While we don’t have solid state batteries, electric cars have a problem. Despite the advances in lithium-ion batteries, the most widely used due to their good energy capacity, this is currently not enough to match what can be found in a gasoline tank, unless enormous weight is added to the vehicle.
A couple of examples: the Mercedes EQB batteries weigh 469 kg, almost 10 times more than a full tank, to certify 469 km of autonomy. One kilogram for every km you want to travel. If you are looking for performance, the ratio worsens: the 630 kg weight advertised by the Porsche Taycan batteries lasts at most 444 km before plugging it in again.
Additionally, lithium-ion batteries tend to degrade as they are charged. Those are some of the problems that solid-state batteries can solve.
What are solid state batteries?
Like lithium-ion batteries, solid-state batteries have a anode and a cathode, which are metal (or also composite material) electrodes that are immersed in a conductive liquid, the electrolyte. That is what we commonly call a cell and the set of cells forms a battery of greater or lesser capacity.
In a conventional lithium-ion battery the electrolyte is a lithium salt. It is what obtains the ions necessary for the reversible chemical reaction to occur between the cathode and the anode. In a solid state battery that electrolyte is a solid material.
The development of this type of battery was carried out by Nobel Prize winner in chemistry John B. Goodenough from the University of Austin (Texas, USA), who uses a crystal electrolyte in his research, although other researchers use other materials. .
5 benefits of solid state batteries
Solid-state batteries would erase in one fell swoop two limitations of conventional lithium-ion batteries: their limited autonomy and excessively long recharge times.
- Greater capacity: Having a solid electrolyte allows the use of an alkali metal anode on the negative side. This increases the charge density of the battery. Much more energy is stored in the same size and weight. How much? According to John Goodenough’s tests, up to three times more.
- Shorter recharge times: There is talk of times of less than an hour to fully recharge it. Although the charging capacities and power have not been made public, we could estimate the current charging times at one third, very low at the beginning and end of charging to safeguard the good condition of the battery,
- Greater reliability: The glass allows the battery to operate up to ambient temperatures of -20ºC (with current ones, performance drops greatly at low temperatures). Furthermore, as lithium-ion batteries complete charging cycles, the liquid solidifies with changes in temperature, passing between the anode and cathode separator, losing performance.
- Greater safety and useful life: When the electrolyte liquid solidifies, it forms dendrites (cavities) that break this separator and the battery loses performance. The solid electrolyte should act as a shield against the appearance of those dendrites that, in conventional batteries, cause overheating or even short circuits over time. Furthermore, in the event of an accident, a solid-state battery would not catch fire, something that can happen in the case of lithium-ion batteries, which forces manufacturers to thoroughly reinforce that area (adding more weight to the vehicle). . And in solid-state batteries, their electrolyte is not flammable.
- Less climate impact: Research by Transport & Environment indicates that this technology could reduce the carbon footprint by around 39%, compared to FFP (lithium ferrophosphate) or NMC-811 (nickel, manganese and cobalt). They could require more lithium (around 35% than a conventional lithium-ion, but much less graphite and cobalt are used. This lower use of materials (coupled with new mining methods with less impact) would reduce emissions to manufacture cars electrical.
- More economical: In line with the above, as indicated by Bloomberg NEF, solid-state batteries could have a cost around 40% of current ones. This information must be taken with caution since the calculations were made before the pandemic.
Types of solid state batteries
Currently there are two main types of solid state batteries, without a clear competitive advantage in each of them, since one stands out in one area and another in the opposite:
- Batteries with solid sulfur-based electrolyte: They have outstanding features, but they are less safe and their large-scale production is complicated.
- Batteries with solid polymer electrolyte: Easier to produce, they are stable but their performance is not as spectacular.
