Kaixiong Xiang

Hierarchical porous LiFePO4/carbon composite electrodes for lithium-ion batteries

Hierarchical porous LiFePO4/C composite has been successfully synthesised via evaporative self-assembly induced by vegetable proteins. The morphologies and structures are investigated by X-ray diffractometer, scanning electron microscope and transmission electron microscope. Hierarchical porous LiFePO4/C composite presents the connected hierarchical porous structure and nano-carbon network embedded in connected hierarchical pores. LiFePO4/C composite with 5 wt% vegetable proteins (LFP-5C) delivers a higher capacity of 166.8 mA h g−1 than LiFePO4/C composite with 8 wt% vegetable protein (LFP-8C) (161.4 mA h g−1) at 0.1 C rate. However, at a high rate of 30 C, LFP-8C exhibits a little higher discharge capacity of 148.6 mA h g−1and capacity retention of 97.3% after 100 cycles than LFP-5C (145.6 mA h g−1, 96.8%). The hierarchical porous LiFePO4/C composite is a promising material for practical application in lithium-ion battery.

Porous carbons derived from tea-seed shells and their improved electrochemical performance in lithium-ion batteries and supercapacitors

Abstract Porous carbons derived from tea seed shells were fabricated through hydrothermal activation and high-temperature activation. The microstructure was investigated via X-ray diffraction, Raman spectrometer, scanning and electron microscopy techniques. The activated carbons show high specific surface areas and developed porosity, and reveal excellent electrochemical performance, especially for the TSSCB samples. When the carbon material TSSCB was applied for lithium-ion batteries, it delivered superior specific charge capacity of 598 mAh g−1 at 0∙1C, and showed an impressive rate capability of 440 mAh g−1 at 1C, and maintained high capacity retention of 82∙9% even after 500 cycles. Moreover, when the carbon material TSSCB was utilized in supercapacitor, it also exhibited high specific capacitance of 305∙7 F g−1 at the current density of 1 A g−1 and the capacitance retention ratio of 98∙6% after 10,000 cycles, indicating remarkable cycling stability. Porous carbons derived from tea seed shells are a potential energy storage material.

Preparation and lithium storage performance of silicon and carbon microrods by chemical vapor co-deposition

Silicon/carbon microrods are co-deposited on copper substrate and graphite spheres surface using dimethyl dichlorosilance as carbon and silicon precursor. The obtained composites are characterized by X-ray diffraction and scanning electron microscopy. The experimental results show that silicon/carbon microrods deposited on the copper substrate, whose diameter is about 500 nm, are accumulated into sisallike morphology, those deposited on the graphite spheres surface form hedgehog-like feature, whose diameter is about 200 nm and whose top is like cauliflower. When current density of 50 mA/g is applied, charge capacity of silicon/carbon microrods is 1492 mA h/g (deposited on copper substrate) and 693 mA h/g (deposited on the graphite spheres surface). Moreover, silicon/carbon microrods deposited on the graphite spehres and copper substrate respectively deliver the capacity of 592, 985 mA h/g, and display no capacity decay at all after the 20 cycles, when cycled under current density of 500 mA/g.