氧化還原摻雜的聚合物：一類新穎的高容量二次電池正極材料
發(fā)布時間：2018-09-12 07:42
【摘要】：能源危機(jī)與環(huán)境污染是當(dāng)今人類社會面對的嚴(yán)重問題。探索和發(fā)展先進(jìn)的儲能方式是解決能源問題的關(guān)鍵技術(shù)之一。鋰離子電池由于綜合性能優(yōu)異,被認(rèn)為是最具潛力的高比能儲電體系。然而現(xiàn)階段,鋰離子電池的能量密度主要受限于正極材料的比容量。商品化鋰離子電池的正極材料主要是過渡金屬氧化物。由于無機(jī)剛性晶格的限制,理論比容量很難有所突破。以碳元素為基本骨架的導(dǎo)電聚合物由于導(dǎo)電性好,理論比容量高,氧化還原可逆性好,價(jià)格低廉,環(huán)境友好等特點(diǎn),是理想的二次電池正極材料。然而由于活性物質(zhì)利用率低,聚合物實(shí)際容量遠(yuǎn)遠(yuǎn)低于理論容量。本文旨在探索提高導(dǎo)電聚合物容量利用率的新方法,以實(shí)現(xiàn)最大程度地釋放聚合物的潛在容量,從而開發(fā)高性能,低成本的導(dǎo)電聚合物二次電池材料。主要研究內(nèi)容和研究結(jié)果如下： 1.以聚吡咯為研究模型,通過氧化還原固定化摻雜的方式合成了Fe (CN)64-摻雜的聚吡咯復(fù)合材料PPy/FC,并考察了該材料作為鋰離子電池正極材料的電化學(xué)性能。實(shí)驗(yàn)結(jié)果表明,相對于未摻雜的PPy,經(jīng)過Fe (CN)64-摻雜的PPy (PPy/FC)的充放電容量提高了3倍以上,接近145mAh g-1,且循環(huán)100周后容量保持率可以達(dá)到80%；以400mA g-1的電流密度充放電時,放電比容量仍然有110mAh g-1.對該聚合物復(fù)合材料充放電機(jī)理的探究表明,由于大陰離子Fe(CN)64-對PPy的固定化摻雜作用,PPy/FC的充放電機(jī)理由傳統(tǒng)的陰離子摻雜-脫雜過程變成了體積較小的陽離子(Li+)的嵌入-脫出反應(yīng),并且Fe (CN)64-/Fe (CN)63-電對在充放電過程中也通過自身的氧化還原反應(yīng)為體系提供額外的容量。同時,Fe (CN)64-/Fe (CN)63-電對的存在,也對PPy主鏈存在顯著的活化效應(yīng)。 2.為了驗(yàn)證氧化還原摻雜對聚合物主鏈活化的普適性,實(shí)驗(yàn)分別使用了不同的摻雜劑,不同的聚合物主鏈以及不同的溶液體系。首先以聚吡咯為研究模型,分別采用不同類型的氧化還原摻雜劑(金屬配合物類,過渡金屬含氧酸鹽類,有機(jī)氧化還原基團(tuán))對PPy摻雜。摻雜后的聚合物復(fù)合材料的電化學(xué)容量呈現(xiàn)出顯著的提高,并且具有良好的電化學(xué)性能。以二苯胺磺酸根摻雜的聚吡咯(PPy/DS)為例,在50mA g-1的電流密度下可逆放電容量達(dá)到143mAh g-1,100周后容量保持率為87%。當(dāng)充放電電流密度提高到1600mA g-1時,可逆放電容量仍然可以達(dá)到50mAh g-1.。同時,我們以Fe(CN)64-為摻雜劑,分別對聚苯胺,聚二苯胺,聚(3,4-二氧乙烯噻吩)摻雜,得到聚合物復(fù)合材料PAn/FC, PDPA/FC,PEDOT/FC。相對于本征態(tài)聚合物,這些聚合物復(fù)合材料的電化學(xué)容量都呈現(xiàn)出顯著的提高,并且循環(huán)穩(wěn)定。最后,我們將氧化還原固定化摻雜所得的聚合物復(fù)合材料PPy/FC, PPy/DS用于鈉離子電解液中進(jìn)行充放電測試。與在鋰離子電池中相同,經(jīng)過摻雜后的聚合物復(fù)合材料呈現(xiàn)出顯著的容量倍增效應(yīng)。PPy/FC在鈉離子電池中以50mAg-1的電流密度充放電,放電容量達(dá)到135mAhg-1,循環(huán)100周后容量保持率為82%,并且大電流充放電性能良好。PPy/DS在50mA g-1的電流密度下放電容量也可以達(dá)到135mAhg-1,并且具有良好的循環(huán)穩(wěn)定性與倍率性能。 3.針對氧化還原固定化摻雜的摻雜度低,由活性摻雜劑提供的電化學(xué)容量有限這個問題,我們合成了多個氧化還原活性基團(tuán)復(fù)合的導(dǎo)電聚合物-聚(1,5-二氨基蒽醌)(PDAQ),并將其與氣相炭纖維(VGCF)復(fù)合制備了PDAQ/C,考察了其室溫下在鋰離子電解液中的電化學(xué)性能。實(shí)驗(yàn)結(jié)果表明：PDAQ/C復(fù)合材料在20mA g-1的電流密度下,首周放電容量達(dá)到285mAh g-1,循環(huán)200周后,放電容量為160mAh g-1。當(dāng)電流密度提高到800mA g-1時,放電容量仍然可以達(dá)到125mAh g-1。對該聚合物復(fù)合材料充放電機(jī)理的探究表明,該材料的放電容量主要包括兩個部分：一是聚苯胺主鏈的摻雜脫雜；另一部分是醌基(Q)的氧化還原反應(yīng)。 4.對于氧化還原固定化摻雜,雖然大幅提高聚合物的電化學(xué)容量,但距其潛在的理論容量仍有差距。為了探索新的方法,我們合成了自摻雜聚合物-聚二苯胺磺酸鈉(PDS),實(shí)現(xiàn)了聚合物主鏈100%摻雜,并探索了該材料作為鈉離子電池正極材料的可行性。實(shí)驗(yàn)結(jié)果表明,以50mA g-1的電流密度充放電,放電容量接近其理論值99mAhg-1,充放電平臺在3.6V左右。循環(huán)50周后,當(dāng)電流密度達(dá)到400mA g-1時,放電容量為43mAh g-1。而且相對于普通的導(dǎo)電聚合物,該自摻雜聚合物富含鈉源,為解決實(shí)用化正負(fù)極匹配問題提供方便。通過對該材料充放電機(jī)理的探究表明,PDS充放電過程對應(yīng)于陽離子Na+的嵌入脫出。
