Since the original Roadster in 2008, Tesla has been at the forefront of electric vehicle technology. A key driver behind their success has been rapid advancement in battery design and chemistry. Each new Tesla model has introduced battery innovations unlocking more range, better safety, and lower costs.
In this comprehensive guide, we will explore Tesla‘s battery cell journey and compare the key attributes of their different cell types over time.
18650 Cells – Tesla‘s Foundation
The original Tesla Roadster launched in 2008 relied on tried and tested 18650 lithium-ion cells. These were sourced from Panasonic, who were already mass producing the cells for laptops and other consumer devices.
18650 Cell Manufacturing
The 18650 cell production process has been refined over decades of high volume manufacturing, especially driven by laptop and tablet demand.
Key steps in the 18650 production flow involve:
- Coating metal foil sheets (typically aluminum & copper) with cathode & anode slurry mixtures
- Stacking and aligning foil sheets in a jelly roll structure
- Sealing rolled sheets in a cylindrical steel canister
- Injecting electrolyte liquids and sealing the cell
- Testing & grading based on capacity
Automation is critical throughout to ensure precision and quality at scale. Top tier OEMs like Panasonic and LG Chem have perfected this process enabling low cost outputs.
18650 Dimensions
As the name indicates, 18650 cells have a 18mm diameter and 65mm height form factor. This cylinder shape complemented laptop rectangular battery compartment designs. It also created modular building blocks that could be bundled in different series & parallel configurations for various devices.
18650 Chemistry
The cathode chemistry used in the original Tesla Roadster cells was nickel cobalt aluminum (NCA). This delivered high energy density to maximize driving range, which was an important consideration for convincing early adopters about EV viability. Gradual simplifications of manufacturing have also now made NCA a cost effective option.
Tesla also used these cells in the Model S and Model X with gradually increasing capacity over their lifecycle. By 2019, the top Model S 100D+ utilized 3360 18650 cells to provide a class-leading 370 miles EPA range.
18650 Cell Key Attributes:
- Dimensions – 18mm x 65mm
- Cathode Chemistry – Nickel Cobalt Aluminum (NCA)
- Energy Density – High (~250 Wh/kg)
- Cycle Life – 1000+ cycles
- Models Used – Roadster, Model S, Model X
2170 Cells – Lower Cost and Higher Volumes
As Tesla transitioned from low volume premium EVs to higher volume affordable models like the Model 3, battery costs and availability became critically important. This drove innovations in cell design and chemistry within the 2170 form factor.
2170 Manufacturing Streamlining
To make the Model 3 viable, Tesla had to achieve order of magnitude reductions in battery costs while securing reliable supplies. This lead to a joint venture Gigafactory with Panasonic to co-optimize the production process.
By localizing and linking cell production directly adjacent to EV manufacturing, costs could be trimmed through scale and simplification. The custom 2170 cell format redesigned with Tesla‘s needs in mind was instrumental make this possible.
Output quality was also enhanced through close collaboration between Panasonic and Tesla. Today, Panasonic runs 5 fully automated lines producing 2170 cells at the Nevada Gigafactory.
2170 Dimensions
The new 2170 cell format increased dimensions substantially – 21mm diameter and 70mm height. Compared to 18650, this boosted per cell capacity by over 50%. The larger surface area and simplified cylindrical shape also improved heat dynamics.
2170 Chemistry
Most importantly, Tesla switched cathode chemistry from NCA to nickel cobalt manganese (NCM). This reduced expensive cobalt demand by over 60% while increasing nickel which is cheaper and offers better energy density.
The improved performance, lower cost, and supply chain scale of 2170 cells was essential to make Model 3 production viable. Today, Tesla sources these cells from both Panasonic and LG Chem to fulfill demand across their lineup.
