Study of LiCoO₂+C₆₀ hybrid cathode using neutron and ion-beam profiling methods

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Physics

Background:

• All-solid-state Li-ion batteries (ASSLIBs) require advanced cathode materials for improved safety and energy density.
• Hybrid cathode structures offer potential for enhanced electrochemical performance.
• Understanding element distribution is crucial for optimizing ASSLIB performance.

Purpose of the Study:

• To prepare and characterize thin films of a hybrid LiCoO2 (LCO) + C60 cathode for ASSLIBs.
• To investigate the depth distribution of constituent elements (Li, Co, C, O) within the hybrid film.
• To determine the influence of the C60 phase and current collector on element distribution.

Main Methods:

• Simultaneous ion beam sputtering of LCO and thermal evaporation of C60 to create hybrid thin films.
• Neutron Depth Profiling (NDP) for precise elemental depth profiling.
• Rutherford Backscattering (RBS) for complementary elemental analysis.

Main Results:

• NDP and RBS confirmed element depth distributions in the sub-micrometer LCO+C60 films.
• The presence of C60 increased Li accumulation on the surface and decreased it slightly below.
• Uneven distributions of Co, C, and O were observed, influenced by C60 and the current collector.

Conclusions:

• The C60 phase significantly impacts Li distribution in hybrid LCO+C60 cathodes.
• Element redistribution occurs at the surface after current collector deposition.
• Electrochemical potential differences are likely responsible for the observed uneven element distributions.