What are the biggest challenges in switching to solid-state batteries? – Jalopnik

It’s been a bumpy road to the EV future so far, and automakers around the world are preparing for an “EV winter” of lower demand. However, there are also a few positive points that make the news, such as the fact that real solid-state batteries are getting closer to production. What’s the difference between these batteries and typical EV setups? An EV battery cell charges by splitting electrons from lithium atoms at the cathode and allowing the resulting lithium ions to travel through a separator to an anode, where they are reunited with electrons – which, because they couldn’t penetrate the separator, followed a different path through the charging circuit to get to the anode. Using that electricity to power the engine reverses the process, with the split-off electrons traveling in an external circuit to power a vehicle’s electric motor before rejoining the lithium ions.

In the traditional EV cell, there is also a liquid or gel electrolyte material around the electrodes and separator, and this is the stuff that the ions move through in the cell. A solid-state battery replaces the surrounding liquid electrolyte with a solid material that also acts as a separator. So the cell is like a piece of three-layer cake consisting of the anode, the electrolyte and the cathode.

Eliminating the highly flammable liquid, which can be difficult to contain during an accident, is one of the many benefits of solid-state batteries, but they also come with their own challenges. At this stage, engineers are still trying to figure out ways to reduce production prices, manage battery temperatures properly, maintain optimal ion flow, and prevent the lithium used from short-circuiting the battery. Let’s see how they’re doing.

One of the biggest problems with solid-state batteries is the same problem that has hindered the production of more traditional EV batteries: the cost of the raw materials needed to make them. Lithium is especially problematic here because – despite eliminating the lithium-containing electrolyte material – solid-state batteries can often use more of it in total. For example, a common way to increase the energy density in solid-state batteries is with a solid lithium anode. And according to Dr. Jordan Lindsay of the environmental consultancy Minviro, as reported in Motor trendsolid-state batteries could require five to ten times as much lithium as regular EV batteries. These will also not disappear immediately when solid-state batteries are introduced.

The result is that the demand for lithium for solid-state batteries must be added to the demand for lithium in other EV systems, driving prices up even further. While electric vehicle sales in the United States have certainly lost some momentum since the elimination of the federal tax credit, 2025 still saw the country’s second-highest annual EV sales ever, according to RMI. Moreover, sales of electric vehicles in China and Europe increased by 30% and 17% respectively last year. Then there’s the fact that lithium mining for electric vehicles could destroy the planet.

Due to factors like these, experts predict that lithium could rise to $28,000 per tonne by 2026. That compares with spot prices this summer in China – where the vast majority of the world’s lithium is processed – of about $8,300. However, new technologies are emerging, which some claim could reduce costs by 40% and also make extraction more environmentally friendly. Companies are working on various battery chemistries, such as sodium-sulfur setups.

Aside from the cost – both financial and otherwise – lithium is a concern because it can form dendrites. They’re a fairly common problem when you mix metals and electricity, because electric current causes atoms of the former to build up on the anode of an EV battery. During charging, the accumulation forms small, spiky, sometimes branched structures that grow toward the cathode. It is true that the separator is between the two electrodes, and that is partly to prevent the two from touching and shorting out. But the separator material is specifically designed to filter out the electrons and allow the lithium to pass through as part of the charge/discharge process. The lithium dendrites can grow from one electrode to the point where they penetrate the separator and come into contact with the other, causing a short circuit.

It’s essentially the same as when you short out your engine block heater. Electricity follows the path of least resistance, and in an EV battery that may mean electrons flow between the electrodes, along the dendrites, rather than following the longer circuit to run the EV motor. The resulting heat from the short circuit can lead to thermal flooding, igniting the liquid electrolyte and creating a fire that is difficult to extinguish.

Dendrites aren’t limited to lithium setups either: alternatives such as sodium ion solid-state batteries are lithium-free, but still run the risk of forming as a natural reaction to the electricity generation process. That said, scientists are making progress on the situation, with tailor-made production methods that help create a better, more uniform distribution of the sodium atoms, and this can indeed minimize dendrite growth while resisting corrosion.

Solid-state batteries can be significantly more expensive to produce for reasons other than lithium demand. It is relatively easy for electrons and ions to move through the electrolyte when they are essentially surrounded by the material in liquid or gel form, but engineers face some major obstacles with solid materials. These must be made to extremely close tolerances to ensure that the surfaces of the three layers of a solid-state battery – cathode-electrolyte-anode – make as close and consistent contact as possible. Furthermore, even if you could somehow ensure seamless contact, the boundaries between those layers can create areas of high resistance, making it harder for the lithium ions to get from one side to the other.

On the one hand, assembling solid-state batteries can be much faster than regular EV batteries, which can take weeks due to the difficult demands on the liquid electrolyte, and that should save costs. On the other hand, solid-state battery production is still a work in progress that will likely be expensive and time-consuming to perfect – and in some cases, invent.

Another production hurdle comes from the materials used as separators in solid-state batteries. They’re often made of ceramic, and – as we discovered when we looked at the differences between ceramic and steel bearings – that stuff can be extremely brittle and require special care to avoid cracking and breaking when the batteries are installed. Scientists are obviously working hard on solutions, ranging from separators made from sulfide and oxide-based materials to the use of custom additives designed to reduce the risk of cracking.

In general, batteries work best within a certain temperature range. If it’s too cold, the chemical reactions needed to generate electricity will slow down too much to be effective. If it’s too hot, the battery components can start to deteriorate. Automakers have developed a series of increasingly sophisticated thermal management systems over the years to help manage both situations, and while that experience should help refine solid-state battery technology, not everything will simply transfer over.

For example, one downside to eliminating the liquid electrolyte is that solid-state batteries can’t dissipate heat as quickly – and it doesn’t take much heat to degrade an EV battery. The so-called sweet spot for electric cars is between 60 and 80 degrees Fahrenheit, a temperature range not commonly seen in the United States. As it gets colder, the chemical reactions needed to produce electricity slow down, and battery components begin to break down more quickly as it gets warmer. There’s also the risk of thermal runaway – although these dangers can be somewhat mitigated by this “completely safe” EV battery ejection system.

Thermal management also plays a particularly important role in solid state batteries due to the contact problem we discussed above. Like most materials, the components in a solid-state battery can expand and contract as temperatures rise and fall. But because the battery materials differ from each other, the changes do not occur at the same time or to the same extent. This, in turn, makes it extra difficult to keep the surfaces of the electrodes and the separator in good contact with each other.