and prepared for Li2S cathode. Ultrafine Li2S particles are infiltrated into the bifunctional host to form a three-dimensional Li2S/porous carbon nitride/carbon nanotube composite (3D Li2S/p–C3N4/CNT) by facile liquid infiltration and evaporation. The as–prepared 3D Li2S/p–C3N4/CNT exhibits a high initial discharge capacity of 997.5 mAh g−1 at 0.2 A g–1, superior rate capability of 432.3 mAh g−1 at 2.0 A g–1 over 600 cycles and good cycling stability. The excellent electrochemical performance of 3D Li2S/p–C3N4/CNT can be attributed to the high conductivity network of CNT and ultrafine Li2S, and the strong polar adsorption of porous carbon nitride nanoflakes.