QuantumScape starts testing ten-layered solid-state cells

Solid-state battery specialist and Volkswagen partner QuantumScape has announced the development of ten-layer battery cells in a recent quarterly report. The goal is to lead the new cells to similar capacity retention and cycling behaviour as the previous single- and four-layer cells.

In winter, QuantumScape published performance data on prototype cells for the first time and announced its intention to improve the range of electric cars by up to 80 per cent compared to today’s lithium-ion cells. Well-known investors are pushing the Americans’ technology development, including the Volkswagen Group, which now owns a third of the California-based company.

The results with single-layer pouch cells from December suggested that QuantumScape’s battery can be quickly charged to 80 per cent of capacity in 15 minutes. In addition, the developer promised a remaining battery capacity of more than 80 per cent after 800 cycles, which means that “hundreds of thousands of kilometres can be covered”. In addition, the solid-state battery is said to be extremely fireproof and to function on a broad temperature continuum without much drop in performance – even in cold temperatures of up to minus 30 degrees. Then, in the spring, QuantumScape announced it also had a four-layer version of the cell in development.

According to QuantumScape, it has succeeded in optimising the lithium metal solid-state battery through ten years of development work so that all aspects from high energy density, fast-charging capability and long service life to safety and realistic operating temperature are guaranteed. Until now, the low cycle stability has been considered a major weakness of solid-state batteries. The core of the QuantumScape technology is a ceramic separator, which is supposed to remedy exactly this. In addition, the solid-state battery does not have a classic anode. This is formed from pure lithium metal as soon as the battery is charged.

So much for the preface. In a quarterly report, QuantumScape now makes public that it is making progress with multi-layer cells. Specifically, the developer mentions a ten-layer battery cell in the 70×85 mm format already being tested. The report says: “These commercially relevant format cells are being tested at 1C and C/3 (one and three hour charge and discharge rates) under our standard temperatures (25 °C) and pressure (3.4 physical atmosphere) – conditions that we believe are relevant for automotive applications.”

QuantumScape aims to unveil its ten-layer solid-state batteries by the end of 2021, with improvements to be made before then. Cells with “several dozen layers” are to follow in 2022, followed by the production of test cells for electric vehicles in 2023. Then, with Volkswagen’s help, mass production of solid-state battery cells is to start in 2024 or 2025. The Wolfsburg-based company will then have the right to become the first buyer of the new batteries based on solid-state technology.

In parallel to the cell development, testing and production capacities are being built up: In February, QuantumScape announced the construction of a pilot plant called QS-0 in San José (California). At the end of March, QuantumScape announced in a share issue that it would also build a pilot plant with VW. A few weeks later, Volkswagen invested a further $100 million in the battery specialist, as QuantumScape’s cells had previously met contractually agreed requirements. According to a report from mid-May, the plant planned together with VW could be built in Salzgitter.

electrek.co, quantumscape.com (PDF)