QuantumScape Corporation has released performance data demonstrating that its latest technology in solid-state lithium-metal batteries addresses some of the fundamental issues holding back widespread adoption of high-energy-density solid-state batteries, including charge time (current density), cycle life, safety, and operating temperature. QuantumScape’s solid-state battery is designed to enable up to 80% longer range compared to today’s lithium-ion batteries.
QuantumScape’s newly-released results, based on testing of single-layer battery cells, show its solid-state separators are capable of working at very high rates of power, enabling a 15-minute charge to 80% capacity, faster than either conventional battery or alternative solid-state approaches are capable of delivering.
In addition, the data shows QuantumScape battery technology is capable of lasting hundreds of thousands of miles and is designed to operate at a wide range of temperatures, including results that show operation at -30 degrees Celsius.
The tested cells were large-area single-layer pouch cells in the target commercial form factor with zero excess lithium on the anode and thick cathodes (>3mAh/cm2), running at rates of one-hour charge and discharge (1C charge and 1C discharge) at 30 degrees Celsius. These tests demonstrated the robust performance of these single-layer pouch cells even at these high rates, resulting in a retained capacity of greater than 80% after 800 cycles (demonstrating high columbic efficiency of greater than 99.97%).
Beyond its ability to function at high rates of power while delivering high energy density, other key characteristics of QuantumScape’s solid-state lithium-metal battery technology include:
Zero excess lithium: In addition to eliminating the carbon or carbon/silicon anode, QuantumScape’s solid-state design further increases energy density because it uses no excess lithium on the anode. Some previous attempts at solid-state batteries used a lithium foil or other deposited-lithium anode, which reduces energy density.
Long life: Because it eliminates the side reaction between the liquid electrolyte and the carbon in the anode of conventional lithium-ion cells, QuantumScape’s battery technology is designed to last hundreds of thousands of miles of driving. Alternative solid-state approaches with a lithium metal anode typically have not demonstrated the ability to work reliably at close to room temperatures (30 degrees Celsius) with zero excess lithium at high current densities (>3mAh/cm2) for more than a few hundred cycles, and result in a short-circuit or capacity loss before the life target is met. By contrast, today’s test results show that QuantumScape’s battery technology is capable of running for over 800 cycles with greater than 80% capacity retention.
Low-temperature operation: QuantumScape’s solid-state separator is designed to operate at a wide range of temperatures, and it has been tested to -30 degrees Celsius, temperatures that render some other solid-state designs inoperable.
Safety: QuantumScape’s solid-state separator is noncombustible and isolates the anode from the cathode even at very high temperatures—much higher than conventional organic separators used in lithium-ion batteries.