Toyota Solid-State Battery: An In-depth Research Analysis

In September 2024, Toyota announced that the Japanese government had approved its plans to start building cars with solid-state batteries. This makes Toyota one of the first car manufacturers to launch an EV with all-solid-state batteries.

Toyota said it will begin solid-state battery production “starting from 2026” and will be “gradually implemented.” With its next-generation performance battery, it wants to reach an annual production target of 9 gigawatt-hours.

Solid-state batteries (SSBs) utilize solid electrolytes instead of the conventional liquid electrolytes found in lithium-ion batteries, offering several advantages, including enhanced safety, higher energy density, and improved longevity.

The inherent nonflammability of solid electrolytes significantly reduces the risk of battery fires, a critical concern in current lithium-ion technologies. This safety enhancement appeals to automotive manufacturers, aligning with the industry's push towards more reliable and durable energy storage solutions.

Toyota has announced plans to commercialize vehicles powered by solid-state batteries by 2027. It has been at the forefront of developing solid-state battery technology, poised to revolutionize the electric vehicle (EV) market.

And it takes 15+ years for Toyota to reach where it is today.

One and a Half Decade of Research and Development

In the mid-2000s, Toyota's initial interest in lithium batteries was low, and the company claimed that they would eventually be superseded by fuel cells. While fuel cell work continues, battery activity surged drastically in the 2010s.?

Toyota started researching solid-state batteries in 2010 and announced a four-layer all-solid-state battery in December 2010.?

Toyota confirmed that the prototyped all-solid-state battery can be used at 100°C. Existing lithium-ion rechargeable batteries with electrolytes cannot be used at this temperature because their electrolytes boil.

At the same time, Toyota was advancing Eco-Car Development With Electric and Hybrid vehicles. So, a safe and efficient battery was a challenge to overcome.

Toyota's foresight in recognizing the potential of solid-state batteries to revolutionize electric vehicles (EVs) by offering higher energy densities and safety profiles than traditional lithium-ion batteries is truly impressive. The company's aim to lead in this transformative area is a testament to its vision and commitment to innovation.

Toyota further sought partnerships with different research entities to speed up the research and development of SSBs. Over the years, the company overcame several challenges with successful partnerships to reach SSB commercialization sooner.?

After one year of development, Toyota and its research partners, involving Ryoji Kanno and his associate Masaaki Hirayama from Tokyo Tech, announced a breakthrough in SSBs.?

They developed the world’s first lithium superionic conductor, Li10GeP2S12, which demonstrated the capability to conduct lithium ions at room temperature more effectively in the solid state than in liquid. This new material doubled the conductivity of existing lithium-ion conductors and surpassed the ionic conductivity of the organic solvents used in current lithium-ion batteries.

The company devised a plan to commercialize this technology between 2015 and 2020.

As the research intensified, the company made plans to expand its EV market.

Battery technology was even included on MIT's list of the top 10 breakthrough technologies in 2011, encouraging other players to join the race.?

This was when many startups started to enter this technology to offer solutions to the challenges faced by Li-ion batteries.

In 2011, Toyota and Panasonic made a joint venture for battery development for EV and Hybrid cars.

Over the next two years, the company provided updates on battery chemistry refinement to improve its hybrid vehicles.?

In 2014, Toyota researchers announced a battery development and showcased its intentions to research lithium-air batteries.?

At the International Meeting on Lithium Batteries in Como, Italy, Dr. Hideki Iba from Toyota’s Battery Research Division and Dr. Chihiro Yada from Toyota Motor Europe’s Advanced Technology Group noted that, while lithium-air batteries may not be commercialized until 2030, solid-state batteries could be ready for the market as soon as 2020.

By 2014, the company had improved its battery technology 5X in power output compared to 2012. At that time, its solid-state battery had a power density of around 400 Wh/l (watt-hour per liter).

Meanwhile, Toyota also focused on hydrogen fuel cell technology and vehicles as it launched Mirai in Europe in 2015.?

As the race for solid-state batteries heated up, patent filings increased yearly. Even companies like Apple filed patents on batteries.?

2016 brought another breakthrough for Toyota and its research partners from the Tokyo Institute of Technology. The breakthrough was an improved design from its predecessor that was proven expensive, and some have exhibited problems with electrochemical stability.

