量子化學(xué)DV-Xα研究
( 1. 重慶大學(xué) 化學(xué)化工學(xué)院， 重慶 400044;
2. 重慶師范大學(xué) 化學(xué)系， 重慶 400047)
摘 要: 采用原子基表示的第一原理贗勢DV-Xα方法， 計(jì)算了鋰離子電池正極材料LixMn2O4(x=0, 1, 2)各種模型的電子結(jié)構(gòu)。 結(jié)果表明： 電極材料LixMn2O4具有較好的電子導(dǎo)電性， 鋰離子嵌入正極材料后發(fā)生Jahn-Teller效應(yīng)引起材料結(jié)構(gòu)改變； 鋰離子的凈電荷變?yōu)?0.7（x=1）、 +0.9或+0.5（x=2）， 說明鋰離子過度嵌入LixMn2O4中， 導(dǎo)致部分鋰離子和氧離子的相互作用增強(qiáng)， 鋰離子脫出較為困難， 從而容量降低。 最高占有軌道(HOMO)到最低空軌道(LUMO)的躍遷能很小， 電子較易進(jìn)行嵌入和脫出。
關(guān)鍵字: 鋰離子電池; LixMn2O4; 量子化學(xué)DV-Xα方法
electrode material LixMn2O4 for lithium ion battery
（ 1. College of Chemistry and Chemical Engineering,
Chongqing University,Chongqing 400044, China;
2. Department of Chemistry, Chongqing Normal University, Chongqing 400047, China）
Abstract: By employing the “atomic-basis+norm-conserving non-local pseudopotential” first principle quantum chemical DV-Xα method, the electronic structure of electrode materials LixMn2O4 (x=0, 1, 2) for lithium ion battery was studied. The calculating results show that all these three materials have good electronic conductivity, and the Jahn-Teller distortion and the change of structure in the electrode material after intercalation of lithium ion. The net charge of lithium ion is +0.7, +0.9 and +0.5 when x is 1 and 2, respectively. This indicates that the interactions between lithium ion and oxygen ion are increased for the excessive intercalation of lithium ion, so the deintercalation of lithium ion becomes more difficult and the reversible capacity of the electrode is decreased. While the electron intercalates and deintercalates easily due to the smaller energy that orbit leaps from the HOMO orbit to the LUMO orbit.
Key words: lithium ion battery; LixMn2O4; quantum chemical DV-Xα method
