本文選題：鋰離子電池　切入點(diǎn)：高電壓　出處：《南開大學(xué)》2014年博士論文　論文類型：學(xué)位論文

【摘要】：鋰離子電池在消費(fèi)類電子中得到了廣泛的應(yīng)用,在純電驅(qū)動汽車和混合動力汽車中處于規(guī)模應(yīng)用階段,在電網(wǎng)儲能領(lǐng)域則處于性能考核及驗(yàn)證階段,而汽車和儲能行業(yè)對所采用電池體系的壽命、安全性和成本等提出了更高的要求。目前應(yīng)用于消費(fèi)類電子的產(chǎn)業(yè)化鋰離子電池負(fù)極材料均采用石墨類材料,其具有離子和電子傳導(dǎo)性好、結(jié)構(gòu)穩(wěn)定和嵌鋰電位低等優(yōu)點(diǎn)；但在反復(fù)充放電過程中,鋰離子易在石墨負(fù)極沉積產(chǎn)生鋰枝晶,進(jìn)而刺穿電池隔膜而導(dǎo)致安全隱患或事故。因此,尋找安全型負(fù)極材料是電動汽車和儲能行業(yè)用鋰離子電池的重要研究方向之一。在安全型負(fù)極材料中,尖晶石結(jié)構(gòu)的鈦酸鋰材料由于其獨(dú)特的性能和結(jié)構(gòu)優(yōu)勢而備受關(guān)注,成為安全型鋰離子電池的首選負(fù)極材料之一。鈦酸鋰材料相對于金屬鋰的電位高(1.5V, vs Li/Li+),因此采用鈦酸鋰做負(fù)極材料的鋰離子電池的工作電壓和能量密度較低。本論文重點(diǎn)研究以鈉離子取代鋰離子制備納米結(jié)構(gòu)的鈦酸鋰材料,以期構(gòu)筑鈦酸鋰材料的新結(jié)構(gòu),降低電位平臺；采用商業(yè)化的微米級高電壓LiNi0.5Mn1.5O4正極材料與研制的具有低電勢的鈦基負(fù)極材料配對制備軟包裝鋰離子電池,開展電池性能研究與評價,以期提升電池的電壓。 本論文在以下三個方面開展了相關(guān)研究工作： 一、Li4-xNaxTi5O12負(fù)極材料的合成及電化學(xué)性能研究 將二氧化鈦、無水碳酸鋰和無水碳酸鈉混合,采用高溫?zé)Y(jié)的方法,鈉離子逐步取代鋰離子,制備出Li4-xNaxTi5O12材料。可以明顯地看出,隨著Li4-xNaxTi5O12材料中鈉離子和鋰離子摩爾比例的逐漸提升,所制備材料的相結(jié)構(gòu)由立方結(jié)構(gòu)轉(zhuǎn)變?yōu)樾狈骄ЫY(jié)構(gòu)(LiNaTi3O7),最后轉(zhuǎn)變?yōu)榱浇Y(jié)構(gòu)(Na4Ti5O12)。同時隨著鈉離子取代量的增加,所制備樣品的晶體尺寸增大。鈉離子取代鋰離子后,所制備樣品的放電容量有所降低,但材料的電勢平臺降低。尤其是Li2Na2Ti5O12材料樣品,具有單一相結(jié)構(gòu),電位平臺低且傾斜。因此,通過適量的鈉離子取代鈦酸鋰材料中的鋰離子,可提升所制備材料的電化學(xué)性能,如電勢平臺、放電容量和高倍率能力等。 二、Li2-xNaxTi3O7負(fù)極材料的合成與電化學(xué)性能研究 以Li2Ti307為基,采用鈉離子替代的方式制備了Li2-xNaxTi3O7負(fù)極材料,研究了鈉離子逐步替代對材料的電化學(xué)性能影響。研究顯示,隨著鈉離子摻雜量的增加,晶體從斜方錳礦型的Li2Ti3O7相逐漸轉(zhuǎn)變?yōu)樾狈骄ЫY(jié)構(gòu)的LiNaTi3O7相。適量鈉離子取代可實(shí)現(xiàn)材料的低電勢及傾斜的電勢平臺。同時,鈉離子的引入可節(jié)省鋰資源,降低材料成本。 三、Li2Na2Ti5O12/LiNi0.5Mn1.5O4軟包裝鋰離子電池性能研究 采用鈉離子部分替代鋰離子制備的Li2Na2Ti5O12材料和商業(yè)化的Li4Ti5O12材料,與商業(yè)化的高電壓尖晶石LiNi0.5Mn1.5O4材料匹配,組裝成軟包裝鋰離子電池。電池測試性能表明,采用具有低電勢的Li2Na2Ti5O12負(fù)極材料的確可以提升電池體系的放電電壓,實(shí)現(xiàn)了本論文的預(yù)期設(shè)計(jì)思路。其中,在0.05C放電條件和相同比例放電容量(30%)下,采用Li2Na2Ti5O12負(fù)極的電池放電電壓比采用Li4Ti5O12負(fù)極的電池高出約0.25V。 綜上所述,通過鈉離子替代鋰離子制備了納米結(jié)構(gòu)鈦酸鋰材料,適宜的替代量提升了材料的電化學(xué)性能,如電勢平臺、放電容量和高倍率能力等。制備的Li2Na2Ti5O12樣品具有單一相,電位平臺低且傾斜,具有良好的放電容量和倍率性能,同時降低了工作電勢,可提高鋰離子電池的工作電壓；所采用的商業(yè)化微米級高電壓鎳錳酸鋰(LiNi0.5M1.5O4)材料具有良好的電化學(xué)性能,采用研制的Li2Na2Ti5O12材料與之匹配制備軟包裝鋰離子電池,提升了鋰離子電池的工作電壓,這為現(xiàn)有高性能材料改性研究和新型高性能材料研發(fā)提供了新思路。
[Abstract]:Lithium ion battery has been widely used in consumer electronics, in pure electric drive in the stage of large-scale application and hybrid vehicles, in the performance appraisal and field verification stage in grid storage, and storage of the car and battery life system industry, put forward higher requirements for safety and cost. At present, in the consumer electronics industry of lithium ion battery anode materials are used graphite materials with ionic and electronic conductivity, stable structure and intercalation potential advantages; but in repeated charge and discharge process of lithium ion, easy to produce lithium dendrite in graphite anode deposition, and then pierce the battery the diaphragm and lead to safety problems or accidents. Therefore, looking for safe type anode materials for electric vehicles and energy storage industry is an important research direction for lithium ion batteries. In safety type cathode material, spinel The lithium titanate material structure has attracted much attention because of its unique structure and performance advantages, become one of the safety type lithium ion battery cathode material lithium titanate. The preferred material relative to the potential of lithium metal (1.5V, vs, Li/Li+) high, so using lithium titanate as the cathode material of lithium from the work voltage and energy density than batteries low. This paper focuses on the study on sodium ion substituted lithium ion preparation of lithium titanate nano structural material, in order to build a new structure of lithium titanate material, reducing the potential platform; a micron high voltage LiNi0.5Mn1.5O4 cathode material and the development of the commercial material has a low potential of titanium based anode materials for preparation of soft package lithium pairing ion battery, carry out research and evaluation in order to improve the performance of the battery voltage, battery.
