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Tesla’s next-gen 4680 battery is here, and Munro & Associates has torn it open to reveal its secrets. In this exclusive teardown of the Tesla Cybertruck’s 4680 cells, Sandy Munro and the Munro engineering team explore structural changes, chemistry upgrades, and major design shifts in Tesla’s Gen 2 battery architecture. For engineers, EV enthusiasts, and investors tracking battery innovation, this review offers an in-depth look into what Tesla’s been quietly refining—and how it may affect energy density, safety, and cost.
Evolution from Gen 1 to Gen 2: What’s Changed?
The teardown compares Tesla’s original 4680 cell used in the 2022 Model Y structural pack with the updated version found in the Cybertruck. While the two cells appear similar from the top, the changes underneath are significant. Gen 1 relied on a copper tab to connect the internal foils to the can, but Gen 2 eliminates this in favor of multiple direct welds through the end cap. This design simplification likely reduces manufacturing complexity and cost, while also creating more usable internal space—allowing for increased energy density.
Interestingly, two Gen 2 variants were observed: one with nine welds and another with twelve. While this may be a minor variation, it signals Tesla’s ongoing experimentation and possible refinement even within production batches.
Venting System Upgrades: Dual Protection
Safety improvements are evident in the redesigned venting system. The Gen 2 cell includes two distinct vent functions, both located at the bottom. The primary vent features a central ball bearing that ejects under pressure—a feature seen in competitor teardowns. However, Tesla has also integrated a reinforced perforated perimeter that acts as a secondary fail-safe vent if internal pressure isn’t adequately relieved by the first mechanism.
This dual-layer approach suggests Tesla anticipates high-energy events and has engineered the cells with multiple pressure relief options. It’s a strategic response to the challenges of battery thermal runaway and gas evacuation, especially critical in structural battery packs like the Cybertruck’s.
Chemistry Shifts: Toward Cobalt-Free, High-Nickel Cathodes
One of the most substantial changes lies in the chemical makeup. Gen 2 moves further away from cobalt, maintaining only trace amounts, and emphasizes nickel-dominant cathode material. Cobalt, while effective at fire suppression, is expensive and ethically controversial. Its reduction not only lowers cost but aligns with Tesla’s sustainability goals.
Manganese—typically the third component in nickel-manganese-cobalt (NMC) formulations—has also been removed. This could be linked to the dry-electrode process Tesla is pursuing, which was only partially achieved in Gen 1. Manganese may have interfered with the process or been harder to source reliably. The removal hints at significant process changes, possibly allowing dry-coating on both anode and cathode sides—potentially a game-changer for scaling and environmental impact.
Anode Innovation: Silicon Makes an Entrance
Tesla has long promised increased use of silicon in its anodes, and the Gen 2 cell delivers. Unlike Gen 1, where no silicon was detected, Gen 2 includes measurable silicon content. Silicon offers dramatically higher energy density compared to graphite alone, though it introduces challenges such as expansion and cycle degradation.
By integrating silicon—even in small amounts—Tesla is signaling confidence in their material engineering and binder formulations. This supports their claims of higher energy density and longer range, assuming durability can be maintained.
Structural Refinement: Flower Tabs and Jelly Rolls
Both generations of the 4680 cell use Tesla’s distinctive “flower tab” layout. Rather than relying on a single narrow tab, this design disperses current evenly through multiple connections, improving thermal performance and allowing faster charging. It’s part of Tesla’s effort to optimize power flow while minimizing localized heating—a must for high-performance EVs like the Cybertruck.
The “jelly roll” format remains, but subtle material changes exist. For instance, Gen 2 uses an aluminum foil substrate on the cathode and synthetic graphite on the anode. This isn’t revolutionary on its own, but paired with the flower tab structure and updated chemistry, it showcases Tesla’s systems-level design thinking.
Separator and Electrolyte: Stability in Familiarity
The separator—a critical safety component—remains largely unchanged between generations. It functions as a physical barrier between the cathode and anode while allowing ions to pass via the electrolyte. Its primary role is to prevent short circuits, and Tesla appears to be sticking with a proven design.
The electrolyte itself is still under analysis, though early indicators suggest there may be refinements in composition. If paired with a successful dry-electrode coating on both sides, the electrolyte could be a linchpin in enabling lower-cost, higher-efficiency manufacturing.
Challenges in Extraction and Testing
Teardown isn’t easy—especially when the cells are live. The Munro team notes that some Cybertruck cells arrived still charged, posing both safety risks and opportunities for live performance testing. Minor damage during extraction—like a dented bottom—can make them unsuitable for electrical analysis. Despite this, the team has successfully harvested intact cells and is preparing for full testing to validate Tesla’s energy density claims.
This meticulous care reflects the difficulty of working with advanced battery formats, but also the level of precision required to confirm Tesla’s engineering improvements.
Takeaways: What This Means for Tesla and the Industry
Tesla’s 4680 Gen 2 cell represents a meaningful leap in battery design. The combination of simplified internal architecture, reduced reliance on rare metals, and dual-layer safety venting highlights Tesla’s pursuit of scalable, safe, and high-performance EV batteries.
For engineers, the insights here underscore Tesla’s continued vertical integration and fast iteration. For investors and enthusiasts, it hints at upcoming advantages in range, safety, and cost—all critical metrics in EV competitiveness.
More importantly, the teardown suggests that Tesla is closing in on making dry-electrode manufacturing viable at scale. This could disrupt the industry by eliminating toxic solvents, reducing environmental impact, and slashing factory floor space requirements.
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