钛酸锂纳米阵列电极材料的电导性和电容性的研究
发布时间：2018-08-20 09:07
【摘要】：近年来,超级电容器作为一种具有较高的能量密度和较长循环使用寿命的新型电化学能量转换和储能设备被广泛关注。超级电容器由电解质、隔膜以及两个电极组成。电极材料是超级电容器中最重要的组成部分。一般来说,电极材料的形貌、结构及电化学性能在超级电容器的研究中起着关键作用。尖晶石钛酸锂(Li_4Ti_5O_(12))电极材料因其具有零应变性、良好的可逆性、优异的循环性能、结构稳定性好、高安全性能、价格低廉、环境友好等优点被作为超级电容器电极材料,具有良好的开发应用前景。然而,Li_4Ti_5O_(12)本体的电导率十分低,只有10~(-1)3Scm~(-1)-,严重的阻碍了它的发展与应用。离子掺杂、电极材料的纳米化、表面修饰是三种提高Li_4Ti_5O_(12)的电导率最有效的方法。本文以提高Li_4Ti_5O_(12)电极材料的导电性,优化Li_4Ti_5O_(12)电极材料的电化学性能为目标,制备了具有纳米管阵列结构的钛酸锂(Li_4Ti_5O_(12)NTA)电极材料,然后通过离子掺杂、石墨烯(RGO)、碳包覆、氮化钛(TiN)表面修饰等手段对Li_4Ti_5O_(12)NTA进行改性,制备了氮化钛-钛酸锂纳米管阵列(TiN-Li_4Ti_5O_(12)NTA)、石墨烯-碳包覆钛酸锂(RGO/C-Li_4Ti_5O_(12) NTA)、氮化钛-镁掺杂钛酸锂电极材料(TiN-Li_(4-x)Mg_xTi_5O_(12) NTA)三种电极材料。研究了以上电极材料的形貌、结构及其电化学性能。此外,还研究了三种电极材料在超级电容器中的应用。本论文的研究工作主要包括以下几个方面。(1)TiN-Li_4Ti_5O_(12)NTA电极材料的制备及其电化学性能的研究。TiN-Li_4Ti_5O_(12)NTA电极材料通过锂化、高温煅烧、氮化方式合成。通过阳极氧化的方法在Ti片表面形成Ti02纳米管阵列(TiO2 NTA)。然后TiO2 NTA与LiOH发生锂化反应,经过高温煅烧形成Li_4Ti_5O_(12)NTA。在Li_4Ti_5O_(12)NTA表面上包覆一层Ti02溶胶,在700℃下氮化1 h,形成TiN-Li_4Ti_5O_(12)NTA。扫描结果显示,TiN纳米颗粒包覆在Li_4Ti_5O_(12)NTA的表面,使形成的TiN-Li_4Ti_5O_(12)NTA的表面变得更为粗糙。TiN-Li_4Ti_5O_(12) NTA与 N-Li_4Ti_5O_(12)NTA 的电导率分别为 39.06 S cm~(-1) 和 14.01 S cm~(-1),表明 TiN-Li_4Ti_5O_(12) NTA具有较高的电导性。在0.5M的Li2S04电解质溶液中,在-0.4～0.8V的电势窗口下进行电化学性能测试。当电流密度为O.5Ag~(-1)时,TiN-Li_4Ti_5O_(12)NTA电极材料的比电容为143.83 F g~(-1),在3 Ag~(-1)的电流密度下进行1000次恒电流充放电后,比电容保持率为82.41%。TiN-Li_4Ti_5O_(12) NTA电极材料提供较大的比表面积,能够有效地提高TiN-Li_4Ti_5O_(12)NTA电极材料的电容性能。基于TiN-Li_4Ti_5O_(12)NTA电极材料和聚乙烯醇-硫酸锂(PVA-Li2SO4)凝胶电解质制备的全固态对称超级电容器,其电压为2.4V。当电流密度为0.5Ag~(-1)时,TiN-Li_4Ti_5O_(12) NTA超级电容器的比能量为32.36 Wh kg~(-1)。体积为10 mm×22 mm×0.5 mm的器件可以点亮工作电压为2V的LED灯,说明TiN-Li_4Ti_5O_(12) NTA电极材料可以作为超级电容器材料。(2)RGO/C-Li_4Ti_5O_(12)NTA电极材料的制备及其电化学性能的研究本章主要以分散有RGO的PVA为碳源,在600℃碳化3h,合成了 C-Li_4Ti_5O_(12)/RGO NTA电极材料。利用RGO的高导电性来提高Li_4Ti_5O_(12) NTA的电导性,以提升其电容性能。扫描结果显示,含有石墨烯片的碳层均匀的分布在Li_4Ti_5O_(12)NTA的表面。在0.5 M的Li2SO4中,-0.6～0.6V的电势窗下,电流密度为0.5Ag~(-1)时,C-Li_4Ti_5O_(12)/RGONTA电极材料的比电容为210.76 F g~(-1)。在3 A g~(-1)的电流密度下进行1000个恒电流充放电后,C-Li_4Ti_5O_(12)/RGONTA的比电容保持率为89.99%,说明RGO包覆在的表面Li_4Ti_5O_(12)NTA使它的电化学性能有了明显的提高。RGO/C-Li_4Ti5012 NTA电极材料和PVA-Li2S04凝胶电解质制备成全固态对称超级电容器储能器件,其测试电压为2.4V。电流密度从0.5Ag~(-1)增加到10Ag~(-1),功率密度从0.6 kW kg~(-1)升高到12 kW kg~(-1),能量密度从39.98 Wh kg~(-1)降低到12.36 Wh kg~(-1),体积为10 mm × 20 mm× 0.5 mm的器件可以点亮工作电压为2 V的LED灯,说明RGO/C-Li_4Ti_5O_(12) NTA电极材料可以作为有效的超级电容器材料。(3)TiN-Li_(4-x)Mg_xTi_5O_(12)NTA电极材料的制备及其电化学性能的研究本章采用以硝酸镁(Mg(NO_3)_2)为镁源对Li_4Ti_5O_(12) NTA进行Mg2+掺杂,合成了Li_(4-x)Mg_xTi_5O_(12) NTA,然后将TiO2溶胶包覆在Li_(4-x)Mg_xTi_5O_(12) NTA表面,在700℃下氮化1h,形成TiN-Li_(4-x)Mg_xTi_5O_(12)NTA。扫描结果显示Mg2+掺杂后,Li_4Ti_5O_(12)NTA的形貌没有发生明显的改变,仍呈纳米管阵列结构。氮化后Li_(4-x)Mg_xTi_5O_(12)NTA表面覆盖了一层细小的颗粒。EDS检测结果显示,TiN-Li_(4-x)Mg_xTi_5O_(12)NTA电极材料的EDS谱图中检测到了 Ti、O、Mg以及N。在0.5 M的Li2S04为电解质溶液中,-0.4～0.8 V的电势窗下,进行电化学恒电流充放电测试。当电流密度为0.5 A g~(-1)时,TiN-Li_(4-x)Mg_xTi_5O_(12) NTA电极材料的比电容为224.58 F g~(-1)。在3 A~(-1)的电流密度下进行1000次循环充放电后,TiN-Li_(4-x)Mg_xTi_5O_(12) NTA的电容保持率为89.53%,说明Mg2+掺杂和TiN有效地改善了电极材料的电化学性能。基于TiN-Li_(4-x)Mg_xTi_5O_(12)NTA电极材料和聚乙烯醇-硫酸锂(PVA-Li2SO4)凝胶电解质制备的全固态对称超级电容器,其测试电压窗口为2.4 V。当电流密度为0.5 A g~(-1)时,TiN-Li_(4-x)Mg_xTi_5O_(12) NTA 电容器的比能量 42.61 Wh kg~(-1)。体积为 30 mm× 10 mm×0.5 mm的器件可以点亮工作电压为2 V的LED灯,说明TiN-Li_(4-x)Mg_xTi_5O_(12)NTA电极材料表现出优异的储能性能。
