An electrode is the electrical part of a cell and consists of a backing metallic sheet (current collector) with active material printed on the surface. In a battery cell we have two electrodes:
- Anode – the negative or reducing electrode that releases electrons to the external circuit and oxidizes during and electrochemical reaction.
- Cathode – the positive electrode, at which electrochemical reduction takes place. As current flows, electrons from the circuit and cations from the electrolytic solution in the device move towards the cathode.
Anode-Cathode – in chemistry, we define Cathode as the electrode where reduction takes place and Anode the electrode where oxidation occurs. Both, during the discharge and recharge electrons move from the Anode to the Cathode. {Anode and Cathode swap places}.
It is useful to look at the cell stack. Actually a slice through the cell stack.
In the cell stack we can see the Cathode Electrode facing onto the Anode Electrode with the separator between.
The separator isolates the two electrodes electrically whilst still allowing ions to pass through.
Dry Electrode
Eliminating the solvents in the processing and coating of the electrodes has a number of benefits:
- environmental friendliness
- lower cost
- reduced production footprint and capex
- enhanced battery performance
However, this is a significant technical step and has some disadvantages. Some of these issues are due to the lower maturity and breadth of development.
Electrode Dimensions
A key aspect of any cell format or detailed design is the estimation of the electrode lengths.
3D Electrodes
Another way to increase energy density is with 3D electrodes. Increasing the surface area and connection to the active materials can improve a number of features of the cell.
See also: Electrolyte, Cell Design, Engineering Empty Space: Tailoring Battery Electrodes for Ion Transport, Why Electrode Microstructure Architecture Determines Cell Performance