Experimental Equipment

Electrode processing can be broken up into five main sections: dry powder mixing, wet mixing, substrate preparation, film application, and drying.

The equipment and preparation stations utilized in this study are presented herein. A visual overview of the ETSL experimental facility can be seen in Figure 2.

The electrode substrate and slurry preparation station is shown in Figure 3. The IKAtube mixer pictured ensures the uniform dispersion of the electrode components (activematerial, conductive additive, and binder) within the slurry.

The binder preparation and dry powder mixing station is shown in Figure 4. The highaccuracy of the Ohaus scale ensures accurate and high precision measurements for thedetermination of critical electrode properties, such as specific capacity. The digitalmicrometer (in case) allows for the determination of film thicknesses in increments of0.001 mm.

The vacuum oven and film applicator are pictured in Figure 5.

Figure 5.Tmaxcnvacuum oven and Elcometer film applicator.

The vacuum oven is capable of reaching temperatures up to 250C with a pressure range of -0.1 Mpa~0 Mpa (atmospheric pressure). The oven allows for quick second-stage drying of electrode sheets, while also removing any bubbles present in the electrodesheet surface. The film applicator (used in conjunction with the pictured doctor blade) ensure a smooth, even electrode casting. 11 preset traverse speeds are available, from 0.5-10cm per second. Lastly, our coin cell crimper(Xiamen Tmaxcn Inc.)is pictured in Figure 6 within ourvacuum glove box(Xiamen Tmaxcn Inc.). The glovebox has a pure argon environment with O2 and H2O levels maintained below 0.5 ppm at all times. The crimper (which seals coin cells) can be used on CR2032, CR2025, and CR2016 coin cells.

Figure 6. Coin cell crimper pictured within glove box.

After finalizing the construction of the coin cells, they are electrochemically characterized via the usage of the ARBIN BT2000 and VMP3 systems shown in Figure 7.

Cathode and Coin Cell Preparation

Moving on to cell construction, first the cathode is centered in the coin cell case.After, several drops of electrolyte are applied to the electrode surface. Enough electrolyte should be applied such that the electrode surface is wetted and a ring of electrolyte can be observed on the outer edge of the coin cell case. Then a single¾”diameter separator is applied to the surface. Care must be taken to center the electrode and prevent bubbles from forming under the PP PE separator . Any bubbles that do become trapped can be forced out using the flat edge of a pair of tweezers. If the electrode moves out of the center, the case can be grabbed by the lip and lightly tapped to force the electrode into position. An additional drop or two of electrolyte can be applied to allow for better movement of the electrode if it sticks to its original position. Next, the gasket is placed into the cell. After applying a few more drops of electrolyte, the lithium counter electrode may be placed, along with the coin cell case. The cell is then filled to the brim with electrolyte and the cap is carefully placed on top. Care must be taken to avoid excessive loss of electrolyte. The cap can then be pressed down using a thumb, and then transported to the crimper using tweezers. After sitting the cell in the grooves of the crimpers, the pressure can be applied up to 900-1000 psi and then released. The cell should appear as shown in Figure 14, with no broken edges. An additional schematic of the placement of the cell components can be seen in Figure 15.