發(fā)布時間：2018-01-14 12:29

  本文關(guān)鍵詞：鈦酸鑭鈉基陶瓷電解質(zhì)制備與電學(xué)性能研究　出處：《中國地質(zhì)大學(xué)》2017年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 鈉離子陶瓷電解質(zhì) NLTO基陶瓷 摻雜改性 晶體結(jié)構(gòu) 離子電導(dǎo)率

【摘要】：無論是在移動電腦、智能手機中,還是在電動汽車和混合動力汽車中,電池作為核心的儲能器件,已經(jīng)成為信息社會人們?nèi)粘Ｉ钪胁豢苫蛉钡囊徊糠�。與傳統(tǒng)的鋰離子電池相比,鈉離子電池有原料資源豐富、成本低廉、分布廣泛,可分解電勢更低的電解質(zhì)溶劑或電解質(zhì)鹽和相對穩(wěn)定的電化學(xué)性能,從而使得其具有更為突出的使用價值。因此,鈉離子電池是目前所使用鋰離子電池的最佳替代品。然而,由于電池在使用過程中存在電解液易燃與泄露造成嚴(yán)重的安全隱患,因此開發(fā)無機固態(tài)鈉離子電解質(zhì)是當(dāng)下解決電池安全問題的重要策略之一。在開發(fā)無機固態(tài)鈉離子電解質(zhì)的過程中發(fā)現(xiàn):傳統(tǒng)利用高溫固相法合成電解質(zhì)陶瓷容易產(chǎn)生雜相,且合成的粉體容易燒結(jié)、粒度分布廣等降低其電性能的缺點。此外,由于鈉離子半徑過大,使得Na_(0.5)La_(0.5)TiO_3(NLTO)陶瓷電解質(zhì)中存在鈉離子在晶體結(jié)構(gòu)中不易遷移,從而造成低離子電導(dǎo)率的弊端。針對以上問題,本論文主要是通過開發(fā)一種新型合成鈣鈦礦結(jié)構(gòu)NLTO陶瓷電解質(zhì)材料的方法,系統(tǒng)探究了合成條件對陶瓷電解質(zhì)離子電導(dǎo)率的影響,確定NLTO陶瓷最佳制備工藝。然后,在此基礎(chǔ)上對NLTO陶瓷進行A、B位摻雜改性,并探究了NLTO陶瓷晶粒晶界結(jié)構(gòu)、物相組成、晶胞參數(shù)等的變化對NLTO陶瓷中Na離子遷移的影響機制。結(jié)果發(fā)現(xiàn)制備工藝及元素?fù)诫s均對NLTO陶瓷離子電導(dǎo)率有顯著的影響。以下是本論文所得到的初步結(jié)果:(1)本文通過共離子絡(luò)合法成功制備出純相鈣鈦礦結(jié)構(gòu)的NLTO納米粉體。與傳統(tǒng)的固相法相比,本方法具備合成溫度低、制備的樣品純度高、樣品粒度分布均勻等優(yōu)點。此外,將所得粉體進一步制成電解質(zhì)陶瓷薄片,系統(tǒng)探究燒結(jié)工藝對其離子電導(dǎo)率影響。結(jié)果發(fā)現(xiàn),在一定范圍內(nèi),提高煅燒溫度,延長煅燒時間對NLTO陶瓷晶粒晶界結(jié)構(gòu)有明顯的改善作用,并最終確定煅燒溫度為1200 oC、煅燒時間為12 h時可獲得晶粒尺寸為650 nm、相對致密度為74.7%的NLTO基陶瓷。此時,其具有最佳離子電導(dǎo)率為1.01x10-5 S cm~(-1)與文獻中報道提高了近2個數(shù)量級。(2)在成功制備NLTO陶瓷電解質(zhì)基礎(chǔ)上,為了進一步解決由鈉離子半徑過大引起離子遷移困難,造成NLTO陶瓷電解質(zhì)離子電導(dǎo)率較低的問題,本文設(shè)計了系列摻雜改性實驗。首先在A位摻雜Al、Fe、Mg、Cu四種元素。由于這四種元素原子半徑較小,在NLTO陶瓷中形成間隙摻雜。在一定的摻量范圍內(nèi),這四種元素均有利于改善NLTO陶瓷的晶粒晶界結(jié)構(gòu),提高陶瓷的致密度。其中Mg、Cu元素還有利于在陶瓷與電極之間形成離子“過渡區(qū)”,這種離子“過渡區(qū)”有利于減小陶瓷界面電阻,從而提高其離子電導(dǎo)率。本文還系統(tǒng)探究了不同摻量對NLTO陶瓷離子電導(dǎo)率的影響,結(jié)果發(fā)現(xiàn)當(dāng)Al摻量為0.15時,NLTO陶瓷致密度最高可達(dá)96%,總離子電導(dǎo)率為4.54x10-5 S cm~(-1);Cu摻量為0.15時,NLTO陶瓷致密度最高可達(dá)95.8%,總離子電導(dǎo)率最高為1.24×10-4 S cm~(-1)。較NLTO陶瓷電解質(zhì)原樣離子電導(dǎo)率有明顯的提高。(3)進一步在A位摻雜原子半徑較大的Ca、Ba元素,通過XRD分析發(fā)現(xiàn),摻雜這2種元素使得NLTO陶瓷原本的特征衍射峰發(fā)生偏移,說明Ca、Ba元素與La元素形成替代摻雜。并且,摻雜Ca元素使得衍射峰向高角度偏移,說明NLTO陶瓷晶胞參數(shù)減小,從而使得鈉離子遷移通道變窄,因而其離子電導(dǎo)率會降低;摻雜Ba元素時,使得衍射峰向低角度偏移,利于擴大NLTO基陶瓷晶胞參數(shù),拓寬Na離子遷移通道,提升其離子電導(dǎo)率。說明摻雜大原子半徑有利于優(yōu)化NLTO陶瓷晶體結(jié)構(gòu),改善其離子遷移通道。當(dāng)Ba摻量為0.2時可得到最佳離子電導(dǎo)率為3.21×10-5 S cm~(-1)。在上述A位單摻研究基礎(chǔ)上結(jié)合Ba、Cu元素?fù)诫s的優(yōu)勢,得到Na_(0.5)La_(0.37)Cu_(0.1)Ba_(0.1)TiO_3(NLBUTO)共摻型陶瓷。對NLBUTO陶瓷進行元素分布,XPS、Raman等分析,發(fā)現(xiàn)摻雜Ba、Cu同時繼承了Ba元素調(diào)控其晶體結(jié)構(gòu)和Cu元素改善其晶粒晶界結(jié)構(gòu)的優(yōu)勢,使得NLBUTO致密度達(dá)到93.5%,同時其離子電導(dǎo)率增大到1.76×10-4 S cm~(-1),是目前得到最高離子電導(dǎo)率。(4)研究表明B位摻雜有利于調(diào)控鈣鈦礦結(jié)構(gòu)中Ti-O八面體的體積和偏轉(zhuǎn),從而調(diào)控鈉離子遷移通道。本文在NLTO基陶瓷的基礎(chǔ)上,分別制備了Zr、Ce等B位摻雜NLTO基納米粉體和Na_(0.5)La_(0.5)Ti_(1-x)Zr_xO_3(NLTZO,0.02≤x≤0.1)、Na_(0.5)La_(0.5)Ti_(1-x)Ce_xO_3(NLTCO,0.1≤x≤1.0)等NLTO基陶瓷。結(jié)果發(fā)現(xiàn),摻雜Zr元素含量在0.1以內(nèi)時,能保持NLTO陶瓷原本的立方相鈣鈦礦結(jié)構(gòu),且其晶胞參數(shù)隨著摻量增大而增大,因此其Na離子遷移通道得到拓展,從而其離子電導(dǎo)率得到提高。當(dāng)Zr摻量為0.08時有最高離子電導(dǎo)率為4.08×10-5 S cm~(-1)。而摻入不同含量Ce元素后,NLTO陶瓷原始的立方相會發(fā)生變化,并且形成CeO_2和四方相NLTO兩種新物相。新物相的形成對NLTO陶瓷的晶粒晶界結(jié)構(gòu)、物相組成有顯著的影響。隨著摻量的變化,所得樣品中CeO_2、NLTOT、NLTOC三種物相的相對含量也發(fā)生變化。當(dāng)摻量為0.7時,其三者相對含量比例為3:2:20有最佳離子電導(dǎo)率為2.67×10-5 S cm~(-1)。綜上,本文以NLTO陶瓷電解質(zhì)材料為研究對象,首先通過開發(fā)一種新型合成方法制備得到高質(zhì)量的NLTO納米粉體,然后系統(tǒng)探究制備NLTO陶瓷電解質(zhì)的制備工藝,確定最佳合成條件。在得到NLTO陶瓷電解質(zhì)的基礎(chǔ)上,通過摻雜技術(shù),對NLTO陶瓷晶粒晶界結(jié)構(gòu)、物相組成、晶體結(jié)構(gòu)進行優(yōu)化,得到具有最佳離子電導(dǎo)率(1.76×10-4 S cm~(-1))的NLTO陶瓷電解質(zhì)材料,該離子電導(dǎo)率是目前同類材料中報道最高。此外,本文系統(tǒng)研究了不同元素不同位置摻雜NLTO基陶瓷對其離子電導(dǎo)率的影響規(guī)律,可以為研究其它在無機固態(tài)鈉離子電解質(zhì)材料提供有價值的參考。
