The role of Li{sub 2}MO{sub 2} structures (m = metal) in the electrochemistry of (chi)LiMn{sub 0.5}Ni{sub 0.5}O{sub 2} {center_dot} (1 - chi)Li(sub 2}TiO{sub 3} electrodes for lithium-ion batteries.
The electrochemical reactions of lithium with layered composite electrodes ({chi})LiMn{sub 0.5}Ni{sub 0.5}O{sub 2} {center_dot} (1 - {chi})Li{sub 2}TiO{sub 3} were investigated at low voltages. The metal oxide 0.95LiMn{sub 0.5}Ni{sub 0.5}O{sub 2}{center_dot}0.05Li{sub 2}TiO{sub 3} (x=0.95) which can also be represented in layered notation as Li(Mn{sub 0.46}Ni{sub 0.46}Ti{sub 0.05}Li{sub 0.02})O{sub 2}, can react with one equivalent of lithium during an initial discharge from 3.2 to 1.4 V vs. Li{sup 0}. The electrochemical reaction, which corresponds to a theoretical capacity of 286 mAh/g, is hypothesized to form Li{sub 2}(Mn{sub 0.46}Ni{sub 0.46}Ti{sub 0.05}Li{sub 0.02})O{sub 2} that is isostructural with Li{sub 2}MnO{sub 2} and Li{sub 2}NiO{sub 2}. Similar low-voltage electrochemical behavior is also observed with unsubstituted, standard LiMn{sub 0.5}Ni{sub 0.5}O{sub 2} electrodes (x=1). In situ X-ray absorption spectroscopy (XAS) data of Li(Mn{sub 0.46}Ni{sub 0.46}Ti{sub 0.05}Li{sub 0.02})O{sub 2} electrodes indicate that the low-voltage (<1.8 V) reaction is associated primarily with the reduction of Mn{sup 4+} to Mn{sup 2+}. Symmetric rocking-chair cells with the configuration Li(Mn{sub 0.46}Ni{sub 0.46}Ti{sub 0.05}Li{sub 0.02})O{sub 2}/Li(Mn{sub 0.46}Ni{sub 0.46}Ti{sub 0.05}Li{sub 0.02})O{sub 2} were tested. These electrodes provide a rechargeable capacity in excess of 300 mAh/g when charged and discharged over a 3.3 to -3.3 V range and show an insignificant capacity loss on the initial cycle. These findings have implications for combating the capacity-loss effects at graphite, metal-alloy, or intermetallic negative electrodes against lithium metal-oxide positive electrodes of conventional lithium-ion cells.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); EE
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 949626
- Report Number(s):
- ANL/CMT/JA-42683; TRN: US201012%%410
- Journal Information:
- Electrochem. Commun., Vol. 4, Issue 6 ; Jun. 2002; ISSN 1388-2481
- Country of Publication:
- United States
- Language:
- ENGLISH
Similar Records
LiMn{sub 2{minus}x}Cu{sub x}O{sub 4} spinels (0.1 {le} x {le} 0.5): A new class of 5 V cathode materials for Li batteries. 1: Electrochemical, structural, and spectroscopic studies
LiMn{sub 2-x}Cu{sub x}O{sub 4} spinels (0.1 {le} x {le} 0.5) - a new class of 5 V cathode materials for Li batteries : I. electrochemical, structural and spectroscopic studies.