[Abstract]:In recent years, as a new type of electrochemical energy conversion and storage equipment with high energy density and long cycle life, supercapacitor is widely concerned. It consists of electrolyte, diaphragm and two electrodes. Electrode material is the most important part of supercapacitor. Spinel lithium titanate (Li_4Ti_5O_ (12)) electrode materials have been used as electrode materials for supercapacitors because of their zero strain, good reversibility, excellent cycling performance, good structural stability, high safety performance, low cost and environmental friendliness. However, the conductivity of Li_4Ti_5O_ (12) bulk is very low, only 10-1_ 3Scm_ (1) -, which seriously hinders its development and application. Ion doping, nanocrystallization of electrode materials and surface modification are the three most effective methods to improve the conductivity of Li_4Ti_5O_ (12). In this paper, the Li_4Ti_5O_ (12) electrode materials are studied. To optimize the electrochemical performance of Li_4Ti_5O_ (12) electrode materials, lithium titanate (Li_4Ti_5O_ (12) NTA) electrode materials with nanotube arrays were prepared. Then Li_4Ti_5O_ (12) NTA was modified by ion doping, graphene (RGO), carbon coating and surface modification of titanium nitride (TiN). Nanotube arrays (TiN-Li_4Ti_5O_ (12) NTA), graphene-carbon coated lithium titanate (RGO/C-Li_4Ti_5O_ (12) NTA), titanium nitride-magnesium doped lithium titanate electrode materials (TiN-Li_ (4-x) Mg_xTi_5O_ (12) NTA) were used as electrode materials. The morphology, structure and electrochemical properties of the above electrode materials were studied. The research work of this paper mainly includes the following aspects: (1) Preparation of TiN-Li_4Ti_5O_ (12) NTA electrode material and its electrochemical properties. TiN-Li_4Ti_5O_ (12) NTA electrode material is synthesized by lithium, high temperature calcination and nitridation. Ti02 nanotube array (TiO2) is formed on the surface of Ti sheet by anodic oxidation method. TiN-Li_4Ti_5O_ (12) NTA was prepared by lithium reaction between titanium dioxide NTA and LiOH. TiN-Li_4Ti_5O_ (12) NTA was coated on the surface of Li_4Ti_5O_ (12) NTA and nitrided at 700 C for 1 h to form TiN-Li_4Ti_5O_ (12) NTA. Scanning results showed that TiN nanoparticles were coated on the surface of Li_4Ti_5O_ (12) NTA and formed TiN-Li_4Ti_5O_ (12) NTA. The conductivities of TiN-Li_4Ti_5O_ (12) NTA and N-Li_4Ti_5O_ (12) NTA were 39.06 S cm ~(-1) and 14.01 S cm ~(-1), respectively, indicating that