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.

Journal Article · Sat Jun 01 04:00:00 EDT 2002 · Electrochem. Commun.

DOI:https://doi.org/10.1016/S1388-2481(02)00346-6· OSTI ID:949626

Johnson, C S; Kahaian, A J; Kim, J -S; Kropf, A J; Vaughey, J T; Thackeray, M M

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 Laboratory (ANL)
• Sponsoring Organization: SC; EE
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 949626
• Report Number(s): ANL/CMT/JA-42683
• Journal Information: Electrochem. Commun., Journal Name: Electrochem. Commun. Journal Issue: 6 ; Jun. 2002 Vol. 4; ISSN 1388-2481
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

25 ENERGY STORAGE
ABSORPTION SPECTROSCOPY
CAPACITY
CONFIGURATION
ELECTROCHEMISTRY
ELECTRODES
GRAPHITE
LITHIUM
OXIDES