All-solid-state batteries, which are safe because they use hard-to-burn solid electrolytes, are expected to replace existing batteries that use flammable liquid electrolytes such as lithium-ion batteries.However, the resistance (interface resistance) at the interface between the solid electrolyte and the electrode is large, and there is a problem in realizing high-speed charging.

　As a result of investigating the factors that increase the interfacial resistance of all-solid-state batteries, the researchers found that the interfacial resistance increases more than 10 times when the electrode material is exposed to the atmosphere and water vapor during the fabrication process.

　On the other hand, we have also found a method to improve the battery performance that has deteriorated due to this.When a deteriorated battery is heat-treated at about 150 ° C, the interfacial resistance is reduced to 1/10 or less of that before the heat treatment, and it is possible to regain the same resistance value as a battery manufactured without any exposure to the atmosphere or water vapor. I heard that I understood.

　Protons (hydrogen ions) are involved in this deterioration / recovery mechanism.Protons derived from water in the atmosphere and water vapor invade the inside of the electrode, which hinders the transport of lithium ions at the interface and causes an increase in interfacial resistance. However, when heat treatment is performed, the invading protons enter the solid electrolyte. It is said that it can move spontaneously, detach, and restore to a normal interface.

　The results of this research are a major step toward improving the performance of all-solid-state batteries, and are expected to be a breakthrough for practical use.

Paper information:[ACS Applied Materials & Interfaces] Drastic reduction of the solid electrolyte–electrode interface resistance via annealing in battery form