Solid-State Batteries: on the Road to a Miracle Battery
Author: Thorsten Rienth
Car manufacturers and specialized companies are investing hundreds of millions of euros in the development of solid-state batteries. With this new type of battery, they want to solve some of the fundamental disadvantages of the lithium-ion batteries still used in cars.
Longer ranges, shorter charging times, increased safety - that's what many electric car owners are hoping for. And it could come true in the foreseeable future. The development of solid-state batteries (SSB) is progressing rapidly: Toyota is planning to use solid-state batteries from 2027, Ford from 2028, Hyundai and Mercedes by 2030 and BMW from 2030. SSB cells are set to hit the market even earlier in the form of semi-solid concepts, giving electromobility a new boost.
Twice the energy density
But let's start from the beginning. The main difference to lithium-ion batteries (LIB), currently mainly used in cars, lies in the electrolyte. In conventional electricity storage systems, this medium for transporting ions between the anode and cathode is liquid. In solid-state batteries, it consists entirely of solids. Generally, they are developed on a sulfide, oxide, phosphate, polymer or ceramic basis.
Depending on the exact composition, electrolytes have different properties in terms of ionic conductivity, stability or weight - and therefore also in terms of energy density. Depending on the technology selected, SSB manufacturers are aiming for values of around 400 Wh/kg, according to a survey conducted by the Fraunhofer Institute for Systems and Innovation Research ISI in 2024. This would roughly double the energy density of lithium-ion battery cells (currently 150 to 200 Wh/kg). In turn, the 1,000-kilometer mark for electric cars would be within reach with the new wonder batteries.
1,000 charging cycles - some 500,000 kilometers driven
What's more, there are many indications that solid-state batteries are also significantly more durable. Last year, for example, Volkswagen and its US partner Quantumscape announced the completion of a solid-state battery prototype test. According to the results, it managed to complete more than 1,000 charging cycles, which corresponds to a total service life of around 500,000 kilometers driven. A second finding was also newsworthy: compared to the classic lithium-ion battery, this cell ages much more slowly. Following the tests, the battery still had a good 95 percent of its original storage capacity.
Another difference is relevant with regard to safety. “Liquid organic electrolytes are volatile, highly flammable and, in a worst case scenario, can accelerate fire or explosion events,” explains Thomas Hucke, Head of the DEKRA Battery Test Center being built at the site in Klettwitz, Brandenburg. Depending on the materials used, the following applies: “Solid electrolytes will significantly slow down the chemical reactions if push comes to shove.” Last but not least, the structure of electrode and electrolyte in very thin layers accelerates ion transport. The battery therefore charges faster.
Challenges until market launch
According to Hucke, it should only be a matter of time before the new generation of batteries is extensively installed in vehicles. "At the moment, the technology still sounds like a dream of the future. But it can quickly become reality." The basic findings on materials, material combinations and feasibility are already available. On a small laboratory scale, the state of development looks very promising. “The big challenge for manufacturers now is to first validate the new production steps and then scale them up - as well as establishing the necessary supply chains in parallel.”
A further obstacle is how the material behaves during operation. The anodes of solid-state batteries expand or shrink noticeably during the charging and discharging cycles. These effects must be taken into account in the design. Otherwise, contacts could be interrupted, or cracks could occur. Engineers must therefore find a way to ensure that the solid pairing of electrode and electrolyte remains functionally intact despite many charging cycles and wide temperature ranges.
Hucke estimates: “The year 2030 is quite realistic for the first commercial applications.” After that, things could move fast if price and performance are right. "The demand for electric cars with a significantly greater range definitely exists. And when a good product meets an unsaturated market, experience shows that things move very quickly."
Scenarios for use beyond the automotive industry
Meanwhile, Chinese e-car manufacturer Nio is taking an intermediate step by recently expanding the drive range of its ET7 flagship - using semi-solid-state battery technology. This is a hybrid battery that combines solid and liquid electrolyte materials.
But it is not just the automotive industry that is eyeing the new wonder batteries. Aircraft manufacturer Airbus has outlined the first sketches for a successor to the A320neo, which is set to enter the aviation market between 2035 and 2040. Solid-state batteries could not only help the aircraft taxi to the runway and from the runway to the parking position, but also provide the power for lighting and air conditioning in the cabin, which, similar to an alternator in a car, is currently still generated by generators in the engines. The solid-state battery is therefore also considered to have great potential as a stationary storage system for renewable energy.
The new
DEKRA Battery Test Center
at the DEKRA Lausitzring in Brandenburg is taking shape. It will offer all types of battery tests from a single source - including mechanical, performance and environmental tests alongside so-called ‘abuse tests’. DEKRA already provides comprehensive support for development assistance, approval and quality assurance through mechanical tests, performance and environmental tests and abuse tests for battery packs and modules. FInd out more here:
https://www.dekra.de/de/batterie-test-center/