本文選題：硬炭 + 活性炭　； 參考：《天津大學(xué)》2014年碩士論文

【摘要】：隨著電池和電容器應(yīng)用范圍的不斷擴(kuò)大，對(duì)于這些儲(chǔ)能元件的能量密度、功率密度、循環(huán)壽命等性能的要求也越來越高。鋰離子電容器（LIC）因兼具電化學(xué)電容器良好的功率特性和鋰離子電池較高的能量密度而引起人們的關(guān)注。從鋰離子電容器未來的產(chǎn)業(yè)化角度出發(fā)，炭材料因?yàn)榱畠r(jià)易得是鋰離子電容器的首選材料。本論文以商品化的活性炭為正極、硬炭為負(fù)極，1M LiPF6/EC+DEC為電解液組裝了鋰離子電容器，考察了負(fù)極預(yù)鋰化容量、預(yù)鋰化工藝、正負(fù)極質(zhì)量配比對(duì)鋰離子電容器電化學(xué)性能的影響。 將硬炭/Li半電池進(jìn)行不同程度放電以獲取不同預(yù)鋰化容量的硬炭，并將得到的預(yù)鋰化硬炭用于LIC。研究發(fā)現(xiàn)，當(dāng)負(fù)極嵌鋰容量小于200mAh/g時(shí)，LIC的首次效率很低，正極會(huì)發(fā)生高壓極化，超出了活性炭的穩(wěn)定電壓區(qū)間；當(dāng)嵌鋰容量大于200mAh/g時(shí)，負(fù)極的不可逆容量因得到了充分補(bǔ)償，LIC的效率在90%以上。隨著嵌鋰容量的增加，LIC的能量密度增加，然而當(dāng)嵌鋰容量超過400mAh/g時(shí)，負(fù)極會(huì)發(fā)生鋰的沉積。在負(fù)極嵌鋰容量不同的條件下，以嵌鋰容量為400mAh/g的LIC綜合性能最優(yōu)，其具有最小的擴(kuò)散電阻，最高能量密度和功率密度分別為76.5Wh/kg和5.1kW/kg，且循環(huán)1000次后，能量保持率仍高達(dá)92.0%。 利用硬炭與鋰源自放電這種簡單方法對(duì)LIC負(fù)極進(jìn)行了預(yù)鋰化，結(jié)果表明該種方法能成功實(shí)現(xiàn)負(fù)極的預(yù)鋰化。LIC的比容量隨著預(yù)鋰化時(shí)間的延長先增大后減小，其最佳預(yù)鋰化時(shí)間為15h。經(jīng)過15h預(yù)鋰化的鋰離子電容器最高能量密度可達(dá)97.2Wh/kg，即使在功率密度為5.4kW/kg的條件下，其依然具有45.1Wh/kg的能量密度，同時(shí)該電容器具有最小的阻抗和良好的循環(huán)性能（1A/g的電流密度下循環(huán)1000次后，能量保持率為91.2%）。 通過改變正負(fù)極質(zhì)量配比，對(duì)LIC的電化學(xué)性能進(jìn)行進(jìn)一步優(yōu)化。結(jié)果表明，當(dāng)正負(fù)極質(zhì)量配比為2.2時(shí)，電容器具有最優(yōu)的電化學(xué)性能。電流密度從1.2C增加到82C時(shí)，，電容器的能量密度由88.7Wh/kg衰減到48.7Wh/kg，能量保持率為57.0%。同時(shí)，電容器具有非常小的電荷轉(zhuǎn)移內(nèi)阻（10.4），最大能量密度和功率密度分別為88.7Wh/kg和12kW/kg。
[Abstract]:With the continuous expansion of battery and capacitor applications, the energy density, power density, cycle life and other performance requirements of these energy storage elements are becoming higher and higher. Lithium-ion capacitors (LICs) have attracted much attention because of their good power characteristics and high energy density of lithium-ion batteries. From the point of view of the future industrialization of lithium ion capacitors, carbon materials are the preferred materials for lithium ion capacitors because of their low cost. In this paper, the lithium ion capacitor was assembled with commercial activated carbon as positive electrode and hard carbon as negative electrode with 1m LiPF6/EC DEC as electrolyte. The effects of prelithiation capacity, prelithiation process and mass ratio of positive and negative electrode on electrochemical performance of lithium ion capacitor were investigated. The hard carbon with different prelithiation capacity was obtained by discharging the hard carbon / Li half-cell to different degree, and the obtained prelithiated hard carbon was used for LICs. It is found that when the lithium intercalation capacity of the negative electrode is less than 200mAh/g, the initial efficiency is very low, and the positive electrode will be polarized at high pressure, which exceeds the stable voltage range of the activated carbon, and when the lithium intercalation capacity is greater than 200mAh/g, The irreversible capacity of the negative electrode is more than 90% due to the efficiency of fully compensating the LIC. With the increase of the lithium intercalation capacity, the energy density of the LIC increases, but when the lithium intercalation capacity exceeds the 400mAh/g, the lithium deposition will occur in the negative electrode. Under the condition of different lithium intercalation capacity, the LIC with lithium intercalation capacity as 400mAh/g has the best comprehensive performance. It has the smallest diffusive resistance, the highest energy density and power density are 76.5Wh/kg and 5.1 kW / kg, respectively. After 1000 cycles, the energy retention rate is still up to 92. 0%. The simple method of self-discharge of hard carbon and lithium source is used to prelithiate the LIC anode. The results show that the specific capacity of prelithium. LIC of negative electrode increases first and then decreases with the prolongation of prelithiation time. The optimum prelithiation time is 15 h. The maximum energy density of the lithium-ion capacitor after 15 h pre-lithiation can reach 97.2Wh-1 / kg, even when the power density is 5.4kW/kg, it still has the energy density of 45.1Wh/kg. At the same time, the capacitor has the minimum impedance and good cycling performance. After 1000 cycles at 1 / g current density, the energy retention rate is 91.2%. The electrochemical performance of LIC was further optimized by changing the mass ratio of positive and negative electrodes. The results show that the capacitor has the best electrochemical performance when the mass ratio of positive and negative electrode is 2.2. When the current density is increased from 1.2C to 82C, the energy density of the capacitor attenuates from 88.7Wh/kg to 48.7 Wha / kg, and the energy retention rate is 57.0 / kg. At the same time, the capacitor has a very small charge transfer resistance of 10.4%, the maximum energy density and power density are 88.7Wh/kg and 12kW / KG, respectively.
【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TM53

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