The all-solid-state battery and its future in electric vehicles
The solid-state battery is one of the most promising solutions for the battery generation of the future, as its high thermal stability makes it significantly safer and more durable than conventional batteries for electric vehicles.
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All Solid State Batteries
All-solid-state batteries (SSBs) use solid electrolytes, a carbon-free anode, and a composite cathode layer. During charging or discharging, the ions migrate into the ionically conductive solid matrix and not into the ionic salt dissolved in solution.
Solid state batteries store and distribute energy via redox reactions. The cathode is reduced and the anode is oxidized, allowing the battery to store and release energy when needed.
How do all-solid-state batteries differ from liquid lithium-ion batteries for electric vehicles?
Solid-state batteries use a solid electrolyte composed of glass, ceramic, solid polymers, or sulphites, as opposed to the polymer gel or liquid electrolyte used in traditional lithium-ion electric vehicle (EV) batteries.
Advantages of solid state batteries
All-solid-state batteries promise higher energy storage densities, 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 higher than that of a lithium-ion battery of the same size.
Modern lithium-ion electric vehicle batteries typically last between 2,000 and 3,000 cycles before showing noticeable degradation, while high-density solid-state batteries can reach 10,000 cycles.
Eventually, can solid-state batteries replace lithium-ion in electric vehicles?
In theory, 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 manufactured in labs in one-off pieces, 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 disadvantages. Lithium-ion electric vehicle batteries cannot be charged frequently; Therefore, drivers are forced to travel on a single charge. Lithium-ion batteries can also cause a fire or explosion because they contain flammable liquid electrolyte.
On the other hand, solid state batteries have much higher thermal stability and can store 50% more energy than lithium-ion batteries. In addition, lithium-ion batteries are heavily dependent on nickel and cobalt, which suffer from supply shortages and price increases.
Electric vehicle manufacturers in the development of solid state batteries
Nissan Renault Mitsubishi
Nissan, Renault and Mitsubishi have announced a joint investment of 23 billion euros in electric vehicles. In addition, the alliance aims to achieve widespread commercial manufacturing of all-solid-state batteries (SSB) by mid-2028.
The partners believe that the transition to pure solid-state batteries will equalize the costs of electric and conventional vehicles.
Japanese manufacturer Toyota has been observing the solid-state battery industry for years and even holds the most patents for solid-state batteries. But the world’s largest automaker upped the ante by pledging to invest more than $13.5 billion in the development of next-generation solid-state batteries by 2030.
Two years ago, Samsung introduced a powerful and long-lasting 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 recognized as a leader in the field of solid state batteries. Based in San Jose, California, this company is backed by Volkswagen, Bill Gates and SAIC Motors.
QuantScape has already developed a solid-state battery that can be charged from 0 to 80 percent in less than 15 minutes, while a lithium-ion battery takes 60 minutes to be charged 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
Solid state battery with pure silicon anode
Engineers from the University of California San Diego have teamed up with LG Energy Solution to develop a new solid-state rechargeable battery. The scientists combined a solid-state sulfide electrolyte and a silicon anode in one device, completely eliminating lithium and carbon.
The battery proved its safety, durability and high energy intensity in tests. The prototype survived 500 charge and discharge cycles and retained 80% of its capacity at room temperature. The technology opens up great perspectives for electric mobility, energy storage and other areas.
MIT’s new electrode design
MIT researchers have developed mixed ion electronic conductors (MIECs) and 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.
An important part of this discovery is that the honeycomb structure allows the 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 injection and consequently eliminates dendrites.
Future prospects for solid state batteries
Solid-state batteries have been considered the next step in electric vehicle development for some time. They are lighter, store more energy and are less flammable than liquid ones. Until recently, two major obstacles remained – the cost and durability of such batteries.
In addition, an inherent chemical defect exists in solid-state batteries. After several charge-discharge cycles, they begin to degrade due to the accumulation of lithium dendrites, which are tiny, branch-like lithium particles that can grow and invade the battery, causing short circuits and other problems.
Once these issues are effectively addressed, a new battery revolution will surely begin in the future.
References and further reading
Crawford, M. (2022). Solid state batteries define the future of the EV market. [Online] LIKE ME. Available at: https://www.asme.org/topics-resources/content/solid-state-batteries-drive-the-future-of-the-ev-market (Accessed June 22, 2022)
Rahardian, S., Budiman, BA, Sambegoro, PL, & Nurprasetio, IP (2019). Overview of the advancement of solid state battery technology. in the 2019 6th International Electric Vehicle Technology Conference (ICEVT) (pp. 310-315). IEEE. https://doi.org/10.1109/ICEVT48285.2019.8993863
Sun, YK (2020). Promising solid state batteries for future electric vehicles. ACS energy letters, 5(10), 3221-3223. https://doi.org/10.1021/acsenergylett.0c01977
Tan DH, Chen YT, Yang H, Bao W, Sreenarayanan B, Doux JM, … & Meng YS (2021). High-charge, carbon-free silicon anodes enabled by solid sulfide electrolytes for rugged all-solid-state batteries. arXiv form arXiv:2103.04230. https://doi.org/10.48550/arXiv.2103.04230
Verma, P. (2022). Inside The race for a car battery that charges quickly – and doesn’t burn. [Online] The Washington Post. Available at: https://www.washingtonpost.com/technology/2022/05/18/solid-state-batteries-electric-vehicles-race/ (Accessed June 22, 2022)
Winton, N. (2022). Solid-state batteries promise to boost the popularity of electric cars, 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 at June 22, 2022)