Exploring the Potential of Solid-State Batteries for Tomorrow’s Solutions
There has been a notable surge in interest, particularly in the electric vehicle (EV) industry, in the advancement of solid-state batteries as a potential replacement for the existing lithium-ion technologies constrained by their limited capacity, long charging times, and the risk of potential fires.
Solid-state batteries are claimed to be smaller and lighter, yet more powerful and safer compared to lithium-ion batteries. Toyota claimed that its solid-state batteries can achieve 1,200 km in a single charge, which is more than double its current EV range, and with a charging time of 10 minutes or less. By comparison, current Tesla Model Y has a maximum range of 330 miles (~531 km) and a charging time of 15 minutes.
Although not yet available commercially, solid-state batteries seem to be demonstrating potential for radically transforming the EV sector in the near future. In this article, we aim to evaluate this technology space to identify who is actively developing and innovating on solid-state batteries, understand any current limitations and challenges with the development and commercialisation of solid-state batteries and explore how solid-state batteries would be applied in the next 5 years.
What are solid-state batteries?
Batteries are composed of anode, cathode and electrolyte. Solid-state batteries work on the same principle but unlike lithium-ion batteries that use liquid electrolyte solution and a polymer separator to keep the anode and cathode from coming into direct contact, solid-state batteries use solid electrolyte which also works as a separator (see image below). Various materials are being tested for use as solid electrolytes, including polymers, oxides and sulphides.
Solid-state batteries are not new, solid electrolytes have been discovered in the 1800s by Michael Faraday and have been used in small electronic devices such as heart pacemakers and RFID tags. However, technology is still far away from large industrial scale use mainly due to the prohibitive cost of materials and complex assembly, making it challenging to produce economically.
Recently, there is great interest in exploring the use of solid-state batteries in EV to replace lithium-ion batteries. Once the solid-state battery technology reach commercialisation, it is anticipated that the technology would eventually find applications where fast charging is important such as mobile phones, computers, and potentially airplanes and ships as well due to the ability for solid-state batteries to hold much higher capacity compared to current lithium-ion technologies.
Why the interest in solid-state batteries?
Increased capacity with smaller battery design – The global push towards replacing current internal combustion engine vehicles (ICEV) with EVs as a strategy for decarbonising transportation will require EVs to offer similar mileage to ICEV in order to increase the adoption of EVs. This will need enhanced battery capacity which can be done by adding more batteries, however, this increases cost and takes up space in an EV. With solid-state batteries, energy density per unit area is higher therefore allowing smaller battery design and as there is no liquid electrolyte, there is no need to design for components to provide safety therefore saving more space and enabling more active materials to be added to further increase capacity.
Enhanced safety – As there is no need to use flammable liquid electrolyte, this reduces the risk of thermal runway. Even when damaged, solid-state batteries retain a solid structure hence there is no risk of catching fire.
Capability to operate in wider temperature range – Solid electrolytes are not flammable and have higher thermal stability therefore enabling solid-state batteries to tolerate higher temperature conditions.
Faster charging: The ability of solid-state batteries to withstand higher temperatures also mean that they could be charged much quicker than current lithium-ion batteries (i.e. the faster a battery charges, the more it heats up).
Flexibility in shape – There is structural limitations with lithium-ion batteries as there is a need to prevent liquid leakage with the use of liquid electrolytes. However, there is no such restriction with the use of solid electrolytes therefore allowing more freedom in the shape and design of batteries.
As a result, Patent activity in the space has risen rapidly in the past 5 years demonstrating significant interest to innovate on solid-state batteries. A similar trend is also seen with scientific literature where a 2020 report from the Faraday Institution presented a chart showing the increasing number of literature publications with the keyword “solid-state electrolyte”, with tenfold rise in the space over the past two decades, and this publication activity can be seen to have risen significantly in the last 5 years or so.
Who is developing solid-state batteries?
Many automotive companies have invested in the development of solid-state batteries, with Toyota seen to be leading in the space with the aim to start manufacturing solid-state batteries for cars by 2027/2028 while Nissan and Honda have their own research programmes. Other automakers are collaborating with external battery manufacturers. For example, Ford and BMW invested in Colorado-based SolidPower that develops sulphide solid electrolyte. Mercedes-Benz, Stellantis, and Hyundai Motor Company have entered into joint development agreements with Boston-based Factorial Energy with its Factorial Electrolyte System Technology (FEST®) which combines a lithium-metal anode, quasi-solid electrolyte technology, and a high-capacity cathode. Mercedes-Benz have also entered into technology cooperation agreement in 2022 with Taiwan-based ProLogium who offers oxide ceramic electrolyte solid-state batteries. And Volkswagen is a strategic investor, joint-venture partner and has board representation in Californian-based QuantumScape, who is developing a patented solid ceramic electrolyte separator.
