CoO{sub 2}, the end member of the Li{sub x}CoO{sub 2} solid solution
- Bellcore, Red Bank, NJ (United States)
- Rutgers, The State Univ. of New Jersey, Piscataway, NJ (United States)
While LiCoO{sub 2} has been widely studied in the past 15 years as a promising positive electrode material in lithium-ion batteries, surprisingly, many questions are still unanswered concerning the electrochemical characteristics of the lithium intercalation material. Among these is the existence of an end member CoO{sub 2} phase on complete lithium deintercalation. The use of dry plastic lithium-ion battery technology has allowed the construction of an in situ X-ray diffraction cell which allows structural characterization of Li{sub x}CoO{sub 2} at x values at and close to 0 for the first time. Instead of the expected destruction of the core structure of LiCoO{sub 2} by a drastic increase in structural disorder, an increase in crystallographic quality occurred as x approached 0. For the first time, the end member CoO{sub 2} phase was isolated. This phase is a hexagonal single-layered phase (O1) believed to be isostructural with CdI{sub 2} and has lattice parameters of a = 2.822 {angstrom} and c = 4.29 {angstrom}. The phase converted immediately back to a three-layer (O3) delithiated Li{sub x}CoO{sub 2} type phase on lithium reinsertion. Electrochemical studies show that 95% of lithium can be reinserted back into the structure on complete delithiation and reversible cycling properties are maintained when cycled back to 4.2 V.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 220888
- Journal Information:
- Journal of the Electrochemical Society, Vol. 143, Issue 3; Other Information: PBD: Mar 1996
- Country of Publication:
- United States
- Language:
- English
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