P-Doped Cotton Stalk Carbon for High-Performance Lithium-Ion Batteries and Lithium-Sulfur Batteries

Biomass as a carbon material source is the characteristic of green chemistry. Herein, a series of hierarchical P-doped cotton stalk carbon materials (HPCSCMs) were prepared from cheap and abundant biowaste cotton stalk. These materials possess a surface area of 3463.14 m² g^-1 and hierarchical pores. As lithium-ion battery (LIB) anodes, the samples exhibit 1100 mAh g^-1 at 0.1 A g^-1 after 100 cycles and hold 419 mAh g^-1 at 1 A g^-1 after 1000 cycles, with nearly 100% capacity retention. After HPCSCMs are loaded with sulfur (S/HPCSCMs), the samples (S/HPCSCMs-2) deliver a discharge capacity of 413 mAh g^-1 at 0.1 A g^-1 after 100 cycles as lithium-sulfur (Li-S) battery cathodes. This excellent electrochemical performance can be attributed to P in carbon networks, which not only provides more active sites, but also improves electrical conductivity.