NASA also has a research project called Solid-state Architecture Batteries for Enhanced Rechargeability and Safety (SABERS), that looks at developing sulphur-selenium solid-state batteries for use in aircraft. They have developed a prototype sulphur selenium battery that produces 500 watt-hours of energy per kilogram of battery, said to be double the energy density of a standard lithium-ion battery with capability to withstand temperatures twice as hot as lithium-ion batteries.
Current challenges & limitations
Cost is a main challenge with solid-state batteries as the materials used for making solid-state batteries are more expensive and at the moment, manufacturing process is still rather complex.
Scaling up has always been the major obstacle in the production of solid-state batteries. The layers of cathode-anode cells need to be stacked quickly and with high precision without damaging the materials. Toyota claimed to have addressed this issue and is increasingly confident that they are able to stack the cells at the same rate as lithium-ion batteries.
It is also important for electrodes and electrolyte to maintain close contact and while this is easier using liquid electrolyte, this is more challenging with solid electrolyte.
The more common solid electrolyte being developed currently is based on sulfides which are very sensitive to moisture and will degenerate even when exposed to moisture in air. This means that the production process require very strict control of moisture, therefore needing dedicated facilities such as dry rooms, further complicating assembly which leads to increase in cost.
Repeated charge-discharge cycles can also cause formation of dendrites which can lead to cracking (i.e. filaments of lithium metal that crack through the ceramic electrolyte) hence significantly limiting the lifetime of solid-state batteries. “Dendrite cracks initiate when lithium accumulates in sub-surface pores. When the pores become full, further charging of the battery increases the pressure, leading to cracking”. Toyota have also claimed to solve this challenge using “a highly flexible, adhesive, and crack-resistant solid electrolyte,” created by combining material technologies from Toyota and its partner, Idemitsu Kosan.
Applications of solid-state batteries
Solid-state batteries are already being applied in niche electronics and medical implants currently and are expected to expand into consumer and/or portable electronics, EVs, energy storage once manufacturing obstacle can be overcome.
Ilika, based in the UK, is one example of a company that offers its Stereax miniature solid-state batteries for use in active medical implanted devices, small wearable and industrial IoT sensors. The company announced that it had successfully made its shipment of Stereax M300 batteries to its first customers in May 2023. Ilika is also working on its Goliath solid-state batteries composed of an oxide solid electrolyte and a silicon anode for electric vehicles and cordless consumer electronics.
Applications of solid-state batteries for EVs are still a few years away from commercialisation due to some of the challenges and/or limitations we mentioned. In Germany, solid-state batteries have already been installed in city buses with Mercedes-Benz already supplying over 20 eCitaro electric buses to Bremen’s public transport operator BSAG in 2021. These contain lithium-polymer battery with solid electrolyte from French-based Blue Solutions, a subsidiary of Bolloré. However, Blue Solutions’ solid-state batteries only offer a range of about 200 km and require operation at higher temperatures between 50-80°C. This could be one reason why Mercedes-Benz is seen to be moving away from using solid-state batteries in its electric buses. In a May 2023 article, it was reported that Mercedes-Benz is shifting towards Nickel-Manganese-Cobalt (NMC) batteries for its electric buses as the new third generation NMC technology can offer ample energy storage due to its improved cell chemistry and optimized battery package, enabling significant increase in energy density. This resulted in reduced demand for the use of solid-state batteries in their electric buses.
Conclusion
In order to power a decarbonised future and avoid the worst consequences of climate change transforming energy storage is essential. The Faraday Institution forecasted that solid-state batteries would find their first wave of applications through the 2020s into mass-market consumer electronics and wearables. Wave 2 and 3 would occur through the 2030’s and 2040’s when solid-state batteries become commercially viable in EVs.
Replacing century-old technology won’t happen overnight, but as an Open Innovation consultancy company Strategic Allies has an extensive experience in the global search for innovative technologies, solutions, products, strategic alliances and other new business generating opportunities. We work for a small portfolio of international manufacturing clients who are actively seeking novel technological solutions. Embracing all aspects of Open Innovation and often looking in places our manufacturing clients do not even know exist, we also understand the issues of confidentiality and sensitivity required to bring the right opportunities in what can often be disguised or complex situations. Together with our network of personally known facilitators, we have developed an energetic and tenacious approach valued by many clients across a wide spectrum of industry.
If you would like to hear more about our approach, please contact John Allies – john@strategicallies.co.uk. We are always happy to send you more details or schedule a call to discuss challenges, opportunities, and how we may be able to support you using our experience, knowledge and network.
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ProLogium and Mercedes-Benz entered into a technology cooperation agreement
ProLogium and MAHLE Sign MOU to Roll Out Solid-State Battery Solutions for EVs
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