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Electric vehicle battery current collectors assembly (CCA & CCS)

Electric vehicle battery current collectors assembly

By this time, you may already have ample knowledge about electric vehicle batteries, in particular, lithium-ion batteries which are prevalent in EVs today.

But there’s another term you may have encountered: “current collector”. What is a current collector?

In this section we will tackle EV battery current collectors assembly from definition to function.

What are current collectors in a battery?

A current collector is one of six components of EV battery packs: the others being the anode and cathode, electrolyte, separator, and casing. 

As part of how EV batteries are manufactured, current collectors come in the form of thin, light metal foils which serve as support for the coating of the two electrodes.This description of the battery current collector applies to individual battery cells. 

But when it comes to battery modules, we now have the EV current collectors assembly (CCA), which come in the form of layers or plates.

What is the purpose of current collectors?

Current collector plates serve 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 ENNOVI-CellConnect cell contacting 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 cell systems, 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 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 EV battery current collectors assembly, the components may vary based on the EV battery design. Typically, the six main components of a CCA are copper, aluminum, nickel, titanium, stainless steel, and carbonaceous materials. The materials and components of the battery cells influence the capabilities and other aspects of the EV battery.

Why is it important to understand CCA in EV batteries?

Understanding the importance of EV battery 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 at which electrical energy flows from the battery through the various systems of an electric vehicle
  • Mechanical property: refers to 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: refers to 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’s important to note that 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 EV battery current collectors assembly by contacting Ennovi here.

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