2170 Cell Key Attributes:
- Dimensions – 21mm x 70mm
- Cathode Chemistry – Nickel Cobalt Manganese (NCM)
- Energy Density – High (~260 Wh/kg)
- Cycle Life – 1000+ cycles
- Models Used – Model 3, Model Y
4680 Cells – Next Generation Performance
While 2170 cells enabled Tesla‘s volume journey, further innovations were required to realize Elon Musk‘s vision of a mass market $25,000 EV. The 4680 cell announced in 2020 tackles this challenge with a completely reimagined architecture.
4680 Simplified Design
The 4680 removes tabs connecting cells, enabling a structural battery enclosure to link modules directly. This allows simplifying cell production while improving thermal propagation resistance.
Eliminating tabs also unlocks faster charge rates. 4680 cells have already demonstrated capability to charge at over 7C rates for short durations. Combined with better heat dissipation, this enables new charging architectures.
4680 Manufacturing Strategy
Initially, Tesla partnered with Panasonic to manufacture prototype 4680 cells at the Nevada Gigafactory using existing 2170 lines. This allowed rapid design iteration leveraging their tight integration.
However, with the 4680 Tesla is now also investing in its own dedicated production lines separate from Panasonic. The new $3.6 billion Terafactory in Texas will become Tesla‘s flagship 4680 factory when operational later this year.
Bringing cell production in-house aligns with Elon Musk‘s comments around wanting to vertically control the "limiting factor" for growth. It also allows focusing fully on innovations optimizing cost efficiency and production volume.
4680 Dimensions
The 4680 cell format increased diameter to 46mm and height to 80mm. Compared to 2170, this boosted capacity to over 5X a standard 18650 cell.
The larger cell surface area improves heat transfer out of the cell. This enables faster charge rates as well as higher output density leveraging the enhanced thermal overhead.
4680 Chemistry
While Tesla cells have transitioned cathodes from NCA to NCM over time, 4680s remain on NCM chemistry for now. Further chemistry innovation remains a possibility once manufacturing matures according to Elon Musk.
For now, focus has been on innovating architecture, footprint and production process to build a foundation cell able to outclass incumbent formats on all key metrics simultaneously.
4680 Cell Key Attributes:
- Dimensions 46mm x 80mm
- Cathode Chemistry – Nickel Cobalt Manganese (NCM) currently
- Energy Density – Target is >300 Wh/kg
- Cycle Life – Target is 1500 cycles
- Models Used – Model Y currently. Future use cases like Cybertruck once production reaches scale.
| Output Metric | 18650 Cell | 2170 Cell | 4680 Cell |
|---|---|---|---|
| Diameter | 18 mm | 21 mm | 46 mm |
| Height | 65 mm | 70 mm | 80 mm |
| Capacity | 3.1 Ah | 4.9 Ah | 23 Ah |
| Cathode Chemistry | NCA | NCM | NCM (for now) |
| Charge Rate | 1C | 1C | 7C |
| Energy Density | 250 Wh/kg | 260 Wh/kg | 300+ Wh/kg (targeted) |
| Cycle Life | 1000 cycles | 1000 cycles | 1500 cycles (targeted) |
LFP Cells – Elevating Accessibility
Alongside bleeding edge 4680 development, Tesla is also now leveraging Lithium Iron Phosphate (LFP) cells targeted primarily at the Chinese EV market.
LFP Chemistry
LFP chemistry substitutes expensive Cobalt and Nickel metals used in NCM/NCA cathodes with more abundant Iron and Phosphates.
This transition reduces raw material costs significantly. However it also impacts energy density, which would reduce range if used in longer range premium models.
Battery Supply Localization
By localizing LFP cell production in China with CATL as the partner, Tesla can reduce costs of shorter range city cars. Reports indicate nearly 50% of Chinese made Model Y now utilize LFP batteries.
This allows Tesla to stretch accessibility goals in targeted regional markets like China without impacting gross margins. NCM cell supply is also freed up for export models favoring range.
Future Potential
LFP still makes up <5% of EV batteries globally today. However forecasts predict strong growth at 25%+ CAGR driven by Chinese market demand.
If manufacturing scales further and process innovations enhance LFP energy density, this alternate chemistry could become prevalent in shorter range segments worldwide widening adoption.
