(中南大學(xué) 化學(xué)化工學(xué)院， 長(zhǎng)沙 410083)
摘 要: 介紹了一種以容量參數(shù)為主變量的測(cè)定鋰二次電池中電極材料固相擴(kuò)散系數(shù)的方法。 該方法只需顆粒半徑這一輔助參數(shù)， 通過球型擴(kuò)散模型建立了恒流-恒壓充電容量(RPG)比， 進(jìn)一步發(fā)展成為容量間歇滴定技術(shù)(CITT)。 采用RPG法可在較寬的電壓范圍內(nèi)測(cè)定嵌入型電極材料的平均固相擴(kuò)散系數(shù)， 實(shí)驗(yàn)結(jié)果重現(xiàn)性好。 由RPG法測(cè)得0～1.5 V時(shí)鋰離子在石墨電極中的平均固相擴(kuò)散系數(shù)值為1.055×10-10cm2/s。 由CITT技術(shù)測(cè)得鋰離子在LiMn2O4中的固相擴(kuò)散系數(shù)在3.95 V和4.12 V左右存在個(gè)兩個(gè)極小峰， 且隨著循環(huán)次數(shù)的增加， 擴(kuò)散系數(shù)值逐漸增大。
關(guān)鍵字: 固相擴(kuò)散系數(shù)； 容量參數(shù)； 嵌入型電極材料； 鋰二次電池
（College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China）
Abstract: A method of determining the solid diffusion coefficient of electrode materials in the lithium battery was introduced, where the capacity was the main variable. This method needs only one complementary parameter ( the radius of insertion-host particle, R) . Based on the ratio of potentio-charge capacity to the galvano-charge capacity(RPG) by the spherical diffusion model, the method was developed to the capacity intermittent titration technique(CITT). By RPG method, the average solid diffusion coefficient of insertion-host materials can be determined at a relativly wide range of voltage. The Li+ diffusion coefficients in graphite were determined as 1.055×10-10cm2/s in the voltage range from 0 to 1.5V. The Li+ solid diffusion coefficients in LiMn2O4 were determined at different galvano-charge currents. Results shows that the Li+ solid diffusion coefficients reach the minimum at the voltage of 3.95 and 4.12 V, and the diffusion coefficients increase with the increasing circulation times. So by CITT method, the solid diffusion coefficient of electrode materials at different charge-discharge circulations can be determined conveniencely.
Key words: solid diffusion coefficient; capacity parameter; insertion-host electrode materials; secondary lithium battery
