Synthesis And Properties Of Carbon-based Nanomaterials And Application For Energy Storage

Lithium ion battery and electrocatalytic water splitting are two important ways for electrochemical energy storage and conversion in the field of clean energy.Graphite as anode materials in lithium ion battery have been commercialized,but it can not meet the needs of the rapidly developing science and technology,due to its relatively low theoretical specific capacity.On the other hand,the use of carbon-based nanostructured materials instead of precious metals and transitional metals in catalytic water-splitting system provides a promising way to clean,recyclable and sustainanle energy.In order to meet the demand of the clean energy,one of the keys is to design high-capacity lithium ion battery and high-performance water-splitting electrocatalyst to improve current technology in energy storage and conversion.Based on the literature reviews on the performance of current carbon-based anodes in lithium ion battery and water-splitting electrocatalyst,we aim to develop new strategies to prepare carbon-based electrode materials for use in energy storage and conversion.The main results of the thesis include the followings:1.The uniform carbon nano-balls were obtained via low-temperature solid state reaction with CaC2 and PCl5 as raw materials in Teflon-lined stainless steel autoclave.Electrochemical tests show the obtained carbon nano-balls after calcination exhibit excellent capacity as lithium ion battery anodes,much higher than the commercial graphite anodes.Moreover,the carbon nano-ball anodes show excellent rate performance and long-term cycling stability.The discharge specific capacity can be still maintained at 550 mAh g-1 with neglible loss after 230 cycles at the current density of 1 A/g,which is superior to traditional graphite material.2.P-doped C nanosheets on nickel foam were prepared by using CaC2 and PCls as raw materials via a low-temperature vapor deposition method.Electrochemical tests show that NF@P-Doped C exhibits enhanced electrochemical performance,more than three times higher than that of NF and much improved performance relative to other published carbon-based electrodes.More interestingly,NF@P-Doped C exhibits an efficient bifunctional electrode for overall water splitting,which is rare for a carbon-based electrocataly that usually has a poor HER performance in alkaline solution.NF@P-Doped C delivers an overpotential of 340 mV and 227 mV OER and HER,respectively at a current density of 10 mA/cm2 in 1M KOH.Even in low concentration of 0.1 M KOH solution,it shows excellent electrocatalytic properties of OER with an overpotential of 340 mV at current density of 10 mA/cm2.The excellent eletrocatalytic performance of NF@P-Doped C is likely due to its unique structures,in which the P-doped carbon nanosheet uniformly grew on the surface of nickel foam and effectively reduce the overpotential resulting from the binder and contact resistance.3.P-dope carbon was also grown on graphene-coated Ni foam by using a similar procedure.The obtained NF@G@P-Doped C electrode shows excellent electrocatalytic performance for oxygen evolution reaction(OER).The electrocatalytic activity of NF@G@P-Doped C is better than that of NF@P-Doped C,and the durability also gets improved.For oxygen evolution reaction(OER),it just needs an overpotential of 330 mV at a current density of 30 mA/cm2.Even in 0.1 M KOH solution it shows excellent electrocatalytic properties with an overpotential of 370 mV at current density of 10 mA/cm2.