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The Tesla Tabless Electrode Battery Breakthrough

Tesla has patented a design for developing a tabless electrode battery.


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Vincent T

3 years ago | 4 min read

Tesla has patented a design for developing a tabless electrode battery. According to company head Elon Musk, people don’t realize it but it is “Way More Important Than It Sounds”.

So what makes the new battery design important?

Conventional Battery Design Constraints

The Tesla patent was described as a “Cell With A Tabless Electrode”. Traditional batteries with tabs use a jelly-roll design in which the cathode, anode, and separators are rolled together.

The cathode are the positive end of a terminal where electrons flow out of a device while the anode is the negative end of a terminal where electrons enter a device.

The anode is the source of the electrons to an external circuit while the cathode is the sink. Separators are seals that prevent the cathode and anode from coming into contact.

If contact were made no electrons flow as there is no potential difference, but it can lead to damage from a short circuit if there is direct contact between the two electrodes when the circuit is closed.

Between the two electrodes is the electrolyte, which is a chemical substance (e.g. soluble salt) that helps move Lithium ions during a discharge (when battery is in use) and the reverse process during recharging the battery.

This results in free electrons that conduct a path through a circuit to power a device during discharge and charge back the battery during the recharging phase.

Sample illustration of new tabless electrode battery (Source Tesla Patent)

The design of the Tesla battery prior to the patent used a cylindrical cell with tabs for the electrode. The cells are then assembled into a battery module and placed at the bottom of the car (e.g. Model S, Model X, Model 3).

Normally tabs provide the current to the circuit that powers a device, in this case the EV (Electric Vehicle). The tabs have to be connected to the circuits they are powering using specialized welding during the manufacturing process.

This according to Tesla “… increase costs and present manufacturing challenges”.

Tabs also create more resistance which can generate more heat, so that leads to less efficiency for energy transfer. This was the reason to come up with a better design for batteries.

Typical assembly of a cylindrical Li-Ion Battery showing the tabs (Source: Electrochemical Society)

Tabless Electrodes Are Tesla’s Answer

A tabless electrode would make battery production faster. It will also increase efficiency and reliability for the battery. By removing the tabs, the connection can make use of taps or spikes that connect directly to components that don’t require welding.

The design increases the conductivity via the connection with less ohmic resistance to transfer energy more efficiently. This can be useful for supercharging and fast charging Tesla vehicles.

According to the patent:

“The maximum distance current will travel is therefore the height of the electrode as opposed to its length. Depending on the cell form factor, the height of an electrode is typically 5% to 20% of its length. Therefore, the ohmic resistance in the negative electrode during electrochemical cycling can be reduced by 5 to 20 times via embodiments of the present disclosure.”

This could likely lead Tesla to cease development of portable battery packs and instead return to an integrated battery module.

That would mean moving to a less flexible and non-removable type, which is similar to how Apple makes their computers. Since the manufacturing of tabless electrodes will do away with complicated welding, the battery modules can be smaller so they take up less space.

Synopsis

Tesla has been planning to manufacture all components of its batteries, and this was part of that plan. This is in order to reduce their overhead and sourcing from battery manufacturers, who can sometimes fall short when it comes to requirements.

This was probably learned from lessons in the past with Tesla’s relationship with Panasonic regarding the cost of battery cells. Overall, this new outlook in battery design and production aims to make Tesla more self sufficient.

The new design can lead to faster charging rates, hypothetically speaking (no official data available as of June 2020). It can bring down charging time for all levels of the Tesla EV.

This is based on the assumption that lower internal resistance in the battery will lead to faster charging. Less internal resistance means less heat generation and more efficiency when charging.

Longer range is also a benefit target.

This is a part of the Tesla’s effort to build a Million Mile Battery, which could help reach the 4,000+ cycles for total 1 million mile battery range (total miles the battery can provide). However it is more due to the redesign in the cells rather than the actual tabless electrode.

The tabless electrode could just be a part of the plan, but not the actual cause of increasing the range. Another Tesla patent describes a cathode design using a next-generation “single crystal” NMC (Nickel Manganese Cobalt Oxide).

A long range Tesla Model S battery can provide an estimated 391 miles (Source Tesla)

Even if the tabless electrodes are not the main cause for extending range, it is part of the overall design to make batteries more efficient and longer lasting.

The tabless redesign of the battery was mainly to address issues with constraints. This would lessen production time and costs in the manufacturing process.

According to other reports, Tesla could reach $100/kWh for battery packs. That is the level at which electric vehicles reach the same level as internal combustion engines in terms of cost.

Competitors like GM are already planning on driving costs lower than $100/kWh, so Tesla is not ahead on this. Perhaps more information can be clarified on Tesla’s “Battery Day” (No definite date announced as of writing).

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Vincent T

Involved in blockchain development and imaging technology.


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