For now the complication occurs in the barrier between the electrode material and the electrolytes, known as the interface. Scientists are finding it difficult to ensure the rapid passage of ions between electrodes. Hence, new materials are sought with an ionic conductivity similar to that of a liquid electrolyte… and that is also viable for large-scale production. That brings us to a possible solution:
- Hybrid solid electrolyte batteries: They combine an inorganic and organic electrolyte, as studied at the Graz University of Technology. They combine ceramic electrolytes, which offer high conductivity and thermodynamic stability, and polymer electrolytes, which are easy to process, wanting to bring together the best of both materials.
When are solid state batteries?
The advancement of solid-state batteries is notable, but for now it has only been produced in the laboratory. It is still necessary to overcome some technical obstacles, such as the high temperatures required for them to function correctly or the durability of the solid electrolyte.
There is also a scalability problem: being able to industrialize the manufacturing process to produce them on a large scale. But car manufacturers are working hard on its development:
- Nio: The Chinese manufacturer dared to say that it will be able to offer this technology at the end of 2022, with 150 kWh of capacity together with WeLion, which has a factory in Zibo, in the Chinese province of Shandong. In 2024 they have a semi-solid battery which has already exceeded 1,000 km on a single charge in a real test on the road and in a few months it will begin mass production to be equipped in its top-of-the-range models.
- Ganfeng Lithium: The largest lithium producer in the world has already begun work on its solid-state battery factory, which will be the first in the world. It will produce 10 GWh per year and will include a research and development center.
- toyota: It is one of the brands that has made the most progress, in fact they planned to introduce a prototype with solid-state batteries at the Tokyo 2020 Olympic Games. They have a firm date for its arrival on the market in a mass-produced car: 2025. Of course, it seems that it will not be an electric one, but a hybrid, since the cost would be lower. Work on this technology together with panasonic through a joint venture and have already presented a prototype, the Toyota LQ Concept.
- Stellantis: They talk about 2026 as the year for the arrival of cars with solid state batteries. They have partnered with Mercedes-Benz in Factorial, which announces a volumetric energy density of 750,770 Wh/liter, with the goal of reaching 1,000 Wh/liter. A car like the Mercedes EQS has 550 Wh/liter, so you can see it in perspective.
- Renault-Nissan-Mitubishi: At Nissan’s Kanagawa facility (Yokohama, Japan) they have a small prototype production plant for laminated solid-state battery cells (ASSB). Your idea is to reach the market in 2028as they announced when presenting their long-term plan, Nissan Ambition 2030, in
- Volkswagen: He invested 300 million euros in the startup QuantumScape, which is researching this technology to be one of its largest shareholders. They have a prototype of a 10-layer battery, which charges up to 80% in 15 minutes and retains up to 80% of its capacity after 800 charge and discharge cycles.
- BMW and Ford: have invested in Solid Power, a company specializing in this type of batteries. They have a pilot production line in Colorado (USA) and this same 2022 the first batteries will reach manufacturers to test them in electric cars. The Bavarian manufacturer has already promised to launch a demonstration vehicle with solid-state batteries before 2025.
- Hyundai-Kia: The Korean company has ensured that we do not expect a car powered by this type of battery at least until 2030.
- SAIC: The owners, among others, of MG and Maxus assured at the beginning of 2024 that they aim to mount solid-state batteries very soon in their vehicles. They collaborate with QingTao Energy in the development of these batteries and it could be IM Motors (their premium brand) that releases them (it remains to be seen if they reach Europe).
Although the dates are relatively close, on the horizon of less than a decade, that does not mean that they will be imposed as soon as they reach the market. According to The Faraday Institution, an important battery research center in the United Kingdom, in By 2030, solid-state batteries will barely have a 4% share in the electric car market. And a decade later, in 2040, we will see them in one in three vehicles. Conventional lithium-ion batteries still have a way to go.
Of course, although technology and research provide solid-state batteries with enormous energy density in a small space, safe and quick to charge, a large charging network will be essential, well distributed throughout the territory and with powerful energy capacity to reduce the times with the car plugged in.
(NOTE: Information originally published on 9/20/2023, updated and expanded)
