SiO作為鋰離子電池負(fù)極材料的改性研究
發(fā)布時間：2019-01-30 07:58
【摘要】：硅由于在地殼中含量高，理論處理容量高達(dá)4200mAh/g,放電電壓低而且安全性能優(yōu)越成為鋰離子電池負(fù)極材料的研究熱點。但是，硅在深度脫嵌鋰時體積效應(yīng)大，易與導(dǎo)電介質(zhì)集流體失去電接觸導(dǎo)致的循環(huán)性能差、首次庫倫效率低而且硅材料本身低導(dǎo)電率等限制了其在鋰離子電池中商業(yè)化應(yīng)用。改善硅基材料循環(huán)性能，緩沖其在循環(huán)過程中的體積膨脹并提高其導(dǎo)電性能成為硅基材料改性的主要方向。 本文主要以PAN（聚丙烯腈）為碳源通過不同的方法來制備SiO/CNx復(fù)合材料來作為鋰離子電池的負(fù)極材料，此外，通過改變粘結(jié)劑來涂片研究粘結(jié)劑對復(fù)合材料電化學(xué)性能的影響。運(yùn)用X射線衍射測試(XRD)、拉曼光譜(Raman)、傅里葉紅外變換光譜(FT-IR)、X射線電子能譜(XPS)、掃描電子顯微鏡(SEM)了解復(fù)合材料的結(jié)構(gòu)以及形貌特征，從這方面的改變來探討材料改性的效果。用復(fù)合材料作為鋰離子電池負(fù)極材料的電化學(xué)性能分別通過恒電流充放電、循環(huán)伏安(CV)、交流阻抗(EIS)的測試，了解復(fù)合材料的電化學(xué)性能。 以PAN為碳源，采用溶膠凝膠法與SiO混合，(質(zhì)量比:PAN:SiO=3:7),在氬氣下高溫煅燒使PAN裂解后得到SiO/CNx復(fù)合材料，研究了溫度對復(fù)合材料性能的影響。用PVDF作粘結(jié)劑，，當(dāng)熱處理溫度為500°C時，得到的SiO/CNx復(fù)合材料性能最佳，首次放電容量為2009.3mAh/g，首次庫倫效率為64.8%，經(jīng)過50周循環(huán)后仍有360mAh/g的容量保留，相對于SiO經(jīng)過10周僅剩100mAh/g有很大的提高。用海藻酸鈉代替PVDF作粘結(jié)劑，當(dāng)熱處理溫度為500°C時，電池的循環(huán)性能最好，首次放電容量為為2131.3mAh/g，首次庫倫效率為71.8%，經(jīng)過50周循環(huán)后仍有646.5mAh/g的容量保留，相對于使用PVDF作粘結(jié)劑，可逆容量有較大的提高。 同樣以PAN為碳源，改用球磨法將SiO和PAN進(jìn)行混合，然后高溫?zé)崽幚硎沟肞AN裂解得到SiO/CNx復(fù)合材料，球磨法相對于溶膠凝膠法來說更能保證PAN和SiO的充分混合以及PAN的利用率。當(dāng)熱處理溫度為500°C時，首次放電容量為1180.3mAh/g，首次庫倫效率為65.9%，經(jīng)過50周循環(huán)后可逆容量仍保持在490mAh/g左右。用海藻酸鈉代替PVDF作粘結(jié)劑，當(dāng)熱處理溫度為500°C時，電池的循環(huán)性能最好，首次放電容量為為1396.7mAh/g，首次庫倫效率為72.4%，經(jīng)過50周循環(huán)后仍有580.9mAh/g的容量保留，相對于使用PVDF作粘結(jié)劑，可逆容量有較大的提高，但電池的容量衰減較為嚴(yán)重，需要進(jìn)一步改善來提高循環(huán)穩(wěn)定性以及可逆容量。 通過“直接涂膜法”合成無需粘結(jié)劑的SiO/CNx復(fù)合材料電極。由于購買的SiO是微米級的，先通過球磨將微米級的SiO顆粒粒徑減小到微納米級別，命名為“milled SiO”。然后將“milled SiO”與PAN在DMF溶液中均勻混合，直至形成漿狀物，將漿狀物直接涂布在銅箔集流體上，然后在真空中80°C干燥，再將極片在Ar保護(hù)的管式爐中進(jìn)行熱處理，得到無需粘結(jié)劑的SiO/CNx復(fù)合材料電極。由于在熱處理過程中，PAN裂解形成含氮的碳網(wǎng)包覆在“milled SiO”的表面，使得材料的導(dǎo)電性能和循環(huán)性能都有很大的提高。當(dāng)熱處理溫度為500°C時，復(fù)合材料首次放電容量為2733.7mAh/g，首次庫倫效率為74.9%，經(jīng)過100次循環(huán)后容量仍有927.8mAh/g，相對于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 擄 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 擄 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 擄 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
本文編號：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 擄 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 擄 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 擄 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
本文編號：2417923
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