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本文利用电化学方法测定了薄膜电极Li_xTiO_2中锂离子的化学扩散系数,室温下其数量级为10~(-11)～10~(-12)cm~2·S~(-1)(x=0.10～0.20)。通过D_4-T关系,测得其扩散激活能E(?)0.59eV,频率因子D_0(?)O.54cm~2·s~(-1).故其一般式可表为:D_4=O.54exp(-6785/T)cm~2·s~(-1)(t=15～50℃).利用D_4值和库仑滴定曲线测得了Li~+在Li_xTiO_2薄膜电极中的迁移率和电导率分别为10~(-10)cm~2·V~(-1)·s~(-1)和10~(-7)～10~(-8)Ω~(-1)·cm~(-1)数量级。比较了Li_xTiO_2体系与其他锂嵌入物的D_4值,发现其与隧道化合物Li_xWO_3的D_4值相近,而比层状化合物Li_xTiS_2的D_4值小3～4个数量级。D_4值较大的嵌入物在作为锂电池的正极时,可以经受较大的充放电流。
In this paper, the electrochemical diffusion coefficient of Li-xTiO_2 in Li_xTiO_2 thin film electrode was measured by electrochemical method. The results show that the lithium ion diffusion coefficient is about 10 ~ (-11) ~ 10 ~ (-12) cm ~ 2 · S ~ (-1) ~ 0.20). The diffusion activation energy E (?) 0.59eV and the frequency factor D0 (?) O.54cm ~ 2 · s ~ (-1) were measured by the D_4-T relationship, so the general formula is: D_4 = O. 54exp (-6785 / T) cm ~ 2 · s ~ (-1) (t = 15 ~ 50 ℃) .The mobility and conductivity of Li ~ + in Li_xTiO_2 thin film electrode were measured by D_4 and Coulometric titration curves respectively The results were as follows: 10 ~ (-10) cm ~ 2 · V -1 s -1 and 10 -7 -10 ~ -8 Ω -1 cm -1 )Magnitude. The D_4 values of Li_xTiO_2 system and other lithium intercalation compounds were compared and found to be close to the D_4 value of the Li_xWO_3 tunneling compound and 3-4 orders of magnitude smaller than that of the Li_xTiS_2 layered compound. Inserts with larger D_4 values can withstand larger charge and discharge currents when used as the positive electrode of lithium batteries.