Facile synthesis of phosphorus-doped carbon under tuned temperature with high lithium and sodium anodic performances

Abstract

Phytic acid derived carbons provide an excellent dual functionality for lithium- and sodium-ion batteries under tuned pyrolysis temperature. The acquired carbon at 800 °C is suitable to lithium-ion batteries due to its high surface area (1426.75 m2 g−1) and hierarchical porous structure. Tested against Li, it delivers a high capacity of 1787 mA h g−1 and coulombic efficiency of 82%. Another obtained carbon at 950 °C is suitable to sodium-ion batteries due to its large lattice spacing (0.4115 nm), defect density and phosphorus content (1.12%). Tested against Na, it delivers the initial specific capacity of 387 mA h g−1 with coulombic efficiency of 50.6%, and maintains a high reversible capacity of 300 mA h g−1 after 300 cycles at a current rate of 100 mA g−1. High energy density and power density are also acquired in lithium- and sodium-ion batteries. The effects of pyrolysis temperature on microstructure and electrochemical behaviours of carbons are discussed detailedly. It is proved that the carbons with tuned pyrolysis temperature behave differently due to a synergistic effect among the lattice spacing, graphitization degree, defect density, phosphorus concentration and porous structure.