Table of Contents

Quick Quote

What’s the 4680 battery?

On Tesla Battery Day 2020, Tesla launched its game-changing 4680 Lithium-ion battery, thus taking pole position in the race to build large batteries. In the photo below, you can see the key features of the Tesla 4680 projected on the screen behind Elon Musk, during the event. The name 4680 indicates its cylindrical  Form Factor, having a diameter of 46mm and a length of 80 mm.

What’s the 4680 battery

The Tesla 4680 delivers 5 times the energy and 6 times the power of its immediate predecessor in the Tesla portfolio, the 2170 battery. With 4680, Tesla expects an increase of 16% in the vehicle range. And to top it all, the 4680 is designed as a structural battery pack component. This means that the battery pack will absorb some of the structural loads of the car, thereby achieving overall light-weighting.

So how did Tesla manage to accomplish such a huge performance boost? Is this the future of Tesla electric vehicles? What is it going to cost? Who are the other players in the large battery space? To answer these questions and more, let us delve deeper into the technicalities of the 4680 battery.

Key Features of Tesla’s 4680 Battery

Big Size More Power

The first and obvious thing one notices about the battery is its large size. The volume of 4680 is five and a half times that of 2170.  This allows a bigger Jelly Roll to be accommodated. In battery parlance, a Jelly Roll is a multilayered cylindrical sandwich roll formed by electrolyte gel placed between sheets of Cathode, Separator, and Anode. A larger Jelly Roll increases the quantity of active charge carriers and electrode surface areas. This translates into greater power storage and delivery from each cell. Figure 2 illustrates the Jelly Roll concept.

Big Size More Power

Tablets Battery

The Tesla 4680 uses a patented Tabless Design, which dramatically reduces internal electrical resistance. Tabs are conductive metallic pieces or strips welded to the Anode and Cathode electrode sheets.  Figure 3 illustrates a battery with two Tabs.

Tablets Battery

Tabs are the junctions where electrons flow between the external circuit and the battery electrodes. During charging, Lithium atoms embedded throughout the rolled-up Cathode sheet release electrons. Similarly, during cell discharge, Lithium atoms embedded throughout the Anode sheet in the Jelly Roll release electrons. In both cases, these electrons must travel to the respective Tabs, to enter the external circuit.

The challenge with large batteries is that a longer path for electrons generates more heat and voltage drop due to ohmic resistance. Battery designers have tried out multiple closely spaced tabs to mitigate this problem. However, these are difficult to fabricate and increase the risks of damage to electrodes during welding. Tesla found an ingenious solution for this, by doing away with the Tabs altogether! Instead, the 4680 battery has conductive strips that run all along the edges of the Anode and Cathode sheets, as represented in Figure 4.

This way one entire edge of the Anode and Cathode sheets can perform the same function as Tabs, dramatically reducing electrical resistance and heat generation.

electrical resistance and heat generation. 

New Chemistry

Tesla has announced that the 4680 battery will have new chemistry to significantly enhance performance and reduce costs. In the future, the Cathode will not use the proven recipe of Lithium Oxide with 80% Nickel 10% Cobalt, and 10% Manganese (called NMC-811). Instead, their 4680 batteries will have Cathodes with much higher Nickel content and lower Cobalt content. The targeted Cathode composition is NMC 955 which is 90% Nickel and 5% each of Manganese and Cobalt. Higher Nickel content improves energy density, though it introduces problems of electrode stability, which Tesla may have overcome. Reducing Cobalt content is necessary to reduce dependence on the Congo region, which supplies 70% of the world’s Cobalt. It will also lower Cathode costs.

Tesla’s improvements in Anode chemistry involve replacing Graphite substantially or completely with raw metallurgical Silicon. Since Silicon of the required grade is abundant in the Earth’s crust and relatively cheap, switching to Silicon will reduce the cost of Anodes. The problem with Silicon Anodes is their volume expansion when Lithium atoms enter the Anode during charge and discharge cycles. This eventually destroys the electrode. However, given their announcements, Tesla seems to have found a solution.

Overall, Tesla expects reduced battery costs and increased range due to these chemical innovations.

Thicker steel case

Tesla has used a  much thicker steel case for 4680 compared to its 2170 counterpart. This may be because these batteries will be installed in a structural battery pack and must endure higher mechanical loads. One can also view this as additional protection against impact damage.

Pros and Cons

While some of Tesla’s announcements may be marketing hype, the fact remains that by January 2022 they had already produced a million cells of the 4680 battery. In an earnings call last year after the first quarter results of 2023, they confirmed progress on building the Texas Giga factory that will manufacture second-generation 4680 cells. This makes them the clear leader of the field in the 4680 battery business.

Many top battery manufacturers are developing 4680 format battery designs, and some are going ahead with production scale investments. Thus, the 4680 battery is going to shake up the electric vehicle world shortly. What does this mean to the “average Joe” consumer? Based on what we know at this time, let us look at the pros and cons.

