3 V manganese oxide electrode materials for lithium batteries.

Johnson, C. S. ; Thackeray, M. M.

Technical Information Center Oak Ridge Tennessee

关键词: Electrodes;    Lithium batteries;    Voltametry;    Manganese oxides;    Metal-nonmetal batteries;   

RP-ID  :  DE2001757555

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

Specific discharge capacities in excess of 200 mAh/g and good reversible cycling behavior between 3.8 and 2.0 V has been observed in a lithium cell for alpha-MnO(sub 2) phases with the hollandite structure. A combination of lithia (Li(sub 2)O) doping and ammonia (NH(sub 3)) treatment of the active material powder having the composition alpha-(0.143LI(sub 2)O). (0.007 NH(sub 3)) MnO(sub 2) gave the best electrochemical performance in liquid organic electrolytee (1:1 EC:DMC, 1M LiPF(sub 6)) coin cells, with metallic Li as the negative electrode. The added lithia forms a defect close-packed array of oxide anions and stabilizes the interior of the 2x2 tunnel of the hollandite structure by partially filling the crystallographic position (0,0,0.5) of the tetragonal unit cell (I4/m) with 0(sup 2) from the I added Li(sub 2)O. Ammonia treatment is hypothesized to partially fill other lattice vacancies still available within the 2x2 tunnel with the nitrogen atoms from NH(sub 3) taking the same position as the oxide anion in the array. The NH(sub 3) can further stabilize the cell during lithium insertion/extraction because of its favorable hydrogen bonding ability and Lewis base characteristics.