Washington: Japanese researchers have fabricated a cathode (positive electrode) of lithium cobalt oxide (LiCoO2) in which the compound`s individual grains are aligned in a specific orientation, which they claim yields a significantly higher-performing battery than one with a randomly-oriented LiCoO2 cathode.
Primary, or non-rechargeable, batteries and secondary batteries both produce current through an electrochemical reaction involving a cathode, an anode, and an electrolyte (an ion-conducting material).
However, apply an outside current to a secondary battery and the negative-to-positive electron flow that occurs during discharge is reversed. This allows the battery to restore lost charge.
Co-author Tohru Suzuki, said that in a lithium-ion battery, lithium ions move from the anode to the cathode during discharge and back when charging.
Suzuki said that the material in the cathode has a layered structure to facilitate intercalation [insertion] of the lithium ions; if the structure is oriented in a specific fashion, the lithium ions have better access to the lattice and, in turn, charge-discharge performance is improved.
Using a rotating magnetic field, the researchers were able to fabricate the ideal textured microstructure of the individual LiCoO2 grains making up the cathode: a perpendicular alignment of the c-plane (the vertical side) and a random orientation of the c-axis.
Unlike cathodes where the microstructures in both the c-plane and c-axis are randomly oriented, the specialized grains allow easy access for lithium ions while relaxing the stress associated with intercalation.
The study has been published in the journal APL Materials.