This paper has carried out relevant research work in the following three aspects:
Synthesis and electrochemical properties of Li4-xNaxTi5O12 negative electrode
The titanium dioxide, anhydrous lithium carbonate and anhydrous sodium carbonate mixed by high temperature sintering method, the sodium ion gradually replace the lithium ion, the preparation of Li4-xNaxTi5O12 materials. It can be clearly seen, with the gradually enhanced Li4-xNaxTi5O12 materials of sodium ion and lithium ion molar ratio, phase structure of the prepared materials changed from cubic structure for cable square crystal structure (LiNaTi3O7), and finally into the six party structure (Na4Ti5O12). At the same time, with the increasing amount of sodium ion substitution, the crystal size of the sample increases. The sodium ion substituted lithium ion, the discharge capacity of the sample decreased, but the potential platform material especially Li2Na2Ti5O12 material samples decreased. That has a single phase structure, and low potential platform tilt. Therefore, lithium ion lithium titanate material to replace the sodium ions through proper, can improve the electrochemical performance of as prepared materials, such as potential platform, Discharge capacity and high rate capacity and so on.
Study on the synthesis and electrochemical properties of two, Li2-xNaxTi3O7 negative electrode
Based on Li2Ti307, Li2-xNaxTi3O7 cathode materials were synthesized by sodium ion substitution method was studied, the sodium ion gradually replace the influence the electrochemical performance of the composites. The results show that with the increase of sodium ion doping, Li2Ti3O7 crystal from the ramsdellite type phase gradually transforms to the orthorhombic structure of the LiNaTi3O7 phase. The amount of sodium ion replace the potential platform can realize the low potential and inclined material. At the same time, the introduction of sodium ions can save lithium resources, reduce the material cost.
Study on the performance of three, Li2Na2Ti5O12/LiNi0.5Mn1.5O4 soft packed lithium ion battery
The sodium ion substitution of lithium ion Li2Na2Ti5O12 materials prepared and commercial Li4Ti5O12 materials, and high voltage spinel LiNi0.5Mn1.5O4 material business, assembled into a soft package lithium ion battery. The battery test showed that the performance of using Li2Na2Ti5O12 cathode materials with low potential can indeed enhance the discharge voltage of the battery system, to achieve the desired design ideas of this paper. Among them, in the same proportion and discharge conditions of 0.05C discharge capacity (30%), the battery discharge voltage of Li2Na2Ti5O12 electrode than the Li4Ti5O12 negative cells higher than about 0.25V.
In summary, the structure of lithium titanate nano materials were prepared by sodium lithium ion ion substitution, substitution amount to enhance the electrochemical performance of the material, such as potential platform, discharge capacity and high rate capability. The Li2Na2Ti5O12 samples prepared with a single phase, and has low potential platform tilt, discharge capacity and good rate capability. At the same time reduce the working potential, can improve the working voltage of the lithium ion battery; commercial micron high voltage lithium nickel manganese oxide used (LiNi0.5M1.5O4) material has good electrochemical performance, the development of the Li2Na2Ti5O12 material matched with the preparation of soft packaging lithium ion battery, improve the working voltage of the lithium ion battery, which provides a new idea for the existing high performance materials R & D research and new materials of high performance.

【學(xué)位授予單位】：南開大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TM912

【參考文獻(xiàn)】

相關(guān)期刊論文 前3條

1 高鵬飛;楊軍;;鋰離子電池硅復(fù)合負(fù)極材料研究進(jìn)展[J];化學(xué)進(jìn)展;2011年Z1期

2 蔡元霸,梁玉倉;納米材料的概述、制備及其結(jié)構(gòu)表征[J];結(jié)構(gòu)化學(xué);2001年06期

3 何則強(qiáng);熊利芝;陳上;吳顯明;劉文萍;黃可龍;;Li_4Ti_5O_(12)-聚苯胺復(fù)合材料的合成與表征[J];無機(jī)化學(xué)學(xué)報(bào);2007年08期

，

本文編號：1619605