The
electrode drying process is a crucial step in the manufacturing
of lithium-ion batteries and can significantly affect the performance
of an electrode once stacked in a cell. High drying rates may induce
binder migration, which is largely governed by the temperature. Additionally,
elevated drying rates will result in a heterogeneous distribution
of the soluble and dispersed binder throughout the electrode, potentially
accumulating at the surface. The optimized drying rate during the
electrode manufacturing process will promote balanced homogeneous
binder distribution throughout the electrode film; however, there
is a need to develop more informative in situ metrologies
to better understand the dynamics of the drying process. Here, ultrasound
acoustic-based techniques were developed as an in situ tool to study the electrode drying process using NMC622-based cathodes
and graphite-based anodes. The drying dynamic evolution for cathodes
dried at 40 and 60 °C and anodes dried at 60 °C were investigated,
with the attenuation of the reflective acoustic signals used to indicate
the evolution of the physical properties of the electrode-coating
film. The drying-induced acoustic signal shifts were discussed critically
and correlated to the reported three-stage drying mechanism, offering
a new mode for investigating the dynamic drying process. Ultrasound
acoustic-based measurements have been successfully shown to be a novel in situ metrology to acquire dynamic drying profiles of
lithium-ion battery electrodes. The findings would potentially fulfil
the research gaps between acquiring dynamic data continuously for
a drying mechanism study and the existing research metrology, as most
of the published drying mechanism research studies are based on simulated
drying processes. It shows great potential for further development
and understanding of the drying process to achieve a more controllable
electrode manufacturing process.