XLEX Batteries Pvt Ltd | May 27, 2025
As electric vehicles (EVs) scale globally, the design of battery packs is undergoing a silent revolution — led not just by chemistry, but by form factor. One of the most disruptive developments in recent years is the emergence of large-format cylindrical cells, commonly referred to as the 46XX cell family. This includes sizes such as 4680 (46×80 mm), 4690, and 4695, developed and refined by leading battery manufacturers and automakers.
At XLEX Batteries Pvt Ltd, we see these cells not as isolated improvements but as triggers for system-wide innovation. In this post, we break down how 46XX cells are reshaping the design, cooling, integration, and manufacturability of modern battery packs.
🧱 From Cell to Pack: Why 46XX is a Game Changer
The shift from smaller cylindrical formats like 21700 and 18650 to 46XX cells brings macro-level benefits that directly impact pack design efficiency:
🔹 Fewer Cells, Fewer Connections
- Traditional packs using 21700 cells may include 4,000–7,000 cells.
- A 46XX-based pack can deliver the same energy with under 1,000 cells.
- Fewer welds, lower complexity, and higher pack-level reliability are immediate outcomes.
🔹 Higher Packing Efficiency
Larger cells reduce dead space from cell holders, busbars, and interconnects. Engineers gain:
- Improved volumetric energy density at the pack level
- More room for thermal interfaces and insulation
🧊 Thermal Design: Cooling a Larger Beast
While 46XX cells store more energy, they also demand smarter thermal control. Their wider form introduces radial temperature gradients that smaller cells naturally avoid.
🔸 Challenges:
- Higher internal heat generation per cell
- Greater risk of localized hotspots
- Complex propagation behavior during abuse scenarios
🔸 Cooling Strategies Emerging with 46XX:
Cooling Method Notes
Bottom cooling Scalable but may struggle with radial uniformity
Side-contact cooling Adds complexity but improves radial extraction
Immersion cooling Ideal for 46XX due to full surface contact
At XLEX, we're actively developing pack layouts and simulation models to validate thermal behavior under extreme load cycles for 46XX cells.
🏗️ Enabling Structural Battery Pack Integration
The mechanical robustness of 46XX cells makes them suitable for load-bearing battery packs, enabling CTP (cell-to-pack) and structural integration:
- Tesla’s structural pack design leverages the rigidity of 4680 cells to form part of the chassis.
- At the system level, this results in:
- Reduced weight (fewer casings, mounts)
- Lower center of gravity
- Cost savings by eliminating redundant structures
At XLEX, we’re integrating this philosophy into our 14S2P prototype using 46XXs architecture in Gen2 packs.
🏭 Manufacturing, Welding & Assembly: What Changes?
🧪 Assembly Advantages:
- With fewer cells per pack, manufacturing cycle time per pack reduces.
- Tabless electrodes (in cells like 4680) reduce internal resistance and weld complexity.
- Automation is easier to scale with modular 46XX block assemblies.
🔧 Laser Welding Considerations:
- Larger current pathways demand wider busbars
- Cell expansion management (due to heating) must be designed into holders
- Force-controlled welding heads are necessary to prevent deformation during assembly
📊 Design Shifts in Pack Layouts
🧠 Final Reflections from XLEX
The rise of 46XX cylindrical cells is not just a trend — it’s a paradigm shift in battery system engineering. They force us to think beyond the cell: about how we manage heat, how we carry mechanical loads, how we scale production, and how we embed safety at every level.
At XLEX Batteries Pvt Ltd, our R&D roadmap is aligned with this direction. We’re investing in:
- Thermal simulation and pack optimization for large-format cylindricals
- Module-free pack concepts for lightweight two-wheelers and low-speed EVs
- Immersion cooling solutions tailored for radial heat dispersion in 46XX cells
The 46XX era is here — and it’s reshaping not just the cell, but the entire pack as a system.