Coin Cell Battery Chamber Design for Low-temperature Operando Experiments

As the world becomes increasingly electrified, batteries play a key role in energizing our devices. From powering our electric vehicles to providing energy storage for grid-level renewable energy sources, it is becoming increasingly important to develop batteries that exhibit high performance in a wide range of climates. Battery performance is often reduced in cold weather environments, which necessitates more research focused on low temperature battery investigations.

However, commercially available low temperature battery cycling equipment tends to be expensive, preventing these studies from being performed in research facilities that do not focus on non-ambient experiments. We report here a simple cost-effective temperature chamber design that is easy to assemble and fast to implement, allowing more low temperature battery research to be conducted. This design enables reliable temperature to four 2032 coin cells in low humidity environments to reduce corrosion and condensation issues.

In this protocol, we will be going through the main steps of manufacturing the chamber before demonstrating how to use the chamber. Additional instructions are provided in the full text. First, 3D print all of the supplemental STL files except the chamber and chamber lid files using PLA.

Second, mill the acetol resin block to the provided dimensions. We use a CNC or manual milling machine to create the main chamber and lid as showing the chamber and chamber lid supplemental files. Also cut the heat sinks to size and drill through-holes according to the hole layout file.

You should now have all of the parts that require a machine shop. Slide the four battery holders through the battery wiring slider and then through the lid. Make sure that each of the battery holder tabs are in the on"position.

Connect all of the wiring in figure 2 except the thermoelectric modules and 12 volt fans. These will be connected later. Solder the 12 volt and ground lines to the power supply to 2-wire connector.

Create the gaskets by first cutting the gasket material using a cutting tool and the gasket jig to make two gaskets. Apply light pressure to avoid pulling the gasket from under the jig and cutting too much. Place the gasket in one of the main chamber's side pockets so that it is flat in the pocket.

Put the thermoelectric module wires through the side holes in the main chamber with the numbered cold side of the thermoelectric modules facing into the chamber. Apply a thin but complete layer of thermal grease to the thermoelectric non-numbered hot side. Apply a thin ring of silicone to the chamber outside the thermoelectric module.

Carefully place a heat sink on top of the main chamber. Screw the heat sinks into the main chamber to squeeze the silicone. This will form an airtight seal.

Remove any excess silicone. Repeat on both sides. After sliding the lid and thermocouples into the chamber, place the two 12 volt fans on either side of the heat sinks.

Orient it to blow into the heat sinks. Use three long zip ties to tighten the fans into place. Adhere the switch mount and protoboard mount to the heat sink clamp prints with instant glue.

Slide the mounts onto the top row of the heat sinks. Place the protoboard, on-off switch, controller, and insulated material in their respective positions on the mounts. After organizing the wires, solder the connections for the thermoelectric modules and the 12 volt fans.

The chamber is now fully assembled. To cool the chamber to the appropriate temperature, turn thermoelectric modules off with the manual on-off switch. Set the controller to be in cooling mode.

Set the desired temperature to 0 degrees Celsius and the turn off differential to 0.1 degrees Celsius. Set the range of temperatures to negative 55 to 24 degrees Celsius to prevent extreme overheating or over-cooling in outlier circumstances. After connecting the data logging thermocouple to the thermometer and placing the chamber in the fridge, turn the on-off switch back on.

The chamber is now ready for use. To open the chamber to add or remove batteries, place a screwdriver on the underside of the lid's bolt. Using the outer edge as a fulcrum, push down on the screwdriver's handle.

Once the lid is loose, pull it out with your hand and set it down on a flat surface or in the provided 3D printed lid holder and replace it with a temporary lid. Open the battery holders that you wish to replace and place the coin cell inside the holder. Remove the temporary lid and then the silica gel packet inside the chamber.

Wipe away any moisture with a cloth and replace the silica gel packet in the chamber to help absorb any additional moisture. Replace the main lid. It may take up to two hours for the temperature to re-equilibrate inside the chamber.

In order to assess the reliability of the chamber to maintain a constant temperature of 0 degrees Celsius, its performance was tested in three ways. First, we used an automated temperature data logger to measure the temperature gradients across the chamber. The temperature variation throughout the chamber was consistent and only varied 4 degrees Celsius.

Second, the temperature stability of the newly assembled chamber was monitored over a period of a single day, which maintained a temperature variation of 13 degrees Celsius. To test the long-term performance, after using the device for seven months, a week long measurement was performed, which showed a slightly reduced temperature variation of 75 degrees Celsius. Lastly, four lithium-ion 2032 coin cells were cycled 100 times for three months.

The cycling data shows consistent performance and low noise over the course of this experiment. These results demonstrate that the chamber can maintain constant temperature and it allows for the low temperature electrochemical cycling experiments to be performed reliably. We presented here a simple design to enable cost effective low temperature battery cycling for 2032 coin cells in a low humidity environment.

The performance test show that this device exhibits reliable long-term performance with temperature variations of less than a single degree Celsius.