(1. 哈爾濱工業(yè)大學(xué)(威海) 應(yīng)用化學(xué)系，威海 264209；
2. 松山湖材料實驗室，東莞 523808)
摘 要: 單晶型正極材料因其高循環(huán)性和高壓實密度，已成為目前最有應(yīng)用前景的材料之一。單晶材料是對二次球形顆粒的改進，了解單晶的形成和循環(huán)機制對單晶的制備有著很好的指導(dǎo)作用。本文首先分析了單晶材料的結(jié)構(gòu)特征，單晶氧化物與球形二次顆粒氧化物都是層狀結(jié)構(gòu)；接著闡述了單晶的穩(wěn)定性機理，單晶無內(nèi)部晶界，在循環(huán)過程中不存在晶間破碎。本文還對單晶的形成和循環(huán)失效機理進行了總結(jié)，重點闡述單晶型正極材料在合成過程中溶解-再結(jié)晶的形成機理，即二次顆粒前驅(qū)體崩解，一次顆粒慢慢長大形成單晶顆粒；在循環(huán)過程中當截止電壓小于4.3V時，晶內(nèi)層間滑移可逆，多次充放電后存在滑移痕跡；當截止電壓大于4.3V時，多次循環(huán)后出現(xiàn)晶內(nèi)斷裂，電池性能下降。
關(guān)鍵字: 鋰離子電池；單晶；形成機理；失效機理；三元材料
（1. Department of Applied Chemistry, Harbin Institute of Technology, Weihai 264209, China;
2. Songshan Lake Materials Laboratory, Dongguan 523808, China）
Abstract:Single crystal cathode materials have become one of the most promising materials due to their high cycling and high pressure density. Single crystal material is an improvement on secondary spherical particles. Understanding the formation and cycling mechanism of single crystal has a good guiding role in the preparation of single crystal. In this paper, the structural characteristics of single crystal materials were firstly analyzed. Both single crystal oxides and spherical secondary particle oxides have layered structures. Then, the stability mechanism of single crystal was described. Single crystal has no internal grain boundary and there is no intercrystal breakage during the cycle. In this paper, the formation and cyclic failure mechanism of single crystal cathode materials were summarized. In addition, the formation mechanism of dissolution and recrystallization of the secondary particle precursor disintegrating and the primary particle gradually growing into the single crystal particle during the synthesis process of the single crystal cathode material was emphasized. When the cutoff voltage is less than 4.3 V, the slippage is reversible and there are slippage traces after multiple charging and discharging. When the cutoff voltage is greater than 4.3 V, the intragranular fracture occurs after several cycles and the battery performance deteriorates.
Key words: lithium-ion battery; single-crystal; formation mechanism; failure mechanism; ternary materials