TiN-Li_4Ti_5O_ (12) NTA had higher conductivity. The electrochemical properties of TiN-Li_4Ti_5O_ (12) NTA were tested in Li2S04 electrolyte solution of 0.5 M at a potential window of - 0.4 to 0.8 V. (1) The specific capacitance of TiN-Li_4Ti_5O_ (12) NTA electrode material is 143.83 F g~(-1), and the specific capacitance of TiN-Li_4Ti_5O_ (12) NTA electrode material is 82.41% after 1000 times of constant current charging and discharging at the current density of 3Ag~(-1). TiN-Li_4Ti_5O_ (12) NTA electrode material provides a large specific surface area, which can effectively improve the capacitance performance of TiN-Li_4Ti_5O_ (12) NTA electrode material. All-solid-state symmetrical supercapacitors based on TiN-Li_4Ti_5O_ (12) NTA electrode materials and polyvinyl alcohol-lithium sulfate (PVA-Li2SO_4) gel electrolytes have a voltage of 2.4V. When the current density is 0.5Ag~(-1), the specific energy of TiN-Li_4Ti_5O_ (12) NTA supercapacitors is 32.36 Wh kg~(-1). Devices with a volume of 10 mm *22 mm *0.5 mm can be brightened. The working voltage of LED lamp is 2V, indicating that TiN-Li_4Ti_5O_ (12) NTA electrode material can be used as supercapacitor material. (2) Preparation of RGO/C-Li_4Ti_5O_ (12) NTA electrode material and its electrochemical properties. In this chapter, the C-Li_4Ti_5O_ (12)/RGO NTA electrode material was synthesized by carbonization of PVA with RGO at 600 for 3h. Scanning results show that the carbon layer containing graphene sheet is uniformly distributed on the surface of Li_4Ti_5O_ (12) NTA. In Li_2SO_4 of 0.5 M, - 0.6-0.6 V potential window, the specific capacitance of C-Li_4Ti_5O_ (12)/RGONTA electrode material is 210. 76 F g~(-1). The specific capacitance of C-Li_4Ti_5O_ (12)/RGO NTA was maintained at 89.99% after 1000 constant current charges and discharges at 3 A g~(-1) current density, indicating that the electrochemical performance of RGO coated surface Li_4Ti_5O_ (12) NTA was significantly improved. RGO/C-Li_4Ti5012 NTA electrode material and PVA-Li2S04 gel electrolyte were prepared into solid state. A state-symmetrical supercapacitor energy storage device has a test voltage of 2.4 V. The current density increases from 0.5 Ag~(-1) to 10 Ag~(-1), the power density increases from 0.6 kW kg~(-1) to 12 kW kg~(-1), the energy density decreases from 39.98 Wh kg~(-1) to 12.36 Wh kg~(-1), and the device with a volume of 10 mm (3) Preparation of TiN-Li_ (4-x) Mg_xTi_5O_ (12) NTA electrode material and its electrochemical properties. In this chapter, Li_ (4-x) Mg_xTi_5O_ (12) NTA was synthesized by Mg2+ doping of Li_4Ti_5O_ (12) NTA with Mg (NO_3) _2 as the Mg source. TiN-Li_ (4-x) Mg_xTi_5O_ (12) NTA was formed by sol-coated Li_ (4-x) Mg_ (4-x) Mg_xTi_5O_ (12) NTA after nitriding for 1 h at 700 C. Scanning results showed that the morphology of Li_4Ti_5O_ (12) NTA did not