Fabrication of Lithium-ion coin cell

The fabrication of electrodes of lithium-ion battery consists of a series of processes. In the first step, dry mixing of active material, additives, and binders is done. The solvent is added, dispersed, and homogenized to make slurry in the second step.

Anode Electrode

Active material: Graphite

Conductive carbon black: Nano microscopic carbon

Additives: SBR

Binder: CMC

Solvent: deionized water

Cathode Electrode

Active material: Li(NiMnCo)O₂

Conductive additives: namely acetylene black

Binder: PVDF

Solvent: N-methyl-2- pyrrolidinone (NMP)

The mixing and mechanical grinding of the active material have to be carried out separately for a time period of 30 min to 5 hours to ensure good homogeneity. The temperature for the process should be 20-40 degrees Celsius. The current collector foil is coated with the slurry using an application tool (e.g., slot die, doctor blade, anilox roller). The coating can be done either continuously or intermittently. Coating thickness accuracy, homogeneity in and across the coating direction, surface quality, and adhesion between coating and substrate should be considered in step. The resulting slurry is then coated onto the current collectors, and the coated substrates are then subjected to vacuum drying. The temperature profile in dryer zones should be between 50- 160 degrees Celsius. The process is followed by roll pressing to ensure a firm coating. The substrates are cut into desired dimensions in an electrode cutting machine in the ensuing step. The resulting electrode materials are then assembled in an Ar-filled glove box with O₂ and H₂O concentrations less than 0.1 ppm. 

fig: Process flow diagram of coin cell fabrication

During the stacking process, the separated electrode sheets are stacked in a repeating cycle of the anode, separator, cathode, separator, etc. A wide variety of stacking technologies exist, which are usually patented by specific manufacturers. Positioning accuracy of the anode and cathode sheet, damage-free electrode surface, and edge are the quality features to be considered. After the stacking of electrodes, electrolytes are injected into the separator, and then the fabricated cell is sealed within the metal casing by means of a crimping machine. Dosing and distribution accuracy of the electrolyte in the cell, no electrolyte residues in the sealing seam and tightness of the sealed cell should be ensured.

YOU  MAY LIKE THESE POST

Fuel Cell Technology

Fundamentals of Doping and Electronic Band Structure in Doped semiconductor