(1. 有研科技集團有限公司，國家動力電池創(chuàng)新中心，北京 100088；
2. 北京有色金屬研究總院，北京 100088；
3. 寧德時代新能源科技股份有限公司，寧德 352100)
摘 要: 本文以鈷酸鋰正極材料為例，采用熱重-質(zhì)譜聯(lián)用技術(shù)(TG-MS)，分析了正極材料的熱分解及其與電解液的反應(yīng)熱特性，考察了不同充電態(tài)、電解液對層狀正極材料熱穩(wěn)定性的影響，并系統(tǒng)分析了O2增加的原因。結(jié)果表明：隨著充電截止電壓的增加，鈷酸鋰的脫鋰量增大，層狀結(jié)構(gòu)破壞程度加劇，熱分解釋放出更多的O2。對比了4.4 V的LiNi0.33Mn0.33Co0.33O2(4.4 V-NMC111)和4.2 V的LiNi0.8Mn0.1Co0.1O2(4.2 V-NMC811)正極材料熱穩(wěn)定性，并明確以4.4 V-NMC111與4.2 V-NMC811為陰極制作的全電池具有相近的能量密度，但4.4 V-NMC111電池表現(xiàn)出更好的耐高溫性。
關(guān)鍵字: 鋰離子電池；正極材料；高電壓；熱穩(wěn)定性；熱重-質(zhì)譜聯(lián)用技術(shù)
（1. National Automotive Cell Innovation Center, GRINM Group Co., Ltd., Beijing 100088, China;
2. General Research Institute for Nonferrous Metals, Beijing 100088, China;
3. Contemporary Amperex Technology Co., Ltd., Ningde 352100, China）
Abstract:The thermogravimetry-mass spectrometry (TG-MS) technique was used to analyze the thermal stability of cathode materials, including the thermal decomposition, the reaction thermal characteristics with the electrolyte, and the effects of different states of charge and electrolyte. For the lithium cobaltate cathode material, the reason why the O2 increased in LixCoO2 was systematically explored. The results show that the layered structure of the cathode materials is broken with the cut-off voltage increasing, resulting in the thermal stability decreasing, and even the thermal decomposition to release more oxygen with the increase of the amount of delithiation. Comparing the thermal stability of the cathode material of the full battery based on the 4.4 V LiNi0.33Mn0.33Co0.33O2 (4.4 V-NMC111) and 4.2 V LiNi0.8Mn0.1Co0.1O2 (4.2 V-NMC811), it is demonstrated that despite the similar energy density of 4.4 V-NMC111 and 4.2 V-NMC811, the 4.4 V-NMC111 has better high temperature resistance performance.
Key words: lithium ion battery; cathode materials; high voltage; thermal stability; thermogravimetry-mass spectrometry technique