change significantly after doping with Mg2 +, but remained as a nanotube array structure. The results show that the EDS spectra of TiN-Li_ (4-x) M g_xTi_5O_ (12) NTA electrode materials show that the specific capacitance of TiN-Li_ (4-x) M g_xTi_5O_ (12) NTA electrode materials is 224.4 when the current density is 0.5 A g~(-1) and the specific capacitance of TiN-Li_ (4-x) M g_xTi_5O_ (12) NTA electrode materials is 0.5 M in Li2S04 electrolyte solution and - 0.4-0.8 V potential window. 58 F g~(-1). After 1000 cycles of charging and discharging at the current density of 3A~(-1), the capacitance retention of TiN-Li_ (4-x) Mg_xTi_5O_ (12) NTA was 89.53%, indicating that Mg2+ doping and TiN effectively improved the electrochemical performance of electrode materials. Based on TiN-Li_ (4-x) Mg_xTi_5O_ (12) NTA electrode materials and polyvinyl alcohol-lithium sulfate (PVA-Li2SO4) gel electrolysis The specific energy of TiN-Li_ (4-x) Mg_xTi_5O_ (12) NTA capacitor is 42.61 Wh kg~(-1). A device with a volume of 30 mm 10 mm 0.5 mm can turn on the LED lamp with a working voltage of 2 V, indicating that TiN-Li_ (4-x) Mg_xTi_5O_ (12) NTA electrode can be turned on when the current density is 0.5 A g~(-1). The materials exhibit excellent energy storage properties.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ131.11;TM53
本文编号：2193103
[Abstract]:In recent years, as a new type of electrochemical energy conversion and storage equipment with high energy density and long cycle life, supercapacitor is widely concerned. It consists of electrolyte, diaphragm and two electrodes. Electrode material is the most important part of supercapacitor. Spinel lithium titanate (Li_4Ti_5O_ (12)) electrode materials have been used as electrode materials for supercapacitors because of their zero strain, good reversibility, excellent cycling performance, good structural stability, high safety performance, low cost and environmental friendliness. However, the conductivity of Li_4Ti_5O_ (12) bulk is very low, only 10-1_ 3Scm_ (1) -, which seriously hinders its development and application. Ion doping, nanocrystallization of electrode materials and surface modification are the three most effective methods to improve the conductivity of Li_4Ti_5O_ (12). In this paper, the Li_4Ti_5O_ (12) electrode materials are studied. To optimize the electrochemical performance of Li_4Ti_5O_ (12) electrode materials, lithium titanate (Li_4Ti_5O_ (12) NTA) electrode materials with nanotube arrays were prepared. Then Li_4Ti_5O_ (12) NTA was modified by ion doping, graphene (RGO), carbon coating and surface modification of titanium nitride (TiN). Nanotube arrays (TiN-Li_4Ti_5O_ (12) NTA), graphene-carbon coated lithium titanate (RGO/C-Li_4Ti_5O_ (12) NTA), titanium nitride-magnesium doped lithium titanate electrode materials (TiN-Li_ (4-x) Mg_xTi_5O_ (12) NTA) were used as electrode materials. The morphology, structure and electrochemical properties of the above electrode materials were studied. The research work of this paper mainly includes the following aspects: (1) Preparation of TiN-Li_4Ti_5O_ (12) NTA electrode material and its electrochemical properties. TiN-Li_4Ti_5O_ (12) NTA electrode material is synthesized by lithium, high temperature calcination and nitridation. Ti02 nanotube array (TiO2) is formed on the surface of Ti sheet by anodic oxidation method. TiN-Li_4Ti_5O_ (12) NTA was prepared by lithium reaction between titanium dioxide NTA and LiOH. TiN-Li_4Ti_5O_ (12) NTA was coated on the surface of Li_4Ti_5O_ (12) NTA and nitrided at 700 C for 1 h to form TiN-Li_4Ti_5O_ (12) NTA. Scanning results showed that TiN nanoparticles were coated on the surface of Li_4Ti_5O_ (12) NTA and formed TiN-Li_4Ti_5O_ (12) NTA. The conductivities of TiN-Li_4Ti_5O_ (12) NTA and N-Li_4Ti_5O_ (12) NTA were 39.06 S cm ~(-1) and 14.01 S cm ~(-1), respectively, indicating that TiN-Li_4Ti_5O_ (12) NTA had higher conductivity. The electrochemical properties of TiN-Li_4Ti_5O_ (12) NTA were tested in Li2S04 electrolyte solution of 0.5 M at a potential window of - 0.4 to 0.8 V. (1) The specific capacitance of TiN-Li_4Ti_5O_ (12) NTA electrode material is 143.83 F g~(-1), and the specific capacitance of TiN-Li_4Ti_5O_ (12) NTA electrode material is 82.41% after 1000 times of constant current charging and discharging at the current density of 3Ag~(-1). TiN-Li_4Ti_5O_ (12) NTA electrode material provides a large specific surface area, which can effectively improve the capacitance performance of TiN-Li_4Ti_5O_ (12) NTA electrode material. All-solid-state symmetrical supercapacitors based on TiN-Li_4Ti_5O_ (12) NTA electrode materials and polyvinyl alcohol-lithium sulfate (PVA-Li2SO_4) gel electrolytes have a voltage of 2.4V. When the current density is 0.5Ag~(-1), the specific energy of TiN-Li_4Ti_5O_ (12) NTA supercapacitors is 32.36 Wh kg~(-1). Devices with a volume of 10 mm *22 mm *0.5 mm can be brightened. The working voltage of LED lamp is 2V, indicating that TiN-Li_4Ti_5O_ (12) NTA electrode material can be used as supercapacitor material. (2) Preparation of RGO/C-Li_4Ti_5O_ (12) NTA electrode material and its electrochemical properties. In this chapter, the C-Li_4Ti_5O_ (12)/RGO NTA electrode material was synthesized by carbonization of PVA with RGO at 600 for 3h. Scanning results show that the carbon layer containing graphene sheet is uniformly distributed on the surface of Li_4Ti_5O_ (12) NTA. In Li_2SO_4 of 0.5 M, - 0.6-0.6 V potential window, the specific capacitance of C-Li_4Ti_5O_ (12)/RGONTA electrode material is 210. 