San Jose, CA, October 24, 2024 – QuantumScape (NYSE: QS), a pioneer in solid-state lithium-metal batteries, has announced the successful production and shipment of its QSE-5 B-sample battery cells for testing by automotive clients. The QSE-5 represents a major step forward in battery technology, designed specifically to meet the rigorous demands of electric vehicles (EVs). This B-sample, rated at approximately 5 amp-hours, is QuantumScape’s first commercial cell format and combines high energy density with fast-charging capabilities to address the critical needs of the EV market.
The QSE-5 B-sample is designed to provide over 800 Wh/L in volumetric energy density and can charge from 10% to 80% in less than 15 minutes at room temperature, making it a standout product in the battery industry. “The QSE-5 B-sample is more than just a high-energy battery cell. It represents our commitment to innovation and our drive to set new standards in EV battery technology,” said Jagdeep Singh, CEO of QuantumScape. “Our goal with QSE-5 is to provide automotive OEMs with a cell that delivers both high performance and practical energy density, all while ensuring safety and durability.”
Energy Density: More Than a Simple Metric
One of the primary goals of the QSE-5 is to deliver optimal energy density. However, energy density is a complex metric influenced by many factors, making it challenging to compare across different battery types. The QSE-5 B-sample boasts a measured energy density of 844 Wh/L (volumetric) and 301 Wh/kg (gravimetric), based on real-world cell dimensions rather than theoretical projections. This distinction is critical, as many energy density figures reported in the industry are based on projections or calculations from smaller test samples that may not accurately scale up. QuantumScape’s approach uses actual physical cells to ensure realistic energy density expectations.
Additionally, QuantumScape clarifies that its QSE-5 energy density measurements are based on the fully packaged cell, including the necessary structure to contain the active materials. Many reported energy densities in the industry only consider the “active stack”—electrodes and separator layers—without accounting for the outer packaging. This full-cell approach gives customers a realistic sense of the energy density they can expect in actual use.
The cell design also excludes the tabbing area, which is usually included in module assembly, to ensure that the energy density calculations reflect the intended automotive application. Moreover, QSE-5 energy density metrics are reported at 100% state of charge (SoC), acknowledging the swelling that occurs in lithium-metal cells when fully charged, providing a clearer sense of performance in real-world scenarios.
Discharge Rate and Real-World Application
The QSE-5 B-sample was evaluated using a C/5 discharge rate, equivalent to a five-hour discharge that approximates a 350-mile drive at 70 miles per hour. This metric aligns closely with the needs of typical EV applications, making it highly relevant to automakers and consumers. Discharge rates are vital in assessing energy density because they influence the nominal capacity a cell can deliver in practical scenarios. A slower discharge rate can yield a seemingly higher energy density, but would not reflect the actual driving experience.
Some companies report energy density using a C/20 discharge rate, which would equate to driving at an impractical speed of 17.5 miles per hour. QuantumScape’s choice of C/5 provides a realistic benchmark that aligns with EV driving conditions and user expectations.
Impact of Temperature on Battery Performance
Battery performance, and particularly energy density, can vary significantly with temperature. Many solid-state technologies require elevated temperatures to deliver high energy density. However, QuantumScape’s QSE-5 B-sample achieves its 844 Wh/L energy density at a discharge temperature of 25°C (room temperature), making it suitable for passenger EV applications. This ambient-temperature performance is a notable achievement, given the tendency of many solid-state batteries to require elevated temperatures, making them less viable for everyday use.
Operating Pressure and Structural Efficiency
As with all lithium-based cells, the QSE-5 undergoes expansion and contraction during charge and discharge cycles. This effect is heightened in lithium-metal cells, and the compressive force on the QSE-5 remains below 3.4 atm to ensure safe and efficient operation. QuantumScape’s proprietary FlexFrame format—a hybrid design combining features of both prismatic and pouch formats—enables the QSE-5 to pack tightly alongside neighboring cells, maximizing volumetric efficiency. This feature is especially relevant for automotive applications, where space is a critical consideration.
In contrast to cylindrical formats, which may lose up to 9% of their energy density due to pack volume constraints, the FlexFrame design of the QSE-5 avoids these limitations, providing higher system-level energy density. As a result, automotive manufacturers can optimize the use of available space for battery modules, further enhancing vehicle range and efficiency.
Energy Density Checklist for QSE-5
QuantumScape provides a straightforward checklist for industry professionals to evaluate the energy density of the QSE-5 B-sample accurately:
| Checklist Item | QSE-5 B Sample |
|---|---|
| Measured vs. Projected Data | Measured figures |
| Fully Packaged Cell | Yes |
| Excluded Parts | Excluding tabbing area |
| State of Charge | 100% SoC |
| Discharge Rate | C/5 |
| Discharge Temperature | 25°C |
| Operating Pressure | < 3.4 atm |
| Cell Format | FlexFrame |
Conclusion
The QSE-5 B-sample represents a significant leap forward for QuantumScape and an important milestone in battery technology for electric vehicles. By optimizing energy density through detailed considerations of cell format, discharge rate, temperature, and operating pressure, QuantumScape is poised to meet the evolving demands of the EV industry. This innovation promises not only to improve battery performance but also to enable longer range and faster charging for electric vehicles, making the future of sustainable transportation more accessible to consumers.