[Abstract]:Energy crisis and environmental pollution are serious problems facing human society nowadays. Exploring and developing advanced energy storage methods is one of the key technologies to solve energy problems. Lithium-ion batteries are considered as the most potential high-specific energy storage system because of their excellent comprehensive performance. However, the energy density of lithium-ion batteries is mainly limited at this stage. Specific capacity of cathode materials. Transition metal oxides are the main cathode materials for commercial lithium-ion batteries. Due to the limitation of inorganic rigid lattice, theoretical specific capacity is difficult to break through. It is an ideal cathode material for secondary batteries. However, due to the low utilization of active materials, the actual capacity of the polymer is far lower than the theoretical capacity. Two battery materials. The main research contents and research results are as follows:
1. Fe(CN)64-doped PPy/FC composites were synthesized by redox immobilization doping method with polypyrrole as the research model. The electrochemical properties of the composites as cathode materials for lithium-ion batteries were investigated. The results showed that the charge-discharge capacitance of Fe(CN)64-doped PPy(PPy/FC) was higher than that of undoped PPy. The specific discharge capacity of PPy/FC was 110 mAh g-1 when the current density of 400 mA g-1 was charged and discharged. The charge-discharge mechanism of the polymer composite was studied. The results showed that the charge-discharge mechanism of PPy/FC was due to the immobilization and doping of large anion Fe(CN)64-on PPy. The traditional anion doping-dehybridization process has been changed into a small cation (Li+) intercalation-dehybridization reaction, and the Fe(CN)64-/Fe(CN)63-pair also provides additional capacity for the system through its own redox reaction during charging and discharging. At the same time, the existence of Fe(CN)64-/Fe(CN)63-pair also shows the presence of PPy main chain. The activation effect.
