A solid-state battery is a device that transforms chemical energy into electrical energy by using a solid electrolyte to transfer lithium ions between electrodes. Unlike lithium-ion batteries, which use liquid or gel electrolytes, solid-state batteries consist of composite compounds with high ionic conductivity. This design provides several benefits, such as enhanced durability, higher energy capacity, quicker charging, extended lifespan, and versatile shapes.
Both solid-state and lithium-ion batteries feature a cathode and an anode, separated by an electrolyte that allows ion movement. As electrons flow from the cathode to the anode, the battery’s chemical potential energy increases, charging the battery. When electrons move back, this energy converts into electricity, which is discharged. The electrolyte inside balances the charge during these processes, making the battery rechargeable.
Solid-state batteries differ from lithium-ion ones primarily in their use of solid electrolytes like lithium phosphorus oxynitride (LiPON) instead of liquids or gels. Consequently, solid-state batteries don’t need an extra separator to prevent electrolyte mixing, as the solid electrolyte itself separates the poles.
There are several advantages of solid-state batteries over lithium-ion batteries. Solid electrolytes are less likely to catch fire, making solid-state batteries safer, especially in high-temperature environments. They also perform better in cold conditions since the ions in solid electrolytes move more consistently than in liquid or gel counterparts. Moreover, solid-state batteries can store more energy, powering devices longer or allowing for smaller, lighter batteries without sacrificing performance. Their design flexibility, free from leakage concerns, enables them to be made thinner, smaller, or even curved.
Solid-state batteries also degrade more slowly than lithium-ion batteries. While lithium-ion batteries have a limited number of charge cycles, solid-state batteries endure many more cycles, maintaining their capacity for a longer period. This longevity means solid-state batteries are more environmentally friendly, as they require fewer materials and produce less waste over time. Although their production demands more lithium, it uses less graphite and cobalt, materials associated with environmental harm like deforestation and pollution.
The concept of solid electrolytes dates back to the early 19th century when Michael Faraday discovered silver sulfide and lead fluoride. This discovery laid the foundation for solid-state ionics, the study of ion movement through solid electrolytes. Throughout the 20th century, research in this field grew, with significant developments like the discovery of beta-alumina in 1916 and the sodium sulfur battery by Ford Motor Company in 1966. These milestones, alongside the discovery of lithium salt-poly(ethylene oxide) complexes in the 1970s, significantly advanced solid-state battery technology.
In 1983, scientists at Oak Ridge National Laboratory developed lithium phosphorus oxynitride, leading to the creation of thin-film solid-state batteries. Continued research yielded solid-ion conductors with greater conductivity, culminating in the discovery of the lithium superionic conductor LGPS in 2011. This breakthrough allowed solid-state batteries to compete with lithium-ion batteries technologically. Since then, researchers and companies have been striving to create more powerful and cost-effective solid-state batteries, now commonly found in phones, computers, and cars.
Solid-state batteries represent a significant advancement over traditional lithium-ion batteries, offering numerous benefits such as improved safety, energy density, and longevity. Their development, rooted in early scientific discoveries, has evolved over centuries, leading to today’s sophisticated energy storage solutions.
Ilika plc (LON:IKA) is a pioneer in solid state battery technology enabling solutions for applications in Industrial IoT, MedTech, Electric Vehicles and Consumer Electronics.
