Influence of Convective Drying Parameters on Electrode Performance and Physical Electrode Properties

Abstract

In the present work two of the various drying process parameters, air temperature and nozzle speed, are studied and their influence on the electrode’s physical properties is examined by different mechanical and electrical analyzes. It was found that elasticity, electrical volume resistivity and adhesion strength of the coating to the substrate, can be dependent on process parameters used for manufacturing. These properties are also influenced by the electrode’s mass loading and its recipe, as the total solvent content and therefore the drying time plays an important role. Assuming binder demixing during drying allows explaining the results, since evaporating solvent induces a temperature dependent compensational flow of solvent and solved binder. If immobilization occurs faster than compensational flow can cause significant demixing, no binder gradient emerges. The driving force counteracts the drying time, but increases demixing, so that optimum drying conditions exist for each mass loading and solid content.

Measuring the coating adhesion strength of electrodes for lithium-ion batteries

“…Thus a higher volume fraction of the binder is available at the current collector-coating interface to build-up a binder-polymer-matrix with a higher degree of crosslinks towards the current collector. Furthermore the enhanced interaction of the binder molecules and the particulate components of the electrode should be mentioned [26][27][28]. Hence the mechanical interlocking of the coating towards the current collector, which is provoked by the polymer binder chains, is improved.…”

The interaction of consecutive process steps in the manufacturing of lithium-ion battery electrodes with regard to structural and electrochemical properties

“…Additive addition, slurry manufacturing and calendering are only three exemplary process steps, which significantly influence the electrode structure. In addition, the coating and drying of the electrodes is as well known to play a significant role concerning component demixing [37]. Knowing how process parameters affect the structure, precise process-structure functions f a , f b and f g (see Fig.…”

Improvement of Lithium‐Ion Battery Performance by Two‐Layered Slot–Die Coating Operation

“…The conventional method for drying the electrodes in LIBs is to use forced convection air drying. The drying temperature and air flow rate are the main parameters that control the dried electrode quality . Because the energy density requirement for LIBs used in EVs is much higher than that of 3C batteries, a thicker electrode containing more active material has to be used .…”

“…However, high‐temperature drying may also cause surface defects, uneven distribution of particles, binder migrations, and other heterogeneous structure problems. All of these factors may affect the electrochemical performance of the composite LIBs …”

“…Thed rying temperature and air flow rate are the main parameterst hat control the dried electrode quality. [4,5] Because the energy density requirementf or LIBs used in EVs is much higher than that of 3C batteries,athicker electrode containing more active material has to be used. [1] To produce such an electrode,i ti sn ecessary to have at hicker wet film containing al arge quantity of solvent, which has to be removed during the drying process.T his will create not only some operational difficulties,b ut will also affect the drying efficiency and overall production cost of LIBs.O ne simplew ay to accelerate the solvent evaporation rate is to raise the drying temperature.F or example,t he rate for dryingawet film containing N-methyl-2-pyrrolidone (NMP) solvent can increase up to 7times from the normal drying temperature of 60 to 140 8C.…”