Under the Skin: Solid State Batteries Could Be EV Gaming Levers Car News

So far, automakers have been a bit vague on the details of their EV batteries. At the cell level, most rely heavily on traditional cell suppliers, such as LG Chem or Sanyo, but Volkswagen recently presented detailed plans for the remainder of the decade until the switch to solid-state batteries after 2025.

Volkswagen is also moving away from the traditional battery concept, which involves assembling cells into modules, modules into battery, then the battery in the car. Considering the complexity of making batteries this way, it’s not a particularly flexible approach – although it might seem like it at first glance. Cars of different sizes will need different batteries, and even though the building blocks are the same, it still means differences, and differences mean more expense.

The next step in this process is a shift to what Volkswagen calls the “ Cell 2 Pack ” approach, which involves developing a standard cell that looks a bit like an old VHS video tape and packing it straight into the battery. . The third step will be “Cell 2 Car”, where the cells will be inserted directly into the battery container section of the chassis itself. Compiling battery cells in this way should make EVs faster, easier to manufacture, lighter, and cheaper by using a cell common to different models. This “Unified Cell Concept” will appear from 2030 using cells manufactured in the Group’s factories. The plan is to expand its use to 80% of the Volkswagen group’s range by 2030.

Beyond lithium-ion batteries, it is the semiconductor technology that the Group is developing with its partner Quantumscape, which announced in December that it had unraveled the secret of the production of a semiconductor separator (replacing the ‘liquid electrolyte in conventional batteries, hence’). The separator sits between the anode and cathode of a cell while still allowing lithium ions to pass through to charge and discharge.

The performance of conventional lithium-ion cells is limited by several factors. When a battery is charging, lithium ions travel from the cathode to the anode, which is made of carbon or a mixture of carbon and silicon. Carbon acts as a structure to contain lithium, but six carbon atoms are needed to contain one of lithium, and the materials themselves limit the rate of charging. When the battery discharges, the opposite happens and the ions travel through the liquid electrolyte to the cathode.

The ideal would be to use a lithium metal anode, which occupies a much smaller volume than carbon, but fast charging with a metal anode creates long metal tendrils, called dendrites, which run through the cell towards the cathode. When they finally do, they cause a short circuit. The ceramic-based separator of a solid-state battery blocks dendrites, allows the use of a lithium-metal anode and therefore the promised shift in charge speed. It also reduces weight and size and simplifies the manufacturing process.

Volkswagen sees the solid-state battery as the “ end game ” of battery technology, reducing charge time by 50% while increasing range by 30% at the same time. There is still a long way to go to industrialize the technology, but with it, an ID 4 Pro traveling 280 km could be recharged in 12 minutes, compared to 25 to 30 minutes today.

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