The adoption of electric vehicles and the continuous growth in the use of portable electronic devices are becoming increasingly relevant to solid batteries. Solid-state batteries rely on a solid electrolyte membrane with solid positive and negative electrode materials. To allow charge or discharge, ions travel through an ion-conductive solid matrix. Solid-state batteries are important because the solid electrolytes enable a few technologies that might make batteries more energy dense, which is necessary for modern electric vehicles to have greater range or last longer. While charging a regular lithium-ion battery, a reaction occurs between the liquid lithium salt electrolyte and the carbon electrode that forms a layer that helps protect the carbon and stops the two components from reacting further. This is called a solid electrolyte interface (SEI layer). This very thin and fragile layer mainly determines the battery’s durability.
Tokyo Tech scientists addressed one of the main disadvantages of all-solid-state batteries by developing low-resistance batteries at their electrode/solid electrolyte interface. While the devices they manufactured were promising and in some aspects, much better than conventional Li-ion batteries, the mechanism behind the reduced interface resistance was unclear. The buried interfaces in solid-state batteries could hardly be analyzed without damaging their layers. They suspected that crystallinity played a key role in the definition of interface resistance at the electrode-electrolyte interface. To prove this, two different all- solid- state batteries consisting of electrode and electrolyte layers were manufactured using a pulsed laser deposition technique. By using the X-ray crystal scattering test, scientists found crystallinity present at electrode-electrolyte in one of the batteries prepared with the help of the pulsed laser deposition technique. From these results, the team concluded that a highly crystalline electrode-electrolyte interface actually produced low interface resistance and a high-performance battery.
IMEC, one of the leading R&D and innovation hubs has prepared a prototype battery using solid nanocomposite electrolyte having a capacity of the high conductivity of up to 10 mS/cm and is likely to increase this capacity in future. The prototype battery procured a density of 200 Wh/liter of volumetric energy at a speed of 0.5C. Li-ion has still untapped the potential for further improvements in performance and cost reduction—a solid-state battery must be benchmarked with a moving target. Major manufacturing companies are working toward large scale commercialization of solid-state batteries, which will further boost the market for these batteries in the coming days.