Simple synthesis of Ni/high porosity biomass carbon composites with enhanced electrochemical performance of lithium–sulfur battery

Biomass charcoal with high porosity has been widely used in the field of energy storage materials. In this work, high-porosity biochar(HPBC) was prepared by a carbonization-activation method using a high-efficiency pore-forming agent KOH. The prepared HPBC was a porous material dominated by micropores and mesopores with a specific surface area of 2500 m2/g, and the pore volume of 1.18 cm3/g. Then, nickel nanoparticles were uniformly grown on the surface of HPBC via the electroless nickel plating to form HPBC/Ni. And finally, sublimed sulfur was introduced to prepare HPBC/Ni/S composites as cathode material for lithium sulfur battery. In this structure, HPBC can served as an efficient sulfur storage material, and nickel can be used to catalyze the reaction to enhance the reaction kinetics, while the two materials can also synergistically perform physicochemical adsorption of lithium polysulfide. The results showed that the prepared HPBC/Ni/S composite electrode has a first discharge capacity of 907.3 mAh/g at a rate of 0.5C. After 200 cycles, it still maintains 610.6 mAh/g, and the single-turn attenuation rate is only 0.16%.