The drive to develop better electric vehicle battery technology that provides the power, range, and longevity of battery life and, at the same time, provides a cleaner alternative to gas-powered cars is more important than ever. Consumers demand better performing EVs that also are planet-friendly and safe. Government emission regulations throughout the world are increasingly putting pressure on automakers to produce less-polluting vehicles.
The challenge facing EV carmakers and battery manufacturers is that greener and safer do not necessarily translate to better performance. Currently, the maximum average distance an EV can reach on a full charge is 240 to 260 miles. The charging time is not any better.
Depending on the battery size and rate of charging; recharging time for an EV battery varies. The average charging time is 6 to 8 hours for a typical 60kWh electric car battery from zero to full charge. There are a few companies that claim to offer Fast Charging of 80% of the battery in 15 min, but these are not commercialized yet due to many issues including safety.
Better Battery Technology is Needed
In the past two decades, many approaches to developing a more powerful, cost-effective EV battery solution have mainly related to battery chemistry. But none has yet resulted in the step change needed to deliver an entirely usable electric car with performance equal to the combustion engine used in today’s mass-market with customers not ready to compromise on items such as range limitation.
However, new battery cell structure design incorporating smart 3D electrodes may be the game-changing component to addressing that challenge, as it offers to enhance EV battery performance overall.
The 3D cell architecture improves the surface area and properties of a battery’s electrodes and leads to improvements across multiple performance parameters, including extended driving range and faster charging times.
The Limitations of 2D Electrodes
Lithium-Ion (Li-ion) batteries with two-dimensional current collectors are currently the standard in the battery industry. However, this traditional structure, which hasn't been changed for 30 years, has some critical limitations. For example, temperature critically impacts the performance and longevity of lithium-ion batteries. Therefore, it is essential that heat distribution and dissipation in an EV, or any rechargeable battery, occurs evenly and quickly.
Current collectors enable the transfer of electrons between the anode and cathode and the external circuits, collecting the accumulated electrical energy. Achieving higher power and long-range use requires larger batteries to supply both the energy and power needed.
Subsequently, the battery becomes heavier and more expensive. However, increasing the ability of current collectors to transfer electrons enables this to be improved and tailored to meet the needs of customers.
Additional limitations with two-dimensional, planar current collectors involve excessive heat generation and uneven heat transfer. The current structure of 2D current collectors does not allow for fast and uniform heat dissipation that can lead to thermal runaway.
Increasing the size of 2D current collectors can help with heat dissipation but at the expense of battery power and cycle life. The opposite occurs when large amounts of active material are used with thin current collectors. This combination creates high energy cells but also at the expense of battery degradation.
3D Electrodes Technology a Game Changer for EV Batteries
The solution to developing EV batteries that provide optimum power, long-range performance, and charge quickly and safely is smart 3D current collectors.
A vital feature of the 3D electrodes structure is that it allows more significant loading of active material, enabling higher energy density, as opposed to the traditional 2D cell in which its planar structure limits the loading of active material. A three-dimensional structure increases the contact area between the electrodes and the current collector, like providing a highway for electron transport, thus increasing accessible energy capacity.
Lower internal resistance improves the transfer of electrons and reduces heat generation and propagation. Additionally, the 3D electrodes porous structure mitigates significant volume expansion of battery cells during the charging and discharging cycle. Not only does this improve mechanical stability, but the buffering ability of a 3D structure also provides a safer way to use utilize promising existing and emerging chemistries, such as silicon or others, to achieve higher energy density.
The combination of enhanced energy storage, improved conductivity, less heat generation, and material expansion translates into higher range, faster charging, and longer battery life.
All these benefits occur without materially changing the battery size or components. What’s more, any type of battery system can incorporate 3D electrodes, and it is possible to apply this 3D technology to tailor for battery needs.
A 3D current collector that is the same footprint size as a 2D current collector provides more power. Therefore, a battery built with 3D technology in this manner delivers better performance. The other way to see it is that a car manufacturer can use fewer batteries and to achieve the same performance. In this case, they are able to save space and weight and utilize the car space in a more efficient way. Furthermore, they save costs by utilizing fewer batteries or better batteries for their vehicles.
Cost-Effective Development of 3D Battery
While certain types of 3D metal structures are available in the market but at exceedingly high prices, and low control, as a result of complicated manufacturing processes that make them unsuitable for mass-market industries such as car manufacturing. Addionics is developing a novel method that can fabricate metal smart 3D structures in a controllable manner at a much lower cost while providing significant battery performance improvement. Being less expensive, they can be implemented in a wide range of markets, from consumer electronics to vehicles, and more.
Conclusion
Battery performance— range, charging time, and longevity— is critical to the continued adoption of electric vehicles. Current structures have significant shortcomings, regardless of the chemistry used. Smart 3D electrodes are a drop-in technology that promises to significantly improve performance while otherwise maintaining the existing framework and conforming to the chosen chemistry. As such, they are a critical tool in the next generation battery designer’s arsenal.
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