片狀多孔碳材料的結(jié)構(gòu)調(diào)控及電化學性質(zhì)研究
發(fā)布時間：2018-10-10 17:46
【摘要】：碳材料具有良好的導電性和機械性能、結(jié)構(gòu)穩(wěn)定及形態(tài)豐富等特點,可以在鋰離子電池和超級電容器等高效儲能器件中構(gòu)筑能量儲存和輸運網(wǎng)絡,從而發(fā)揮著不可或缺的重要作用。片狀多孔碳材料的可控制備是增加碳基材料的儲能活性位點、構(gòu)筑更加高效便利的電荷傳輸通道的重要途徑,也是進一步提高儲能器件功率密度和能量密度的重要手段。本論文針對當前儲能電極材料存在的問題,結(jié)合碳材料在鋰離子電池和超級電容器中發(fā)揮的作用,通過結(jié)構(gòu)設計和可控制備,獲得一系列具有高效離子傳輸通道和導電網(wǎng)絡結(jié)構(gòu)的片狀多孔碳基材料,并將其應用于高效儲能器件中;在此基礎上發(fā)展了多種片狀多孔碳材料的制備方法,并對其形成機理進行分析闡釋,從而實現(xiàn)了片狀多孔碳材料微觀結(jié)構(gòu)的精確調(diào)控。針對高比容量錫基材料用作鋰離子電池負極存在導電性差和充放電過程中的體積效應等問題,制備了碳包覆空心錫與石墨烯雜化材料,通過利用各組分之間的協(xié)同效應實現(xiàn)了錫基雜化材料電化學性能的優(yōu)化,其首次可逆容量達922.7mAh g-1,經(jīng)50次循環(huán)后容量保持率為71.5%。研究并發(fā)展了片狀多孔碳材料的三種制備方法:一步碳化法、直接活化及模板法。通過一步碳化處理生物質(zhì)獲得高比表面積的片狀多孔碳材料。改變碳化溫度即可對孔結(jié)構(gòu)進行有效調(diào)節(jié),適用于不同的電解液體系。BCY-800在6 M KOH電解液體系下比容量高達216 F g-1,其在20 A g-1下的容量保持率為0.5 A g-1時的84%;BCY-900在離子液體體系中290 W L-1時對應的體積能量密度為64.6 Wh L-1,在3065 W L-1時體積能量密度仍高達34 Wh L-1。通過直接活化法實現(xiàn)片狀層次孔碳材料的可控制備。通過改變活化路徑實現(xiàn)了球形低聚物向片狀層次孔碳材料的轉(zhuǎn)變,并探討了其形成機理。球形低聚物的表面化學、活化溫度和活化劑的添加量對結(jié)構(gòu)的形成非常重要。片狀層次孔碳具有大比表面積(2633 m2 g-1)和相互貫通的多層級孔結(jié)構(gòu)等特征,在100 A g-1的大電流密度下其容量仍達184 F g-1,為0.5 A g-1下容量的71.6%;在1 A g-1的電流密度下循環(huán)2000圈后的容量保持率為98%。通過氧化石墨烯的模板誘導作用實現(xiàn)對生物質(zhì)原料水熱產(chǎn)物結(jié)構(gòu)和形貌的調(diào)控。利用KOH活化處理,獲得了比表面積達3257 m2 g-1的片狀多孔碳材料,在1000 mV s-1的高掃速下,材料的循環(huán)伏安曲線仍能保持良好的矩形形狀。
[Abstract]:Carbon materials have good electrical conductivity and mechanical properties, stable structure and rich shape. They can be used to build energy storage and transport network in high-efficiency energy storage devices such as lithium-ion batteries and supercapacitors. Thus play an indispensable and important role. The controllable preparation of sheet porous carbon materials is an important way to increase the energy storage activity sites of carbon based materials and to construct more efficient and convenient charge transfer channels. It is also an important means to further improve the power density and energy density of energy storage devices. In this paper, considering the problems existing in the materials of energy storage electrodes and the role of carbon materials in lithium ion batteries and supercapacitors, the structure design and controllable fabrication are adopted. A series of sheet porous carbon based materials with high efficiency ion transport channels and conductive network structure were obtained and applied to high efficiency energy storage devices. The formation mechanism was analyzed and explained, thus the precise regulation of the microstructure of porous carbon flake materials was realized. In order to solve the problems of poor conductivity and volume effect during charge and discharge of high specific capacity tin based materials used as anode of lithium ion batteries, carbon coated hollow tin and graphene hybrid materials were prepared. The electrochemical performance of tin based hybrid materials was optimized by using the synergistic effect of each component. The first reversible capacity of the hybrid material was up to 922.7mAh g-1, and the capacity retention rate was 71.5 after 50 cycles. Three preparation methods of sheet porous carbon materials were studied and developed: one step carbonization method, direct activation method and template method. Sheet porous carbon materials with high specific surface area were obtained by one step carbonization of biomass. The pore structure can be adjusted effectively by changing the carbonation temperature. It is suitable for different electrolyte systems. The specific capacity of BCY-800 in 6 M KOH electrolyte system is up to 216F g-1, and the volume energy density of BCY-900 in ionic liquid system at 290W L-1 is 84 when the capacity retention at 20A g ~ (-1) is 0.5 A g ~ (-1). The volume energy density is still up to 34 Wh L ~ (-1) at 3065 W ~ (-1). The controllable preparation of lamellar layered porous carbon materials was realized by direct activation method. The transition of spherical oligomers to lamellar porous carbon materials was realized by changing the activation path, and its formation mechanism was discussed. Surface chemistry, activation temperature and the amount of activator are very important for the formation of the structure of spherical oligomer. The flake layered porous carbon has the characteristics of large specific surface area (2633 m2 g ~ (-1) and interpenetrating multi-layer pore structure. At the high current density of 100A g ~ (-1), the capacity is still 184 F g ~ (-1), which is 71.6% of the capacity at 0.5 A g ~ (-1), and the capacity retention rate is 98% after cycling for 2000 cycles at the current density of 1 A g ~ (-1). The structure and morphology of hydrothermal products from biomass were regulated by template induction of graphene oxide. A sheet porous carbon material with a specific surface area of 3257 m2 / g ~ (-1) was obtained by KOH activation treatment. The cyclic voltammetry curve of the material remained a good rectangular shape at a high sweep rate of 1000 mV / s ~ (-1).
