Ultra-High-Power Lithium-Ion Battery for Aviation and Electric Vehicles
Amprius Technologies has announced the company’s latest high-performance battery solution, an ultra-high-power lithium-ion battery for next-generation aviation and electric vehicle applications.
Amprius Technologies has announced its latest lithium-ion battery solution capable of meeting the demanding weight to power emerging electric aviation and other e-mobility application requirements.
Construction of a silicon anode lithium-ion battery. Image used courtesy of Amprius
Based on the company’s silicon anode technology and advanced material system capabilities, the battery can deliver a discharge rate of 10 C with an energy density of 400 Wh/kg.
Along with EVs and other mobile platforms, one target application for the battery is next-generation aviation platforms like electric vertical takeoff and landing aircraft (eVTOL) and unmanned aerial vehicles (UAV).
The battery’s high power and lightweight combination will introduce new capabilities for these electric-powered aircraft through all phases of flight – take off, landing, and cruising.
Energy Density
The quest for more stored energy in smaller form factors, i.e., higher energy density, is never-ending for battery technology. And the progress always seems slower than what the market is demanding.
In the case of lithium-ion battery technologies, Amprius Technologies believes the limiting factor is simple chemistry. In conventional lithium-ion batteries, the anode is typically made of carbon in graphite. But this construction has reached its limits for power density.
In a rechargeable battery, like lithium-ion, the anode is the negative electrode through which current passes to and from the battery during charge/discharge cycles via the chemical oxidation/reduction process.
To get around the limitations of graphite, Amprius uses silicon as the anode material in its lithium-ion batteries, which can store up to 10 times more lithium ions than carbon, allowing for significantly more stored energy in a given volume.
Challenges with Silicon Anodes
In lithium-ion batteries, silicon anodes offer superior energy density, but the design is challenging. When charged with lithium, silicon anodes can experience significant swelling that can reduce battery cycles or even reliability issues like cracking.
The Amprius solution designs around these physical challenges to capitalize on superior performance. Rigorous testing, like the US Army Nail Penetration Test for military applications, helps demonstrate the reliability of Amprius’ battery design.
Nail penetration test for US Army applications. Image used courtesy of Amprius
Performance Advantages
The potential performance advantages of the higher energy density batteries are significant, resulting in up to 50% or more operating time/range for mobile/portable applications like EVTOLs, communication devices, and EVs.
Higher energy density extends operating time and range. Image used courtesy of Amprius
More Power for Vertical Take-Off and Landing
eVTOLs are emerging developmental aircraft that use electric propulsion rotors to take off and land vertically. Once airborne, the propellers can be rotated for horizontal flight.
For vertical take-off aircraft like eVTOLs and some UAVs, power requirements during take-off and landing are much higher than during normal flight operations.
In addition to a ten times improvement in energy density, the Amprius silicon anode battery also has higher power density, meaning more energy can be delivered to the load faster, a critical performance criterion for electric aircraft during vertical take-off and landing.
According to Amprius CEO Dr. Kang Sun, the new Amprius battery cells can deliver specific power performance that is 200% (3 times) higher than traditional graphite cells, and power delivery can be sustained through greater depths of the discharge cycle.
The Amprius cell has a power density of 3500 W/kg and a 10 C discharge rate. For a battery, the C rating measures how much discharge current the battery can deliver relative to its nominal capacity. A 10 C discharge rating means the battery can provide up to 10 times its rated power (at one hour) for short periods.
Vertical take-off and landing require more power. Image used courtesy of Amprius
Other Performance Specifications
In addition to high energy and power densities, the Amprius battery can charge quickly, reaching 80% capacity in less than 6 minutes.
The batteries have an operating temperature range of -30 to 55 °C.
