Preparation of B-doped porous carbon nanosheets and their lithium storage performance
Anode materials are one of the critical factors affecting the electrochemical performance of lithium-ion batteries(LIBs).Pore structure modulation and heteroatom doping effectively improve the electrochemical performance of anode materials.In this paper,coal-based carbon nanosheets(CS)were prepared by using lignite as a precursor chemical oxidation method.Then B-doped porous carbon nanosheets(BPCS)were obtained using boron oxide(B2O3)as an additive.The microstructures of CS and BCPS were characterized by scanning electron microscopy(SEM),transmission electron microscope(TEM),X-ray diffraction(XRD),Raman spectroscopy(Raman),nitrogen adsorption-desorption and X-ray photoelectron spectroscopy(XPS),and the electrochemical properties of CS and BPCS as anode materials for LIBs were investigated.The results showed that B2O3 had triple functions of template,pore-making and doping.When the dosage of B2O3 was 0.5g,BPCS-0.5 exhibited a three-dimensional porous structure with a specific surface area of 1216.20m2/g,a total pore volume of 1.027cm3/g,and content of B atom of 4.20%.The porous structure of BPCS-0.5 provided sufficient space and channels for ion storage and transport,and the introduction of B element increased the surface chemical activity of BPCS,which enhanced the lithium storage performance.When BPCS-0.5 as anode material of LIBs,the first reversible capacity reached 826mA·h/g at a current density of 0.05A/g and the reversible capacity still reached 143mA·h/g at a high current density of 5A/g,and the capacity retention rate of 500 cycles was 172%,indicating that the anode materials had high lithium storage capacity and excellent cycle life.
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