SiO作为锂离子电池负极材料的改性研究
发布时间：2019-01-30 07:58
【摘要】：硅由于在地壳中含量高，理论处理容量高达4200mAh/g,放电电压低而且安全性能优越成为锂离子电池负极材料的研究热点。但是，硅在深度脱嵌锂时体积效应大，易与导电介质集流体失去电接触导致的循环性能差、首次库伦效率低而且硅材料本身低导电率等限制了其在锂离子电池中商业化应用。改善硅基材料循环性能，缓冲其在循环过程中的体积膨胀并提高其导电性能成为硅基材料改性的主要方向。 本文主要以PAN（聚丙烯腈）为碳源通过不同的方法来制备SiO/CNx复合材料来作为锂离子电池的负极材料，此外，通过改变粘结剂来涂片研究粘结剂对复合材料电化学性能的影响。运用X射线衍射测试(XRD)、拉曼光谱(Raman)、傅里叶红外变换光谱(FT-IR)、X射线电子能谱(XPS)、扫描电子显微镜(SEM)了解复合材料的结构以及形貌特征，从这方面的改变来探讨材料改性的效果。用复合材料作为锂离子电池负极材料的电化学性能分别通过恒电流充放电、循环伏安(CV)、交流阻抗(EIS)的测试，了解复合材料的电化学性能。 以PAN为碳源，采用溶胶凝胶法与SiO混合，(质量比:PAN:SiO=3:7),在氩气下高温煅烧使PAN裂解后得到SiO/CNx复合材料，研究了温度对复合材料性能的影响。用PVDF作粘结剂，，当热处理温度为500°C时，得到的SiO/CNx复合材料性能最佳，首次放电容量为2009.3mAh/g，首次库伦效率为64.8%，经过50周循环后仍有360mAh/g的容量保留，相对于SiO经过10周仅剩100mAh/g有很大的提高。用海藻酸钠代替PVDF作粘结剂，当热处理温度为500°C时，电池的循环性能最好，首次放电容量为为2131.3mAh/g，首次库伦效率为71.8%，经过50周循环后仍有646.5mAh/g的容量保留，相对于使用PVDF作粘结剂，可逆容量有较大的提高。 同样以PAN为碳源，改用球磨法将SiO和PAN进行混合，然后高温热处理使得PAN裂解得到SiO/CNx复合材料，球磨法相对于溶胶凝胶法来说更能保证PAN和SiO的充分混合以及PAN的利用率。当热处理温度为500°C时，首次放电容量为1180.3mAh/g，首次库伦效率为65.9%，经过50周循环后可逆容量仍保持在490mAh/g左右。用海藻酸钠代替PVDF作粘结剂，当热处理温度为500°C时，电池的循环性能最好，首次放电容量为为1396.7mAh/g，首次库伦效率为72.4%，经过50周循环后仍有580.9mAh/g的容量保留，相对于使用PVDF作粘结剂，可逆容量有较大的提高，但电池的容量衰减较为严重，需要进一步改善来提高循环稳定性以及可逆容量。 通过“直接涂膜法”合成无需粘结剂的SiO/CNx复合材料电极。由于购买的SiO是微米级的，先通过球磨将微米级的SiO颗粒粒径减小到微纳米级别，命名为“milled SiO”。然后将“milled SiO”与PAN在DMF溶液中均匀混合，直至形成浆状物，将浆状物直接涂布在铜箔集流体上，然后在真空中80°C干燥，再将极片在Ar保护的管式炉中进行热处理，得到无需粘结剂的SiO/CNx复合材料电极。由于在热处理过程中，PAN裂解形成含氮的碳网包覆在“milled SiO”的表面，使得材料的导电性能和循环性能都有很大的提高。当热处理温度为500°C时，复合材料首次放电容量为2733.7mAh/g，首次库伦效率为74.9%，经过100次循环后容量仍有927.8mAh/g，相对于SiO有很大的改善。
[Abstract]:Because of the high content of silicon in the earth's crust, the theoretical treatment capacity is up to 4200mAh/ g, the discharge voltage is low and the safety performance is superior to that of the negative electrode material of the lithium ion battery. however, that bulk effect of the silicon in the deep deintercalation of the lithium is large, the cycle performance due to the loss of electrical contact with the conductive medium current collector is poor, the first coulomb efficiency is low, and the low conductivity of the silicon material itself and the like limit the commercial application of the silicon material in the lithium ion battery. improve the cycle performance of the silicon-based material, and buffer the volume expansion of the silicon-based material and improve the conductivity of the silicon-based material to be the main direction of the modification of the silicon-based material. The paper mainly uses PAN (PAN) as the carbon source to prepare the SiO/ CNx composite material as the negative electrode material of the lithium ion battery. In addition, the effect of the adhesive on the electrochemical performance of the composite material is studied by changing the adhesive. In this paper, X-ray diffraction (XRD), Raman spectroscopy (Raman), Fourier transform spectroscopy (FT-IR), X-ray electron spectroscopy (XPS), scanning electron microscope (SEM) were used to understand the structure and morphology of the composite, and the effect of material modification was discussed from the change in this aspect. The electrochemical performance of the negative electrode material of Li-ion battery was measured by constant current charging and discharging, cyclic voltammetry (CV) and AC impedance (EIS). The performance of the composite material was studied by using a sol-gel method and a sol-gel method (mass ratio: PAN: SiO = 3: 7). The results show that when the heat treatment temperature is 500 掳 C, the performance of the obtained SiO/ CNx composite material is the best, the first discharge capacity is 2009. 3mAh/ g, the first coulomb efficiency is 64. 8%, and the capacity of 360mAh/ g is reserved after the 50-week cycle, and only 100mAh/ g is left with respect to the SiO after 10 weeks. The results show that the initial discharge capacity of the battery is 2131. 3mAh/ g, the first discharge capacity is 2131. 3mAh/ g, the first discharge capacity is 71.8%, and the capacity of 646. 5mAh/ g is retained after the 50-week cycle, compared with the use of PVDF The binder and the reversible capacity are large. In the same way, the PAN is used as a carbon source, and the SiO and the PAN are mixed by a ball milling method, and then the high-temperature heat treatment is carried out so that the PAN is cracked to obtain the SiO/ CNx composite material, and the ball milling method is more capable of ensuring the sufficient mixing of the PAN and the SiO and the PA for the sol-gel method. N utilization. When the heat treatment temperature is 500 掳 C, the first discharge capacity is 1180. 