Pros

  • Tesla’s 4680 promises to deliver increased mileage and reduced costs per kWh due to increased energy density, better battery chemistry, and overall vehicle light-weighting due to its structural battery design.
  • The Tesla 4680 is expected to last at least a million miles, which is much more than the average user will drive in the car’s lifetime.
  • The battery design incorporates enhanced safety features such as better heat dissipation and reduced risk of manufacturing defects due to the Tabless design.
  • Tesla has already produced several million first-generation 4680 cells and gained valuable manufacturing and operating experience with this new battery. Their gigafactory in Texas will deliver improved versions of the 4680. The battery design is maturing, which reduces the risk of ownership or investment.

Cons

  • At present, the 4680 is intended only for the new Tesla Model Y priced at around $ 60,000. This may not be affordable for many.
  • The claims made regarding new battery chemistry have not been implemented in the first generation of 4680 batteries, which seem to be NMC 811 and Graphite. It may take time for Tesla’s high Nickel, high silicon 4680 cells to be launched in the market.
  • Competitors may come up with better 4680 battery designs as well as other options including Sodium ion or solid-state batteries.

Evolution of the Cylindrical Battery Cell

In Akira Yoshiro’s Nobel Lecture delivered in 2019, he traces the evolution of Lithium-ion battery technology. The 1990s saw the introduction of mobile phones, which became an excellent fit for the newly invented lightweight and energy-dense Lithium-ion batteries. Initial markets were entirely in the personal electronics segment, till in the year 2010, when they were introduced into the electric vehicle market. Figure 5, cited in his lecture, illustrates the growth of the Lithium-ion battery market since 2010.  You can see how dramatically electric vehicles are projected to dominate the market share by 2025.

Evolution of the Cylindrical Battery Cell

The first electric car to be launched commercially using Lithium-ion batteries was the Nissan Leaf. The first-generation model was in production from 2010 to 2017. It used flat laminated Lithium-ion cells. In battery terminology, this is the “Pouch format”. The latest Nissan Leaf continues to use Pouch-type batteries.

The three battery shapes currently used by electric car manufacturers are Pouch, Prismatic, and Cylindrical types In the year 2020, the market share of each battery type in the passenger vehicle category was Prismatic ~40%, Pouch ~35% and Cylindrical ~15%.

Tesla was the first to use the cylindrical Lithium-ion cell for their electric vehicles. They started with the relatively cheap, but proven Panasonic 18650 and then moved to the 2170 form factor. Now they are transitioning to the much larger 4680 cell. Other manufacturers like BMW and CATL were later adopters of cylindrical batteries. However, the market driver is Tesla and the evolution of cylindrical Lithium-ion batteries mirrors the evolution of Tesla. Figure 6 shows examples of the cylindrical batteries that are powering Tesla’s growth.

4680 Battery vs 18650 Battery

To consumers, what ultimately matters is the economics and convenience of ownership. Tesla is the world’s largest electric vehicle maker in the world, and their path to success has involved the use of cylindrical Lithium-ion batteries. So let us compare the three cylindrical cells powering Tesla cars, from a consumer’s perspective.

4680 Battery vs 18650 Battery

How does the youngest and largest Tesla battery compare with its oldest and smallest counterparts? To answer this, let us compare the 4680 and 18650 batteries :

Parameter 4680 18650 Remarks
Capacity (maximum) 25000 mAh 3500 mAh Due to higher mAH, the 4680 will last longer between recharges
Energy density (cell) 276 to 333 wh/kg 250 wh/kg 4680 can deliver more power.
Size 46 mm dia. x 80 mm ht. 18 mm dia. x 65 mm ht. Due to larger size, 4680 contains a bigger Jelly Roll and can store more energy
Steel case wall thickness 0.5-0.6 mm 0.22 to 0.28 mm 4680 has higher mechanical strength to withstand shock
Cycle life 1000-2000 1500-4000 4680 has lesser cycle life than 18650 but will require less frequent charging
Net weight (maximum) 355 gms 50 gms The 4680 is heavier and suited for bigger cars.

4680 Battery vs 2170 Battery

Since the 2170 battery is the immediate predecessor to the 4680 in Tesla’s evolutionary history, the comparison below should be of interest:

Parameter 4680 2170 Remarks
Capacity (maximum) 25000 mAh 5600 mAh Due to higher mAH, the 4680 will last longer between recharges
Energy density (cell) 276 to 333 wh/kg 276 to 300 wh/kg The difference is not much.
Size 46 mm dia. x 80 mm ht. 21 mm dia. x 70 mm ht. Due to its larger size, 4680 contains a bigger Jelly Roll and can store more energy
Steel case wall thickness 0.5-0.6 mm 0.22 to 0.34 mm 4680 has higher mechanical strength to withstand shock
Cycle life 1000-2000 1500 Similar cycle life
Net weight (maximum) 355 gms 70 gms The 4680 is heavier and suited for bigger cars.

Conclusion

The new 4680 battery launched by Tesla is indeed a game changer due to its enhanced power and range. The safety features are now better. The key factor is going to be the battery cost, which hinges upon successfully incorporating lower costs of Cathode and Anodes

Facebook
Twitter
LinkedIn
WhatsApp
Scroll to Top