LFP Cell Key Attributes:
- Dimensions – Prismatic (large pouch cells)
- Cathode Chemistry – Lithium Iron Phosphate
- Energy Density – Lower (~160 Wh/kg currently)
- Cycle Life – Very High (2000 – 3000 cycles)
- Models Used – Chinese Made Model 3 and Model Y
| Output Metric | NCM Cells | LFP Cells |
|---|---|---|
| Cobalt Content | 8-12% | 0% |
| Nickel Content | 80-90% | 0% |
| Energy Density | 250-300 Wh/kg | 160-180 Wh/kg |
| Cycle Durability | 1000 cycles | 3000+ cycles |
| Raw Material Cost | Higher | Lower |
Tesla Cell Strategy Powers Energy Storage Breakthroughs
Tesla‘s leading battery capabilities also power its energy storage products from Powerwall to Megapack. Behind the scenes it is the same cell innovations accelerating electric transport that is transforming renewable energy viability and resilience worldwide.
Let‘s analyze key linkages between Tesla‘s vehicle battery advances and how this drives progress and cost efficiency in the storage domain.
Shared Battery Investment
Each dollar Tesla invests towards furthering cell R&D, refining manufacturing, expanding capacity and improving performance benefits both automotive and energy applications.
The table below overlays key shared focus areas that illustrate this technology leverage.
| Battery Innovation Driver | Transport Impact | Energy Impact |
|---|---|---|
| Faster charge acceptance | Enables faster DC fast charging | Supports surges from renewables |
| Higher power density | Unlocks vehicle performance | Reduces system footprint |
| Longer cycle life | Lengthens operational lifetime | Minimizes lifetime costs |
| Simplified manufacturing | Cuts production expenses | Lowers deployed system costs |
| Larger form factors | Boosts vehicle range | Grows storage capacity per install |
Investor confidence in Tesla‘s industry leading prowess to continue rapid battery innovations thus also boosts their energy storage play in tandem.
Vertical Integration
Tesla‘s new 4680 cell factory investments also continue to extend their vertical integration behind both batteries and overall storage systems.
Owning the full end-to-end value chain offers unique optimization opportunities around balancing cell production costs, vehicle demand and energy capacity needs holistically.
As stationary storage demand grows exponentially, Tesla is now uniquely positioning itself to reap maximum leverage by tailoring supply in tandem across transport and grid applications from shared core battery investments.
Comparing Tesla‘s Cell Chemistries
Each chemistry and form factor combination from Tesla offers differing blend of attributes. But exactly how do these compare numerically on key metrics?
The spider charts below visualize comparative data to highlight relative pros and cons across various dimensions. Higher values are better for each axis.
Cell Chemistry Comparison
- NCM and NCA cells offer highest energy density – important for long range EVs
- LFP EVs trail on energy density but excel on durability, safety and cost
- The 4680 cell aims to push the performance envelope further on all vectors
Cell Format Comparison
- The 4680 cell size increases capacity 5X+ over 18650 format
- Peak charge rate is also likely to increase with better thermal dynamics
- Being tabless, manufacturing cost is targeted to now be lower
So for both chemistry and physical form factors the 4680 cell aims for meaningful step function improvements rather than incremental enhancements.
Tesla‘s Continued Focus Driving Further Breakthroughs
Tesla‘s progress accelerating EV adoption has been remarkable already. Pivotal to this has been rapid battery innovation across multiple dimensions:
- Driving down cell cost via improved cathode chemistry
- Increasing cell capacity via larger form factors
- Reimagining cell architecture for better thermal dynamics and simplified manufacturing
And Tesla plans continued massive investments here including developing its own next generation cell manufacturing processes.
With Gigafactories enabling exponential scale matched to accelerating cell technology, Tesla seems poised to achieve its bold aim of reaching 20 million annual vehicle production in the coming decade.
The road has been exciting already since the original Roadster. And there remains massive scope to further optimize batteries to stretch viability and accessibility to even broader echelons globally.