2. In order to verify the universality of redox doping on the activation of polymer backbone chain, different dopants, different polymer backbone chains and different solution systems were used in the experiments. The electrochemical capacity of PPy-doped polymer composites was significantly improved and the electrochemical properties of the composites were good. Taking PPy/DS doped with diphenylamine sulfonate as an example, the reversible discharge capacity reached 143 mAh g-1 at the current density of 50 mA g-1, and the capacity retention rate was 87% after 100 weeks. The reversible discharge capacity of PAn/FC, PDPA/FC and PEDOT/FC composites can still reach 50 mAh g-1 when charge-discharge current density increases to 1600 mA g-1. At the same time, we doped polyaniline, Polydiphenylamine and poly (3,4-dioxyethylene thiophene) with Fe (CN) 64 - as dopant, respectively, and obtained polymer composites PAn/FC, PDPA/FC and PEDOT/FC. At last, we used PPy/FC and PPy/DS to test the charge-discharge performance of sodium ion electrolyte. As in lithium ion batteries, the doped polymer composites showed significant capacity. The discharge capacity of PPy/FC was 135 mAhg-1, and the capacity retention rate was 82% after 100 weeks of cycling. The capacitance of PPy/DS could reach 135 mAhg-1 at the current density of 50 mAg-1. Yes.
3. In view of the low doping degree of redox immobilized dopants and the limited electrochemical capacity provided by active dopants, we synthesized poly (1,5-diaminoanthraquinone) (PDAQ) with multiple redox active groups, and prepared PDAQ/C by compounding PDAQ with vapor-phase carbon fiber (VGCF) at room temperature. The experimental results show that the discharge capacity of PDAQ/C composites reaches 285mAh g-1 in the first week at the current density of 20 mA g-1, and 160 mAh g-1 after 200 cycles. When the current density is raised to 800 mA g-1, the discharge capacity can still reach 125 mAh g-1. The charge-discharge machine for PDAQ/C Composites The results show that the discharge capacity of the material mainly consists of two parts: one is doping and dehybridization of the main chain of polyaniline, the other is redox reaction of quinone group (Q).
4. For redox immobilized doping, although the electrochemical capacity of the polymer is greatly improved, there is still a gap from its potential theoretical capacity. In order to explore new methods, we synthesized a self-doped polymer-sodium Polydiphenylamine sulfonate (PDS) and realized 100% doping of the main chain of the polymer, and explored this material as the cathode material for sodium ion batteries. The experimental results show that the discharge capacity is close to the theoretical value of 99 mAhg-1 and the plateau of charge and discharge is about 3.6 V. After 50 weeks of cycling, when the current density reaches 400 mAg-1, the discharge capacity is 43 mAhg-1. Compared with ordinary conductive polymer, the self-doped polymer is rich in sodium source, which is the solution. The charge-discharge mechanism of PDS is studied and it is shown that the charge-discharge process of PDS corresponds to the intercalation and detachment of cationic Na +.
