本文關(guān)鍵詞： Co_3O_4 Co_3S_4 熱處理 異質(zhì)結(jié)構(gòu) 納米陣列 鋰離子電池性能　出處：《青島大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：過渡金屬氧化物因具有較高的儲鋰容量等優(yōu)點(diǎn)而成為非常有潛力的鋰離子電池負(fù)極材料。其中,鈷基氧化物由于其高比容量和多價(jià)態(tài)等優(yōu)勢引起了人們的廣泛關(guān)注。但是,鈷基氧化物存在電導(dǎo)率低、循環(huán)穩(wěn)定性差等缺陷,因此,其尚不能應(yīng)用于市場化的鋰離子電池中。因鈷基氧化物的納米結(jié)構(gòu)對其電化學(xué)性能產(chǎn)生很大的影響,故本論文旨在通過調(diào)控其微納結(jié)構(gòu)來提高其儲鋰性能。首先,本文利用簡單的水熱法,采用硝酸鈷、氟化氨和尿素作為原料,制備出粉紅色的前驅(qū)體粉末,并通過在不同溫度下熱處理前軀體,制備出具有規(guī)則排列的Co_3O_4一維納米結(jié)構(gòu),同時(shí)研究了不同煅燒溫度對材料顆粒大小、結(jié)晶性的影響。通過XRD、SEM、Ramam等手段表征分析了其物相和納米結(jié)構(gòu),最后利用LAND電化學(xué)測試儀和電化學(xué)工作站測試了其電化學(xué)性能。通過測試,我們發(fā)現(xiàn)當(dāng)熱處理溫度為450 o C時(shí),長為60-100 nm,寬為30-40 nm的Co_3O_4納米柱有較好的結(jié)晶性,以及低的電荷轉(zhuǎn)移電阻,可以允許鋰離子更容易的進(jìn)行轉(zhuǎn)移和脫嵌,并且還擁有較好的電化學(xué)循環(huán)性能,當(dāng)循環(huán)到30圈之后,其比容量仍然能維持在805.8 m Ah g-1。其次,為了避免添加粘接劑和導(dǎo)電劑,將上述的Co_3O_4直接生長于泡沫鎳上,成功地制備出Co_3O_4@Ni納米陣列。該陣列與基底材料之間存在緊密的電化學(xué)接觸,可直接用作鋰離子電池負(fù)極。由于泡沫鎳具有三維多孔結(jié)構(gòu),Co_3O_4@Ni納由于其擁有很小的電荷轉(zhuǎn)移電阻,使得其比容量相對于粉末電極來說有了巨大的提高,其首次比容量高達(dá)2012 m Ah g-1。但是,當(dāng)循環(huán)次數(shù)達(dá)到40圈時(shí),蒲公英狀的Co_3O_4@Ni納米陣列的比容量可以維持到818 m Ah g-1,而片狀的Co_3O_4@Ni納米陣列只能維持到577 m Ah g-1。最后,為了改善上述試驗(yàn)中循環(huán)性差的問題,我們對Co_3O_4@Ni進(jìn)行表面處理。對此我們選擇的復(fù)合材料為Co_3S_4。我們對Co_3O_4@Ni納米陣列進(jìn)行硫化,得到了異質(zhì)結(jié)構(gòu)的Co_3S_4@Co_3O_4@Ni。在此之前,異質(zhì)結(jié)構(gòu)的Co_3S_4@Co_3O_4@Ni作為鋰離子電池負(fù)極材料還沒有被報(bào)道過。研究發(fā)現(xiàn),該納米結(jié)構(gòu)能較好的保持前驅(qū)體的陣列結(jié)構(gòu)。儲鋰性能結(jié)果表明,該異質(zhì)結(jié)構(gòu)具有較高的比容量和循環(huán)穩(wěn)定性,其性能更勝于單相Co_3O_4@Ni納米陣列。Co_3S_4@Co_3O_4納米陣列的首次放電比容量為1903.1 m Ah g-1,首次充電比容量仍高達(dá)1565 m Ah g-1,首次庫倫效率為82.25%。
[Abstract]:Transition metal oxides have become potential anode materials for lithium ion batteries due to their high lithium storage capacity, among which cobalt-based oxides have attracted wide attention due to their high specific capacity and multivalent state. Cobalt-based oxides have some defects such as low conductivity and poor cycling stability, so they can not be used in market-oriented lithium-ion batteries, because the nano-structure of cobalt-based oxides has a great influence on their electrochemical performance. Therefore, the aim of this thesis is to improve the lithium-storage performance by regulating its micro-nano structure. Firstly, a pink precursor powder is prepared by using simple hydrothermal method and using cobalt nitrate, ammonia fluoride and urea as raw materials. The one-dimensional Co_3O_4 nanostructures with regular arrangement were prepared by heat treatment at different temperatures, and the effects of different calcination temperatures on the particle size were studied. The effect of crystallization. The phase and nanostructure were characterized and analyzed by means of XRDX SEMN Ramam. Finally, the electrochemical properties were tested by LAND electrochemical tester and electrochemical workstation. It was found that when the heat treatment temperature was 450oC, The Co_3O_4 nanorods, which are 60-100 nm long and 30-40 nm wide, have good crystallinity and low charge transfer resistance, which allow lithium ions to transfer and deintercalate more easily, and also have better electrochemical cycling performance after 30 cycles. The specific capacity can still be maintained at 805.8 mAh g-1.Secondly, in order to avoid adding adhesive and conductive agent, the Co_3O_4 was grown directly on nickel foam. Co_3O_4@Ni nanoarrays have been successfully fabricated. There is close electrochemical contact between the array and the substrate, which can be directly used as negative electrode for lithium-ion batteries. Compared with the powder electrode, the specific capacity was greatly improved, and the first specific capacity was as high as 2012 mAh g-1.However, when the cycle times reached 40 cycles, The specific capacity of dandelion like Co_3O_4@Ni nanoarrays can be maintained up to 818 mAh g-1, while the flake Co_3O_4@Ni nanoarrays can only maintain up to 577mAh g-1.Finally, in order to improve the problem of poor circulability in the above experiments, the specific capacity of dandelion like Co_3O_4@Ni nanoarrays can be maintained up to 818 mAh g-1. We do surface treatment on Co_3O_4@Ni. For this, the composite we choose is Cos _ 3S _ 4. We vulcanized the Co_3O_4@Ni nanoarrays and got the heterostructure Co3S _ 4R _ Co _ 3O _ 4R _ (Nii). Heterostructure Co_3S_4@Co_3O_4@Ni has not been reported as a cathode material for lithium-ion batteries. It has been found that the nanostructure can keep the array structure of the precursor well. The heterostructure has high specific capacity and cyclic stability, and its performance is better than that of single-phase Co_3O_4@Ni nanoarrays. Co3S4Co3O4 nanoarrays have a first discharge specific capacity of 1903.1 mAh g-1, initial charging capacity of 1565 mAh g-1 and first Coulomb efficiency of 82.25.
【學(xué)位授予單位】：青島大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TQ138.12;TM912

