Application of transition metal boride nanosheet as sulfur host in high loading Li-S batteries

Two-dimensional (2D) metal boride material (MBene) has aroused concern recently. However, the research and application exploration for MBene materials with more exposure sites are seriously restricted due to lack of suitable preparation methods. Herein, a kind of composites of monolayer MBene nanosheets and carbon nanotube (mono-MBene/CNT) is prepared through ice template method for the first time and applicated as a novel cathode host in high-loading lithium-sulfur (Li-S) batteries. Benefiting from multifunctional advantages of mono-MBene/CNT cathode including anchoring lithium polysulfides (LiPS), multiple functional sites and fast lithium-ion transport, the cells with S@mono-MBene/CNT cathode exhibit superior long-term cycling performance over 1000 cycles. Most notably, even if the sulfur loading is up to 15.28 mg cm−2, the cells with S@mono-MBene/CNT cathode deliver an initial area capacity of 12.73 mAh cm−2 and the capacity can also maintain at 11.07 mAh cm−2 after 120 cycles (86.96 % capacity retention) with current density of 21.80 mA cm−2, which is approximately 3 times higher than the capacity of commercial lithium-ion batteries. This work not only provides a guiding role in preparing monolayer MBene material, but also exhibits the application prospect for MBene material in the fields of energy storage.