Toyota announces breakthrough in solid-state batteries

Arun Bhatia
4 min readAug 20, 2023
Image credit https://performancedrive.com.au/

Toyota has announced that it will be launching its first vehicle to use solid-state batteries by 2025. The first Toyotas to use the new batteries will be hybrids, rather than fully electric vehicles, making it possible the first to get the new battery could be the Prius. Toyota has made a breakthrough in battery technology that will allow it to eventually create batteries that offer a whopping 745 miles of range on a single charge — and that it’s aiming to create a battery that would give an electric car 900 miles of range1. Solid-state batteries are also much faster to charge — so you’ll spend less time waiting at electric car charging stations1. Toyota says that it has simplified the production of solid-state batteries, which could be a huge development for the vehicles they’ll power.

Solid-state batteries are a type of battery that use solid materials as both the electrodes and the electrolyte, instead of the liquid or polymer gel electrolytes found in conventional lithium-ion batteries. Solid-state batteries have several advantages over lithium-ion batteries, such as higher energy density, faster charging, longer cycle life, and improved safety. However, they also face some challenges, such as high manufacturing costs, low ionic conductivity, and interface instability.

To understand how solid-state batteries work, let us first review how lithium-ion batteries work. A lithium-ion battery consists of three main components: a positive electrode (cathode), a negative electrode (anode), and an electrolyte. The electrolyte is a liquid or gel that contains lithium ions that can move between the electrodes. When the battery is connected to a load, such as an electric vehicle or a mobile phone, an electrochemical reaction occurs at both electrodes. At the anode, lithium atoms release electrons and become lithium ions. The electrons flow through the external circuit to power the device, while the lithium ions migrate through the electrolyte to the cathode. At the cathode, lithium ions combine with electrons and other atoms to form compounds. This process is called discharge. When the battery is plugged into a charger, the opposite reaction occurs. The charger supplies electrons to the cathode, where they split the compounds and release lithium ions. The lithium ions then move through the electrolyte to the anode, where they combine with electrons and form lithium atoms. This process is called charge.

Image credit https://performancedrive.com.au/

A solid-state battery works in a similar way, except that it uses a solid electrolyte instead of a liquid or gel one. The solid electrolyte can be made of various materials, such as ceramics, polymers, or glass. The solid electrolyte must have high ionic conductivity, meaning that it can allow lithium ions to move easily through it. It must also have good mechanical stability, thermal stability, chemical stability, and compatibility with the electrodes. One of the main benefits of using a solid electrolyte is that it eliminates the risk of leakage or fire that can occur with liquid or gel electrolytes. Another benefit is that it enables the use of different electrode materials that can increase the energy density of the battery. For example, some solid-state batteries use lithium metal as the anode material, which has a much higher capacity than graphite or silicon used in conventional lithium-ion batteries. However, using lithium metal also poses some challenges, such as dendrite formation and volume expansion. Dendrites are needle-like structures that can grow on the surface of the lithium metal during charging and discharging cycles. They can pierce through the solid electrolyte and cause a short circuit or even an explosion. Volume expansion refers to the change in size of the lithium metal as it absorbs and releases lithium ions. This can cause mechanical stress and cracking in the solid electrolyte and reduce its performance.

Therefore, solid-state batteries are still under development and not widely available in the market yet. However, many researchers and companies like Toyota are working on improving their performance and reducing their costs. Solid-state batteries have the potential to revolutionize various applications that require high energy density and safety, such as electric vehicles, aerospace, medical devices, and wearable electronics.

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Arun Bhatia

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