A space-confined carbonization strategy to prepare P-doped carbon nanosheets using expanded vermiculite as a template for high-performance lithium-ion battery anode

Heteroatom-doped porous carbon nanosheets have rapidly emerged as viable anode materials for lithium-ion batteries due to their high specific surface area, excellent electrical conductivity, and abundant active sites. Herein, phosphorus-doped carbon nanosheets (P-CNS) are synthesized via a space-confined carbonization strategy using phytic acid as carbon and phosphorus source and expanded vermiculite as a template. The obtained P-CNS have a unique sheet-like structure with a large surface area (∼746 m2/g), abundant hierarchical pore structure (the total pore volume of 0.609 cm3/g), and phosphorus atoms (the corresponding content of 2.25 %), which exists as P−O and P−C. P-CNS anode for lithium-ion batteries exhibits an excellent reversible capacity (1704 mAh/g at 0.05 A/g) and extraordinary cycling performance (capacity retention of 89.4 % at 5 A/g after 1000 cycles). The huge surface area and rich pore structure, which can provide transport paths and storage sites for lithium ions, are responsible for the exceptional performance. Furthermore, the phosphorus atoms not only introduce defects in P-CNS, but P−O and P−C can also increase the adsorption of lithium ions. This work provides a promising method to synthesize high-performance phosphorus-doped carbon nanosheets anode for lithium-ion batteries.