發(fā)布時間：2018-05-20 16:57

  本文選題：氫氧化鎳 + 正極材料�。� 參考：《北京有色金屬研究總院》2014年碩士論文

【摘要】：鎳氫電池是一種被廣泛使用的二次電池,已經(jīng)成為二次電池市場的主流產(chǎn)品,其具有高容量、低記憶效應、環(huán)境友好、工藝成熟和造價低廉等諸多優(yōu)點。但隨著電池技術的發(fā)展,鎳氫電池的容量成為阻礙其進一步發(fā)展的瓶頸,尤其是近年來電動汽車(EV)對于電池容量的要求日益迫切,而鎳氫電池目前尚難以滿足。因此高容量將成為鎳氫電池下一步發(fā)展過程中的關鍵技術。鎳氫電池的容量由正極和負極中容量較低的短板來決定,而目前負極容量已經(jīng)遠遠超過正極容量,提高鎳氫電池容量的瓶頸即為正極材料容量。因此研發(fā)具有高容量的正極材料具有重要的意義。 傳統(tǒng)的鎳氫電池正極為β-氫氧化鎳,經(jīng)過多年研究和改良,其放電容量逐漸迫近理論容量289mAh/g,進一步提升的空間有限,而α-氫氧化鎳由于電子轉(zhuǎn)移數(shù)較高,其理論容量高達479mAh/g,因此日益受到研究者的關注。但是其在堿性環(huán)境下結構不穩(wěn)定,會自發(fā)轉(zhuǎn)變?yōu)棣?氫氧化鎳,循環(huán)穩(wěn)定性不佳,限制了其進一步應用。 本工作在總結了相關研究的基礎上,以錳摻雜為手段,設計和合成了一種具有混合相結構的氫氧化鎳,以β相為基體提供結構穩(wěn)定性,α相為增強相提高容量,綜合α相和β相的優(yōu)缺點實現(xiàn)互補,以期得到具有優(yōu)良綜合性能的氫氧化鎳正極材料。 本工作首先系統(tǒng)的研究了混合相氫氧化鎳的合成條件,簡要討論了共沉積合成的化學環(huán)境以及后處理過程對于產(chǎn)物的影響,同時通過正交試驗和均勻設計試驗兩種不同的實驗設計方法,對于錳摻雜量、攪拌電機頻率、pH值這三項對于產(chǎn)物影響最大的因素進行了詳細的分析。試驗結果表明,錳摻雜量宜保持在10%-15%之間,過低的錳摻雜量無法有效地提高樣品的放電容量,而過高的錳摻雜量則有可能導致氫氧化鎳結構損傷,劣化電極性能。攪拌電機頻率宜保持在30Hz左右,過低的攪拌電機頻率不利于Mn2+離子的氧化,從而導致α相含量偏低；過高的攪拌電機頻率則不利于金屬離子的共沉積,導致結晶狀況劣化。pH值則在試驗范圍內(nèi)越高越有利于放電容量的提高,原因在于高pH值條件下的沉積有利于晶體缺陷的生成,從而提高氫氧化鎳的充放電效率。 為了進一步研究錳摻雜混合相氫氧化鎳的形成機制和實際使用性能,本工作通過合成不同錳摻雜含量的氫氧化鎳并對其進行物理化學表征,詳細探究了錳摻雜量對氫氧化鎳樣品的影響。結果顯示,隨著錳摻雜量的不斷提高,氫氧化鎳的晶體結構由β相逐漸轉(zhuǎn)變?yōu)棣料?在這一轉(zhuǎn)變過程中出現(xiàn)了符合本實驗設計的混合相氫氧化鎳結構。同時隨著錳摻雜量的提高,嵌入氫氧化鎳層間的陰離子和水分子的數(shù)量也顯著增多,這些嵌入粒子一方面通過擴大層間間距誘導了α相的生成,另一方面擴大的層間間距又反過來使得更多的粒子可以嵌入層間。因此層間間距的擴大與嵌入粒子的數(shù)量增多互相作用,共同誘導了氫氧化鎳的相轉(zhuǎn)變行為。通過對合成樣品的形貌分析可以看到,樣品在掃描電子顯微鏡下具有獨特的蜂窩狀微觀形貌,其有利于提高氫氧化鎳樣品的充放電效率。合成樣品的電化學性能測試表明,符合本實驗設計結構的混合相氫氧化鎳在0.2C充放電速率下不僅放電容量達到了330mAh/g,相比普通商用p-氫氧化鎳提高約16%,同時在充放電循環(huán)中保持了良好的結構穩(wěn)定性,50次循環(huán)后容量沒有出現(xiàn)衰減現(xiàn)象。 為了滿足電動汽車大功率動力電池的需要,本工作進一步對合成的混合相氫氧化鎳做了覆鈷處理,結果顯示包覆鉆氧化物樣品的粉末電阻明顯降低,電性能測試顯示盡管在0.2C下放電容量有一定衰減,但是在1C大電流充放電時相比未覆鈷樣品容量有較為明顯提升,因此其有望作為一種大功率高容量正極材料得到應用。
[Abstract]:Ni MH battery is a widely used two battery. It has become the mainstream product in the two battery market. It has many advantages, such as high capacity, low memory effect, friendly environment, mature technology and low cost. But with the development of battery technology, the capacity of Ni MH battery has become a bottleneck that hinders its further development, especially in recent years. Electric vehicle (EV) is becoming more and more urgent for battery capacity, and Ni MH battery is still difficult to meet at present. Therefore, high capacity will be the key technology in the next development process of Ni MH battery. The bottleneck of the capacity of high nickel hydrogen battery is the capacity of cathode material. Therefore, developing high capacity cathode materials is of great significance.
The traditional nickel hydrogen battery positive electrode is beta - nickel hydroxide. After years of research and improvement, the discharge capacity is gradually approaching the theoretical capacity of 289mAh/g, and the space for further upgrading is limited, while the theoretical capacity of the alpha hydroxide nickel hydroxide is up to 479mAh/g because of the high electron transfer number, so it is increasingly concerned by the researchers. But the structure is in the alkaline environment. Instability will change spontaneously into beta nickel hydroxide, and its poor stability will limit its further application.
On the basis of the related research, a kind of nickel hydroxide with mixed phase structure is designed and synthesized with manganese doping as a method. The structure stability is provided with beta phase as the matrix, the alpha phase is enhanced to enhance the capacity and the advantages and disadvantages of the synthesis of alpha and beta phase are complementation, in order to obtain good comprehensive properties of nickel hydroxide. Material Science.