76 F g~(-1). The specific capacitance of C-Li_4Ti_5O_ (12)/RGO NTA was maintained at 89.99% after 1000 constant current charges and discharges at 3 A g~(-1) current density, indicating that the electrochemical performance of RGO coated surface Li_4Ti_5O_ (12) NTA was significantly improved. RGO/C-Li_4Ti5012 NTA electrode material and PVA-Li2S04 gel electrolyte were prepared into solid state. A state-symmetrical supercapacitor energy storage device has a test voltage of 2.4 V. The current density increases from 0.5 Ag~(-1) to 10 Ag~(-1), the power density increases from 0.6 kW kg~(-1) to 12 kW kg~(-1), the energy density decreases from 39.98 Wh kg~(-1) to 12.36 Wh kg~(-1), and the device with a volume of 10 mm (3) Preparation of TiN-Li_ (4-x) Mg_xTi_5O_ (12) NTA electrode material and its electrochemical properties. In this chapter, Li_ (4-x) Mg_xTi_5O_ (12) NTA was synthesized by Mg2+ doping of Li_4Ti_5O_ (12) NTA with Mg (NO_3) _2 as the Mg source. TiN-Li_ (4-x) Mg_xTi_5O_ (12) NTA was formed by sol-coated Li_ (4-x) Mg_ (4-x) Mg_xTi_5O_ (12) NTA after nitriding for 1 h at 700 C. Scanning results showed that the morphology of Li_4Ti_5O_ (12) NTA did not change significantly after doping with Mg2 +, but remained as a nanotube array structure. The results show that the EDS spectra of TiN-Li_ (4-x) M g_xTi_5O_ (12) NTA electrode materials show that the specific capacitance of TiN-Li_ (4-x) M g_xTi_5O_ (12) NTA electrode materials is 224.4 when the current density is 0.5 A g~(-1) and the specific capacitance of TiN-Li_ (4-x) M g_xTi_5O_ (12) NTA electrode materials is 0.5 M in Li2S04 electrolyte solution and - 0.4-0.8 V potential window. 58 F g~(-1). After 1000 cycles of charging and discharging at the current density of 3A~(-1), the capacitance retention of TiN-Li_ (4-x) Mg_xTi_5O_ (12) NTA was 89.53%, indicating that Mg2+ doping and TiN effectively improved the electrochemical performance of electrode materials. Based on TiN-Li_ (4-x) Mg_xTi_5O_ (12) NTA electrode materials and polyvinyl alcohol-lithium sulfate (PVA-Li2SO4) gel electrolysis The specific energy of TiN-Li_ (4-x) Mg_xTi_5O_ (12) NTA capacitor is 42.61 Wh kg~(-1). A device with a volume of 30 mm 10 mm 0.5 mm can turn on the LED lamp with a working voltage of 2 V, indicating that TiN-Li_ (4-x) Mg_xTi_5O_ (12) NTA electrode can be turned on when the current density is 0.5 A g~(-1). The materials exhibit excellent energy storage properties.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ131.11;TM53
【参考文献】
相关期刊论文 前1条
1 张熊;孙现众;马衍伟;;高比能超级电容器的研究进展[J];中国科学:化学;2014年07期
相关博士学位论文 前3条
1 方巍;锂离子电池负极钛酸锂复合材料的制备与性能研究[D];哈尔滨工业大学;2013年
2 孟繁慧;基于新型纳米结构超级电容器材料的研究[D];山东大学;2013年
3 唐西胜;超级电容器储能应用于分布式发电系统的能量管理及稳定性研究[D];中国科学院研究生院（电工研究所）;2006年
相关硕士学位论文 前4条
1 王恩峰;超级电容器储能系统的充放电研究[D];南华大学;2015年
2 吴春;超级电容器用新型多孔碳材料的制备及其电化学性能研究[D];湘潭大学;2014年
3 董彬彬;超级电容器用Li_4Ti_5O_(12)/C电极材料的研究[D];北京化工大学;2014年
4 郭鑫;高倍率Li_4Ti_5O_(12)负极材料的制备及碳包覆研究[D];合肥工业大学;2014年
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