The solid-state battery is one of the most promising solutions for the future generation of batteries, with their high thermal stability making them significantly safer and longer-lasting than traditional electric vehicle batteries.
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All-solid-state batteries (SSBs) use solid electrolytes, a carbon-free anode, and a cathode composite layer. During charge or discharge, the ions migrate into the ionically conductive solid matrix rather than into the ionic salt dissolved in the solution.
Solid-state batteries store and distribute energy via redox reactions. The cathode undergoes reduction and the anode endures oxidation, allowing the battery to store and release energy as necessary.
How are All-Solid-State Batteries Different From Liquid Lithium-Ion Electric Vehicle Batteries?
Solid-state batteries employ a solid electrolyte consisting of glass, ceramics, solid polymers or sulfites, as opposed to the polymer gel or liquid electrolyte used in traditional lithium-ion batteries for electric vehicles (EVs).
Advantages of Solid-State Batteries
All-solid-state batteries promise greater energy storage density, increased reliability and wear resistance, fast charging, and, most importantly, improved operational safety. At high temperatures, liquid electrolytes become volatile and flammable. On the other hand, solid electrolytes have high thermal stability, which limits the risk of fire or explosion.
Solid-state batteries have a higher energy density per unit area due to their compact size. The energy density of a solid-state battery can be up to ten times greater than that of a lithium-ion battery of the same size.
Modern lithium-ion batteries for electric vehicles typically last between 2,000 and 3,000 cycles before showing noticeable degradation, whereas high-density solid-state batteries can approach 10,000 cycles.
Can Solid-State Batteries Eventually Replace Lithium-Ion in EVs?
Theoretically, solid-state batteries can replace Lithium-ion batteries in electric vehicles. BMW, Ford, Toyota, and Volkswagen are among the automakers that have already invested in this technology. However, solid-state battery cells are currently created in single copies in laboratories, and mass production is an expensive and underdeveloped process.
Lithium-ion batteries have dominated the market for the past three decades. However, their application in electric vehicles has some drawbacks. Lithium-ion electric vehicle batteries cannot be charged frequently; therefore, drivers are forced to travel on a single charge. Lithium-ion batteries can also spark a fire or explosion since they contain flammable liquid electrolytes.
On the other hand, solid-state batteries have much higher thermal stability, and they can store 50% more energy than lithium-ion batteries. Moreover, lithium-ion batteries rely significantly on nickel and cobalt, which are experiencing supply constraints and price increases.
EVs Manufacturers in Development of Solid-State Batteries
Nissan, Renault, and Mitsubishi have announced a combined investment of €23 billion in electric vehicles. In addition, the alliance intends to achieve widespread commercial manufacturing of all-solid-state batteries (SSB) by mid-2028.
The partners believe that the transition to all-solid-state batteries will equalize the costs of electric and conventional vehicles.
The Japanese manufacturer, Toyota, has been monitoring the solid-state battery industry for years and even holds the most patents for solid-state batteries. However, the largest automaker in the world upped the ante by declaring its commitment to invest more than $13.5 billion by 2030 in developing next-generation solid-state batteries.
Two years ago, Samsung introduced a high-performance and durable all-solid-state battery. The prototype battery can drive an electric vehicle up to 800 km on a single charge and has a lifespan of more than 1,000 charge cycles.
QuantumScape is considered a leader in the field of solid-state batteries. This corporation, located in San Jose, California, is supported by Volkswagen, Bill Gates and SAIC Motors.
QuantScape has already developed a solid-state battery that can charge from 0 to 80 percent in less than 15 minutes, whereas a Lithium-ion battery takes 60 minutes to charge from 10 to 80 percent. The energy density of these batteries is 80% higher than Lithium-ion batteries.
Research and Development in Solid-State Batteries
Pure Silicone Anode Solid-State Battery
Engineers at the University of California San Diego have partnered with LG Energy Solution to develop a new rechargeable solid-state battery. Scientists combined a solid-state sulfide electrolyte and a silicon anode in one device, completely abandoning lithium and carbon.
The battery proved its safety, durability and high energy intensity during tests. The prototype withstood 500 charge and discharge cycles, retaining 80% capacity at room temperature. The technology opens great prospects for electric transport, energy storage and other areas.
MIT's New Electrode Design
MIT researchers have developed mixed ion-electronic conductors (MIECs) as well as electronic and lithium-ion insulators. It is a 3D honeycomb architecture with nanoscale MIEC tubes. The tubes are filled with lithium, which forms the anode.
A key part of this discovery is that the honeycomb structure allows lithium to expand and contract during charging and discharging. This breathing of the anode avoids cracking the battery. The coating of the tubes acts as a barrier to protect them from the solid electrolyte. This solid-state battery arrangement prevents liquid or gel from injecting and consequently eliminates dendrites.
Future Outlooks for Solid-State Batteries
For some time, solid-state batteries have been seen as the next step in electric vehicle development. They are lighter, store more energy, and are less flammable than liquid ones. Until recently, two important obstacles remained - the cost and durability of such batteries.
Moreover, an inherent chemical defect exists in solid-state batteries. After several charge-discharge cycles, they begin degrading due to the buildup of lithium dendrites, which are tiny, twig-like lithium particles that grow and can penetrate the battery, leading to short circuits and other issues.
Once these issues are effectively addressed, a new battery revolution will certainly begin in the future.
References and Further Reading
Crawford, M. (2022). Solid-State Batteries Drive the Future of the EV Market. [Online] ASME. Available at: https://www.asme.org/topics-resources/content/solid-state-batteries-drive-the-future-of-the-ev-market (Accessed on 22 June 2022)
Rahardian, S., Budiman, B. A., Sambegoro, P. L., & Nurprasetio, I. P. (2019). Review of solid-state battery technology progress. In 2019 6th International Conference on Electric Vehicular Technology (ICEVT) (pp. 310-315). IEEE. https://doi.org/10.1109/ICEVT48285.2019.8993863
Sun, Y. K. (2020). Promising all-solid-state batteries for future electric vehicles. ACS Energy Letters, 5(10), 3221-3223. https://doi.org/10.1021/acsenergylett.0c01977
Tan, D. H., Chen, Y. T., Yang, H., Bao, W., Sreenarayanan, B., Doux, J. M., ... & Meng, Y. S. (2021). Carbon free high loading silicon anodes enabled by sulfide solid electrolytes for robust all solid-state batteries. arXiv preprint arXiv:2103.04230. https://doi.org/10.48550/arXiv.2103.04230
Verma, P. (2022). Inside the race for a car battery that charges fast — and won't catch fire. [Online] The Washington Post. Available at: https://www.washingtonpost.com/technology/2022/05/18/solid-state-batteries-electric-vehicles-race/ (Accessed on 22 June 2022)
Winton, N. (2022). Solid-State Batteries Promise Electric Car Popularity Boost, But Technical Mountains Await. [Online] Forbes. Available at: https://www.forbes.com/sites/neilwinton/2021/11/28/solid-state-batteries-promise-electric-car-popularity-boost-but-technical-mountains-await/ (Accessed on 22 June 2022)