[Abstract]:Whether it is in the mobile computer, intelligent mobile phone, or in the electric and hybrid vehicles, battery energy storage device as the core, has become an integral part of the information society in people's daily life. Compared with the traditional lithium ion batteries, sodium ion batteries have abundant raw material resources, low cost, wide distribution, can lower decomposition potential of electrolyte solvent or electrolyte and the electrochemical performance is relatively stable, so that it has more prominent value. Therefore, the sodium ion battery is the best alternative to the use of lithium ion batteries. However, because the battery is in use in the process of flammable and electrolyte leakage caused by serious hidden troubles. Therefore the development of inorganic solid electrolyte sodium ion is one of the important strategies to solve the battery safety issues. Found in the development of inorganic solid electrolyte of sodium ion in the process: Based on the traditional high temperature solid phase synthesis method to produce ceramic electrolyte impurity phase, and the powder synthesized by easy sintering, particle size distribution etc. reduce the electrical properties of faults. In addition, the sodium ion radius is too large, the Na_ (0.5) La_ (0.5) TiO_3 (NLTO) ceramic electrolyte in the sodium ion in the crystal structure not easy to transfer, resulting in defects of low ionic conductivity. To solve the above problems, this paper is mainly through the development of a new synthesis method of NLTO perovskite ceramic electrolyte materials, to explore the synthesis conditions on the conductivity of ceramic electrolyte from the impact, to determine the best preparation process of NLTO ceramic. Then, on the basis of NLTO ceramic A, modification of B doping, and to explore the NLTO ceramic grain boundary structure, phase composition, change of lattice parameters on the influence mechanism of Na ion migration in NLTO ceramics. The results showed that the process and preparation All dopants have significant influence on the ionic conductivity of NLTO ceramics. The following is the preliminary results of this thesis are: (1) the total ion complexation prepared NLTO nano powders of pure perovskite structure. Compared with the traditional solid phase method, this method has low synthesis temperature, sample purity the preparation of high, the advantages of uniform size distribution of samples. In addition, the resulting powder made further electrolyte ceramic sheets, explore the effect of sintering process on the ionic conductivity of the system. The results showed that in a certain range, the increase of calcination temperature, calcination time prolonging has obvious improvement effect on NLTO ceramic grain boundary structure, and ultimately determine