Ammonia- and lithia-doped manganese dioxide for 3 V lithium batteries.
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{center_dot}0.007NH{sub 3}]{center_dot}MnO{sub 2} gave the best electrochemical performance in liquid organic electrolyte (1:1 EC:DMC, 1 M 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 O{sup 2-} from the 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.
- Research Organization:
- Argonne National Laboratory (ANL)
- Sponsoring Organization:
- SC
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 949241
- Report Number(s):
- ANL/CMT/JA-38977
- Journal Information:
- J. Power Sources, Journal Name: J. Power Sources Journal Issue: Jul. 2001 Vol. 97-8; ISSN JPSODZ; ISSN 0378-7753
- Country of Publication:
- United States
- Language:
- ENGLISH
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