【參考文獻(xiàn)】

相關(guān)期刊論文 前5條

1 邱蘭;呂洪嶺;李念武;鄭明波;曹潔明;姬廣斌;;還原氧化石墨烯/碳納米管/Co_3O_4三元復(fù)合材料的制備與電化學(xué)性能[J];化學(xué)研究;2013年02期

2 王春梅;趙海雷;王靜;王捷;呂鵬鵬;;有機(jī)物熱解碳包覆人造石墨負(fù)極材料的改性研究[J];功能材料;2012年23期

3 李昌明;趙靈智;劉志平;張仁元;李偉善;;鋰離子電池碳納米管負(fù)極材料儲鋰性能研究[J];化工新型材料;2009年06期

4 郭華軍;孫乾銘;李新海;王志興;彭文杰;;Synthesis and electrochemical performance of Co_3O_4/C composite anode for lithium ion batteries[J];Transactions of Nonferrous Metals Society of China;2009年02期

5 俞政洪,吳鋒;鋰離子電池炭負(fù)極材料的研究——包覆對天然石墨容量衰減的影響[J];新型炭材料;2002年04期

相關(guān)博士學(xué)位論文 前1條

1 謝健;某些納米銻基金屬間化合物的合成及電化學(xué)吸放鋰行為[D];浙江大學(xué);2005年

，

本文編號：1497073