Electric vehicle battery current collector assembly
By this time, you may already have ample knowledge about electric vehicle batteries, in particular, lithium-ion batteries which are the most popular and most commonly seen in EVs today.
There is a term, however, that you may have come across in your readings about electric vehicle batteries. This term is “current collector”. What is a current collector? Are they components of EV batteries?
We’ll discuss the EV battery current collector assembly in this article, addressing what it is and why it is important in EV batteries.
What are current collectors in a battery?
A current collector is one of six components – the other components are the two electrodes anode and cathode, electrolyte, separator, and casing – of electric vehicle battery. At the individual battery cell level, current collectors come in the form of thin, light metal foils which serve as support for the coating of the two electrodes.
While the above description of the battery current collector is for individual battery cells, when it comes to battery modules, we now have the current collector assembly or CCA, which come in the form of layers or plates.
What is the purpose of current collectors?
Current collector plates serve the purpose of functioning as an interface for an entire group of individual EV battery cells to combine their power into a single output to external circuits, which meets the desired performance specified for a particular EV battery’s design.
Take for example the Interplex Cell-PLX™ interconnect system. This customizable solution features a current collector plate with positive and negative terminals formed from laser weld or wire bonding. On each side of the plate is a laminated busbar.
In the assembly of EV battery modules, the individual battery cells are held in place by a grid-like battery cell holder, with the current collector plate and busbar placed on top.
Current collectors may come as a single layer or multiple layers depending on the battery design specifications. In most cases, the battery cells are connected to either a thicker current collector or two or more current collectors separated by a dielectric layer.
Components of current collectors
In an individual EV battery cell, the current collector for the anode is commonly made of copper. On the other hand, the current collector for the cathode is made from aluminum.
However, in any specific current collector assembly, the components may vary based on the electric vehicle battery design. Typically, the six main components of a CCA are copper, aluminum, nickel, titanium, stainless steel, and carbonaceous materials. The materials of these EV battery cells and components influence the capabilities and other aspects of the EV battery.
Why is it important to understand CCA in EV batteries?
Understanding the importance of a current collector assembly (CCA) is critical for the design and proper functioning of an EV battery, more specifically lithium-ion EV batteries.
These key aspects include the following:
- Battery capacity – the amount of aggregate energy from battery cells that can be handled by the collectors
- Rate capability – the rate of discharge of the EV battery
- Electrochemical stability – the stability of energy exchange between the two electrodes in the individual EV battery cells and in the battery as a whole
- Electrical conductivity – the rate by which electrical energy flows from the battery through the various systems of an electric vehicle
- Mechanical property – stability of the EV battery against environmental stresses
- Density – the amount of energy as compared to the battery size. Current collectors in today’s EV battery design are thinner to increase energy density
- Sustainability – how components of CCAs can readily be recycled
Another important aspect to consider is that current collectors have been found to undergo dissolution and corrosion in the course of electrochemical cycling. This can lead to a number of detrimental effects, including the limiting of battery power, a reduction in the normal operation of the battery due to reduced lithium-ion mobility and electrical conductivity, and the loss of battery cell capacity.
Of even greater importance is that battery safety can be impacted by current collector degradation, which may lead to short circuits, sudden increase in temperature, and potential catastrophic failure.
It is important to understand how materials selection and design practices for current collector plates can help to mitigate the amount of degradation and keep EV batteries functioning at high performance levels over extended life cycles.
You can learn more about the customizable current collector assembly by contacting Interplex here.
