Impact of the Calendering Process on the Interfacial Structure and the Related Electrochemical Performance of Secondary Lithium-Ion Batteries

Graphite electrodes, containing 8 wt% binder and 4 wt% conductive additives, manufactured from one batch of a continuous coating and drying process in technical scale, are investigated under variation of specific compression rates. The influence of the calendering process is studied in terms of surface morphology, mechanical, structural and electrochemical properties. Graphite electrodes are found to be sensitive to compaction and a compression rate of 10 % was identified to be beneficial to long term cycling stability, while the impact on power performance was found not to be affected to a high extent. The change of pore structure for specific pore size ranges and the deformation of active material are identified to be crucial factors negatively influencing electrochemical performance. Plastic and elastic deformation energies of the electrode coating layer are derived by nanoindentation. This method is suitable to quantify the electrodes’ mechanics and undergoing particle deformation caused by calendering.