【學位授予單位】：天津大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TQ127.11
，
本文編號：2262714
[Abstract]:Carbon materials have good electrical conductivity and mechanical properties, stable structure and rich shape. They can be used to build energy storage and transport network in high-efficiency energy storage devices such as lithium-ion batteries and supercapacitors. Thus play an indispensable and important role. The controllable preparation of sheet porous carbon materials is an important way to increase the energy storage activity sites of carbon based materials and to construct more efficient and convenient charge transfer channels. It is also an important means to further improve the power density and energy density of energy storage devices. In this paper, considering the problems existing in the materials of energy storage electrodes and the role of carbon materials in lithium ion batteries and supercapacitors, the structure design and controllable fabrication are adopted. A series of sheet porous carbon based materials with high efficiency ion transport channels and conductive network structure were obtained and applied to high efficiency energy storage devices. The formation mechanism was analyzed and explained, thus the precise regulation of the microstructure of porous carbon flake materials was realized. In order to solve the problems of poor conductivity and volume effect during charge and discharge of high specific capacity tin based materials used as anode of lithium ion batteries, carbon coated hollow tin and graphene hybrid materials were prepared. The electrochemical performance of tin based hybrid materials was optimized by using the synergistic effect of each component. The first reversible capacity of the hybrid material was up to 922.7mAh g-1, and the capacity retention rate was 71.5 after 50 cycles. Three preparation methods of sheet porous carbon materials were studied and developed: one step carbonization method, direct activation method and template method. Sheet porous carbon materials with high specific surface area were obtained by one step carbonization of biomass. The pore structure can be adjusted effectively by changing the carbonation temperature. It is suitable for different electrolyte systems. The specific capacity of BCY-800 in 6 M KOH electrolyte system is up to 216F g-1, and the volume energy density of BCY-900 in ionic liquid system at 290W L-1 is 84 when the capacity retention at 20A g ~ (-1) is 0.5 A g ~ (-1). The volume energy density is still up to 34 Wh L ~ (-1) at 3065 W ~ (-1). The controllable preparation of lamellar layered porous carbon materials was realized by direct activation method. The transition of spherical oligomers to lamellar porous carbon materials was realized by changing the activation path, and its formation mechanism was discussed. Surface chemistry, activation temperature and the amount of activator are very important for the formation of the structure of spherical oligomer. The flake layered porous carbon has the characteristics of large specific surface area (2633 m2 g ~ (-1) and interpenetrating multi-layer pore structure. At the high current density of 100A g ~ (-1), the capacity is still 184 F g ~ (-1), which is 71.6% of the capacity at 0.5 A g ~ (-1), and the capacity retention rate is 98% after cycling for 2000 cycles at the current density of 1 A g ~ (-1). The structure and morphology of hydrothermal products from biomass were regulated by template induction of graphene oxide. A sheet porous carbon material with a specific surface area of 3257 m2 / g ~ (-1) was obtained by KOH activation treatment. The cyclic voltammetry curve of the material remained a good rectangular shape at a high sweep rate of 1000 mV / s ~ (-1).
【學位授予單位】：天津大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TQ127.11
，
本文編號：2262714
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