the calcination the temperature is 1200 oC, calcination time for grain size can be obtained for 650 nm and 12 h, the relative density of NLTO based ceramics 74.7%. At this time, it has the best ionic conductivity of 1.01x10-5 S cm ~ (-1) and Literature Reported increased by nearly 2 orders of magnitude. (2) in the preparation of NLTO ceramic electrolyte on the basis, in order to further solve the difficulties caused by ion migration by sodium ion radius, resulting in NLTO ceramic electrolyte ionic conductivity is low, this paper designs a series of doping experiments. Firstly, A doped Al Fe, Mg, Cu four elements. Because the four elements of the atomic radius is smaller, the formation of gap doping in NLTO ceramics. In a certain range of dosage, the four elements are beneficial to improve the grain boundary structure of NLTO ceramics, improve the density of ceramics. The Mg, Cu elements are conducive to the formation of the ion "transition zone" between the ceramic and electrode, the ion "transition zone" is beneficial to reduce the ceramic interface resistance, so as to improve the ionic conductivity system. This paper also explores the effects of different dosage on the ionic conductivity of NLTO ceramics, the results showed that when Al When the amount is 0.15, NLTO density of up to 96%, the total ionic conductivity of 4.54x10-5 S cm~ (-1); the content of Cu is 0.15, NLTO density of up to 95.8%, the total ionic conductivity up to 1.24 x 10-4 S cm~ (-1). Compared with NLTO ceramic electrolyte ion conductivity is obvious improved. (3) further doped with A larger atomic radius Ca, Ba element analysis by XRD shows that the doping of these 2 elements make NLTO ceramic characteristic diffraction peak of the original shift, Ca, Ba and La elements to form substitutional doping and doping Ca element makes the diffraction peaks shift to the high angle, indicating reduced NLTO ceramic cell parameters, so that the sodium ion transport channel narrows, and the ionic conductivity decreases; Ba doping, the diffraction peak shifts to the low angle, conducive to the expansion of NLTO based ceramic cell parameters, broadening the Na ion migration channel, enhance its The ionic conductivity of doped. Large atomic radius is optimized for the NLTO ceramic crystal structure, improve the ion migration channel. When the dosage of Ba is 0.2 can get the best ionic conductivity is 3.21 * 10-5 S cm~ (-1). The A based on single doped with Ba, the advantages of Cu doping, get Na_ (0.5) La_ (0.37) Cu_ (0.1) Ba_ (0.1) TiO_3 (NLBUTO) Co doped ceramics. On NLBUTO ceramic element distribution, XPS, Raman analysis, found that the doping of Ba, Cu and Ba elements inherit the regulation of its crystal structure and Cu elements to improve its grain boundary structure advantages, making the the density of NLBUTO reached 93.5%, while the ionic conductivity increases to 1.76 * 10-4 S cm~ (-1), is currently the highest ionic conductivity. (4) study shows that B doped with volume and deflection for Ti-O regulation of the perovskite structure with eight sides, thereby regulating the sodium ion transport channel in the NLTO based ceramic. 鐡風(fēng)殑鍩虹涓，

本文編號：1423598