(1. 中南大學(xué) 冶金與環(huán)境學(xué)院，長沙 410083；
2. 湖南城市學(xué)院 全固態(tài)儲能材料與器件湖南省重點(diǎn)實(shí)驗(yàn)室，益陽 413000；
3. 湖南華慧新能源股份有限公司，益陽413000)
摘 要: 基于COMSOL數(shù)值仿真平臺構(gòu)建鋰離子動力電池電化學(xué)-熱耦合模型，深入研究了正極材料厚度，正、負(fù)極材料顆粒半徑與電池內(nèi)部極化間的作用規(guī)律，并在此基礎(chǔ)上，歸納闡明了動力鋰離子電池放電電壓平臺衰退、放電周期驟減與電池內(nèi)部極化間的內(nèi)在關(guān)聯(lián)。結(jié)果表明：正、負(fù)極活化極化隨正極厚度的增加變化差異較大，正極活化極化在18~31 mV之間波動，而負(fù)極可達(dá)到260 mV；放電末期負(fù)極固相濃差極化急劇增加，最大值達(dá)到425 mV。正極顆粒半徑對極化的影響較小；負(fù)極顆粒半徑減小為原來的一半，即0.5Rn時放電中期的負(fù)極活化過電勢約為55 mV，較1Rn降低45%左右。負(fù)極活化極化的增加將導(dǎo)致電池放電電壓平臺下降，負(fù)極活化極化和固相濃差極化在放電末期急劇增加，是電壓提前達(dá)到放電截止電壓的最主要原因。
關(guān)鍵字: 鋰離子電池；正極厚度；顆粒半徑；固相濃差極化；活化極化
（1. School of Metallurgy and Environment, Centre South University, Changsha 410083, China;
2. Hunan Provincial Key Laboratory of All-Solid-State Energy Storage Materials and Devices, Hunan City University, Yiyang 413000, China;
3. Hunan Huahui New Energy Co., Ltd., Yiyang 413000 China）
Abstract:An electrochemical-thermal model was developed by COMSOL MULTIPHYSICS to analysis the interaction between the thickness of positive , the particle radius of positive and negative electrodes and the polarization . On this basis, the internal relations between the decline of discharge voltage platform, the sharp decrease of discharge cycle and the polarization inside the battery were summarized and illustrated. The results show that the activation polarization of the positive and negative electrodes varies significantly with the increase of the thickness of the positive electrode. The polarization of the positive electrode fluctuates between 18 mV and 31 mV, while the polarization of the negative electrode reaches 260 mV. The concentration polarization of the negative solid phase at the end of discharge increases sharply, and the maximum value reaches 425 mV. While the radius of negative electrode particles is reduced to half of original, which is 0.5Rn, the activation polarization of negative electrode at middle of discharge is about 55 mV, which is about 45% lower than 1Rn. The effect of reducing radius of positive active material particles is not obvious. The increase of activation polarization of negative is the main reason for the decline of the battery discharge voltage platform. The aggravation of activation polarization and concentration polarization of negative solid phase are the main cause of battery voltage reaching the discharge cut-off voltage in advance.
Key words: lithium ion battery; positive electrode thickness; particle radius; concentration polarization of solid ; activation polarization
