Lithium storage performance and optimal design of porous carbon materials with lettuce leaves

As a new energy material of environmental protection, biomass porous carbon material has been a research hotspot in recent years. In this paper, the porous carbon materials from lettuce leaves (LLs-temperature-proportional-activator) were prepared under different conditions, such as sintering temperature, the different activator, and the mass ratio of raw material and the activator, and the technological conditions were optimized through the discussion on their lithium storage performances. The results show that there are two broad and weak XRD peaks at 2θ=22°-26° and 2θ≈43° in each material, corresponding to the lattice plane (002) and (101), which indicates that the material is an amorphous carbon material with a certain degree of graphitization. In addition, the first discharge capacity of LLs-800-4R-K can reach 674.5 mAh/g. After 200 cycles, its discharge specific capacity can be maintained at 209.6 mAh /g, and the energy density is 146.8 Wh/kg. It illustrates that LLs-800-4R-K has good cycle performance and specific capacity. Thus, the optimum process conditions are as follows. The sintering temperature is at 800 ℃, KOH is used as activator, the mass ratio of raw material and the activator is 1:4.