3mAh/ g, the first coulomb efficiency is 65. 9%, and the reversible capacity after 50 cycles is still maintained at 490mA When the heat treatment temperature is 500 掳 C, the cycle performance of the battery is the best, the first discharge capacity is 1396. 7mAh/ g, the first discharge capacity is 72.4%, and the capacity of 580. 9mAh/ g is reserved after the 50-week cycle, relative to the use of PVD F is a binder, and the reversible capacity is greatly improved, but the capacity attenuation of the battery is more serious, and further improvement is needed to improve the cycle stability. and the reversible capacity, and the SiO/ CN without the binder is synthesized by the 鈥渄irect coating method鈥
本文编号：2417923
[Abstract]:Because of the high content of silicon in the earth's crust, the theoretical treatment capacity is up to 4200mAh/ g, the discharge voltage is low and the safety performance is superior to that of the negative electrode material of the lithium ion battery. however, that bulk effect of the silicon in the deep deintercalation of the lithium is large, the cycle performance due to the loss of electrical contact with the conductive medium current collector is poor, the first coulomb efficiency is low, and the low conductivity of the silicon material itself and the like limit the commercial application of the silicon material in the lithium ion battery. improve the cycle performance of the silicon-based material, and buffer the volume expansion of the silicon-based material and improve the conductivity of the silicon-based material to be the main direction of the modification of the silicon-based material. The paper mainly uses PAN (PAN) as the carbon source to prepare the SiO/ CNx composite material as the negative electrode material of the lithium ion battery. In addition, the effect of the adhesive on the electrochemical performance of the composite material is studied by changing the adhesive. In this paper, X-ray diffraction (XRD), Raman spectroscopy (Raman), Fourier transform spectroscopy (FT-IR), X-ray electron spectroscopy (XPS), scanning electron microscope (SEM) were used to understand the structure and morphology of the composite, and the effect of material modification was discussed from the change in this aspect. The electrochemical performance of the negative electrode material of Li-ion battery was measured by constant current charging and discharging, cyclic voltammetry (CV) and AC impedance (EIS). The performance of the composite material was studied by using a sol-gel method and a sol-gel method (mass ratio: PAN: SiO = 3: 7). The results show that when the heat treatment temperature is 500 掳 C, the performance of the obtained SiO/ CNx composite material is the best, the first discharge capacity is 2009. 3mAh/ g, the first coulomb efficiency is 64. 8%, and the capacity of 360mAh/ g is reserved after the 50-week cycle, and only 100mAh/ g is left with respect to the SiO after 10 weeks. The results show that the initial discharge capacity of the battery is 2131. 3mAh/ g, the first discharge capacity is 2131. 3mAh/ g, the first discharge capacity is 71.8%, and the capacity of 646. 5mAh/ g is retained after the 50-week cycle, compared with the use of PVDF The binder and the reversible capacity are large. In the same way, the PAN is used as a carbon source, and the SiO and the PAN are mixed by a ball milling method, and then the high-temperature heat treatment is carried out so that the PAN is cracked to obtain the SiO/ CNx composite material, and the ball milling method is more capable of ensuring the sufficient mixing of the PAN and the SiO and the PA for the sol-gel method. N utilization. When the heat treatment temperature is 500 掳 C, the first discharge capacity is 1180. 3mAh/ g, the first coulomb efficiency is 65. 9%, and the reversible capacity after 50 cycles is still maintained at 490mA When the heat treatment temperature is 500 掳 C, the cycle performance of the battery is the best, the first discharge capacity is 1396. 7mAh/ g, the first discharge capacity is 72.4%, and the capacity of 580. 9mAh/ g is reserved after the 50-week cycle, relative to the use of PVD F is a binder, and the reversible capacity is greatly improved, but the capacity attenuation of the battery is more serious, and further improvement is needed to improve the cycle stability. and the reversible capacity, and the SiO/ CN without the binder is synthesized by the 鈥渄irect coating method鈥
本文编号：2417923
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