【學(xué)位授予單位】：武漢大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TM912;O631.3
本文編號：2238354
[Abstract]:Energy crisis and environmental pollution are serious problems facing human society nowadays. Exploring and developing advanced energy storage methods is one of the key technologies to solve energy problems. Lithium-ion batteries are considered as the most potential high-specific energy storage system because of their excellent comprehensive performance. However, the energy density of lithium-ion batteries is mainly limited at this stage. Specific capacity of cathode materials. Transition metal oxides are the main cathode materials for commercial lithium-ion batteries. Due to the limitation of inorganic rigid lattice, theoretical specific capacity is difficult to break through. It is an ideal cathode material for secondary batteries. However, due to the low utilization of active materials, the actual capacity of the polymer is far lower than the theoretical capacity. Two battery materials. The main research contents and research results are as follows:
1. Fe(CN)64-doped PPy/FC composites were synthesized by redox immobilization doping method with polypyrrole as the research model. The electrochemical properties of the composites as cathode materials for lithium-ion batteries were investigated. The results showed that the charge-discharge capacitance of Fe(CN)64-doped PPy(PPy/FC) was higher than that of undoped PPy. The specific discharge capacity of PPy/FC was 110 mAh g-1 when the current density of 400 mA g-1 was charged and discharged. The charge-discharge mechanism of the polymer composite was studied. The results showed that the charge-discharge mechanism of PPy/FC was due to the immobilization and doping of large anion Fe(CN)64-on PPy. The traditional anion doping-dehybridization process has been changed into a small cation (Li+) intercalation-dehybridization reaction, and the Fe(CN)64-/Fe(CN)63-pair also provides additional capacity for the system through its own redox reaction during charging and discharging. At the same time, the existence of Fe(CN)64-/Fe(CN)63-pair also shows the presence of PPy main chain. The activation effect.
2. In order to verify the universality of redox doping on the activation of polymer backbone chain, different dopants, different polymer backbone chains and different solution systems were used in the experiments. The electrochemical capacity of PPy-doped polymer composites was significantly improved and the electrochemical properties of the composites were good. Taking PPy/DS doped with diphenylamine sulfonate as an example, the reversible discharge capacity reached 143 mAh g-1 at the current density of 50 mA g-1, and the capacity retention rate was 87% after 100 weeks. The reversible discharge capacity of PAn/FC, PDPA/FC and PEDOT/FC composites can still reach 50 mAh g-1 when charge-discharge current density increases to 1600 mA g-1. At the same time, we doped polyaniline, Polydiphenylamine and poly (3,4-dioxyethylene thiophene) with Fe (CN) 64 - as dopant, respectively, and obtained polymer composites PAn/FC, PDPA/FC and PEDOT/FC. At last, we used PPy/FC and PPy/DS to test the charge-discharge performance of sodium ion electrolyte. As in lithium ion batteries, the doped polymer composites showed significant capacity. The discharge capacity of PPy/FC was 135 mAhg-1, and the capacity retention rate was 82% after 100 weeks of cycling. The capacitance of PPy/DS could reach 135 mAhg-1 at the current density of 50 mAg-1. Yes.
3. In view of the low doping degree of redox immobilized dopants and the limited electrochemical capacity provided by active dopants, we synthesized poly (1,5-diaminoanthraquinone) (PDAQ) with multiple redox active groups, and prepared PDAQ/C by compounding PDAQ with vapor-phase carbon fiber (VGCF) at room temperature. The experimental results show that the discharge capacity of PDAQ/C composites reaches 285mAh g-1 in the first week at the current density of 20 mA g-1, and 160 mAh g-1 after 200 cycles. When the current density is raised to 800 mA g-1, the discharge capacity can still reach 125 mAh g-1. The charge-discharge machine for PDAQ/C Composites The results show that the discharge capacity of the material mainly consists of two parts: one is doping and dehybridization of the main chain of polyaniline, the other is redox reaction of quinone group (Q).
4. For redox immobilized doping, although the electrochemical capacity of the polymer is greatly improved, there is still a gap from its potential theoretical capacity. In order to explore new methods, we synthesized a self-doped polymer-sodium Polydiphenylamine sulfonate (PDS) and realized 100% doping of the main chain of the polymer, and explored this material as the cathode material for sodium ion batteries. The experimental results show that the discharge capacity is close to the theoretical value of 99 mAhg-1 and the plateau of charge and discharge is about 3.6 V. After 50 weeks of cycling, when the current density reaches 400 mAg-1, the discharge capacity is 43 mAhg-1. Compared with ordinary conductive polymer, the self-doped polymer is rich in sodium source, which is the solution. The charge-discharge mechanism of PDS is studied and it is shown that the charge-discharge process of PDS corresponds to the intercalation and detachment of cationic Na +.
【學(xué)位授予單位】：武漢大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TM912;O631.3
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