The research highlighted lithium superionic conductors that exhibit exceptionally high conductivity (25 mS cm?1) and remarkable stability. These conductors, specifically Li9.54Si1.74P1.44S11.7Cl0.3, demonstrate near-zero voltage against lithium metal, indicating high stability.?

In 2017, Toyota claimed to work on new battery types that could hold a higher charge. The improved battery technology would allow the creation of smaller, more lightweight lithium-ion batteries for use in EVs.??

In May 2018, Toyota announced a new R&D program with Panasonic, Nissan, and Honda for solid-state battery development. The aim was to develop batteries with a range of upto 500 miles. The Japanese government was also a part of this program.

Despite all this research, the journey wasn’t always fruitful. The company faced several challenges, such as production hell and heating competition.

In 2018, Panasonic's CEO said the anticipated battery won’t be able to make it to production for another decade. This came from one of its partners and was a surprise.

Meanwhile, other automotive companies invested hundreds of millions in startups to gain a competitive advantage. For example, Volkswagen invested $100 million in Quantumspace, one of the top solid-state battery manufacturers .?

In 2019, Toyota announced that it would debut its solid-state battery EV in the Tokyo Olympics, but COVID-19 failed that plan.?

In 2020, Toyota established Prime Planet Energy & Solutions, Inc., a joint venture with Panasonic to develop automotive prismatic batteries. The joint venture will supply batteries not only to Toyota but broadly to all customers.

By 2021, Toyota had a portfolio of 1000+ patents in solid-state batteries alone and was leading the technology in patent count.

Toyota further announced an investment of $13.5 billion by 2030 in batteries, including solid-state batteries. It aimed to slash the cost of its batteries by 30% or more by improving the materials used and the structure of the cells.

"We are still searching for the best materials to use," Chief Technology Officer Masahiko Maeda.

In 2023, Toyota released its battery technology roadmap, which showcases that it won’t be able to release solid-state batteries before 2027.

The company further clarified that they will use these batteries on a hybrid vehicle first.

It's planning to sell 3.5 million EVs annually across 30 different Toyota and Lexus model lines by 2030. Long-range battery packs will provide up to 500 miles of range by 2026 and 620 miles by 2027.

Toyota aims to introduce solid-state batteries in 2027, which can recharge ultra-fast in 10 minutes from 10 to 80 percent charge.

Major Challenges in Solid-State Batteries

Toyota's pursuit of solid-state battery technology represents a significant advancement in the electric vehicle (EV) sector, but it is not without its challenges. Solid-state batteries possess several critical issues that must be addressed to ensure their practical application in automotive settings.

One of the primary challenges facing solid-state batteries is the interfacial stability between the solid electrolyte and the electrodes. High interfacial impedance is a significant barrier to the commercialization of SSBs, as it can lead to inefficient ion transport and reduced battery performance (Feng, 2024 ; Wang et al., 2020 ).?

The solid-solid contact necessary for effective ion conduction often increases resistance, severely limiting the battery's efficiency. This interfacial challenge is compounded by the mechanical and chemical instability that can occur at the electrode/electrolyte interface, which can lead to rapid capacity decay and failure of the battery (Liu, 2023 ; Chen et al., 2019 ).

Moreover, the mechanical properties of solid electrolytes present another hurdle. While solid electrolytes are generally more stable than their liquid counterparts, they can be brittle and susceptible to cracking under stress. This brittleness can lead to voids and cracks, further exacerbating interfacial issues and resulting in dendrite growth, potentially causing short circuits. Developing flexible and mechanically robust solid electrolytes is essential to mitigate these risks and improve the overall durability of solid-state batteries (Liu et al., 2020 ; Yang et al., 2021 ; Chen et al., 2019 ).

Temperature sensitivity is another significant concern for solid-state batteries. Polymer-based solid electrolytes, while offering some advantages, can suffer from performance degradation at elevated temperatures due to shrinkage and deformation. This sensitivity limits the operational temperature range of solid-state batteries, which is critical for automotive applications that require reliable performance across varying environmental conditions (Hu, 2024 ; Wang et al., 2020 ).

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