This work first systematically studied the synthesis conditions of the mixed phase nickel hydroxide, briefly discussed the chemical environment of the co deposition and the effect of the post-treatment process on the product. At the same time, two different experimental design methods, through orthogonal test and uniform design test, were used for the three items of manganese mixing, stirring motor frequency, and pH value. The test results show that the amount of manganese doping should be kept between 10%-15% and the low manganese doping amount can not effectively improve the discharge capacity of the sample, while the excessive manganese doping may lead to the damage of the nickel hydroxide structure and the deterioration of the electric polarity. The frequency of the stirred motor should be kept around 30Hz. The low frequency of the stirred motor is not conducive to the oxidation of Mn2+ ions, which leads to the low content of the alpha phase, and the high frequency of stirred motor is not conducive to the co deposition of metal ions. The higher the crystallization condition, the higher the.PH value in the test range is beneficial to the increase of discharge capacity. The reason is that the deposition of high pH is beneficial to the lack of crystal. Thus, the charge and discharge efficiency of nickel hydroxide is improved.
In order to further study the formation mechanism and practical performance of Mn doped nickel hydroxide, the physical and chemical characterization of nickel hydroxide with different manganese content was synthesized and the effect of manganese doping on the sample of nickel hydroxide was investigated in detail. The crystal structure is gradually transformed from beta phase to alpha phase. In the process of this transformation, the structure of the mixed phase nickel hydroxide which is in accordance with the experimental design has appeared. With the increase of manganese doping, the number of anions and water molecules embedded in the layer of nickel hydroxide increased significantly. These embedded particles have induced the alpha phase by expanding the interlayer space. The expansion of interlayer space on the other hand, in turn, makes more particles embedded in the interlayer. Therefore, the expansion of the interlayer space and the number of embedded particles interact with each other, which co induces the phase transition behavior of nickel hydroxide. The unique honeycomb micro morphology is beneficial to improve the charge discharge efficiency of the nickel hydroxide sample. The electrochemical performance test of the synthesized sample shows that the discharge capacity of the mixed phase nickel hydroxide conforming to the design structure is 330mAh/g at the charge discharge rate of 0.2C, and is about 16% higher than that of the ordinary commercial p- nickel hydroxide. The discharge cycle keeps good structural stability, and the capacity does not decay after 50 cycles.
In order to meet the needs of the high-power power battery of the electric vehicle, the composite phase of the mixed phase nickel hydroxide was further treated with cobalt treatment. The results showed that the powder resistance of the coated oxide sample was obviously reduced. The electrical performance test showed that although the discharge capacity was attenuated under the 0.2C, it was compared with the 1C when the high current charge and discharge were not covered. The cobalt sample capacity has been significantly improved, so it is expected to be used as a high-power, high capacity cathode material.
【學位授予單位】：北京有色金屬研究總院
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM912

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本文編號：1915481