Characteristic Analysis of Single Particle Cathode Materials for Sulfide-Based All Solid State Batteries

All Solid State Batteries (ASSBs) have great attraction as next generation energy storage technology due to their nonflammable solid electrolytes (SE) and high energy density compare to commercial Li-ion batteries. However, there are still some issues that need to be addressed to move beyond lithium-ion batteries (LIB)..<br/>One of the troublesome challenges is the unstable contact between active material and SE. A typical cause of unstable interface contact is unwanted side reactions between active material and SE. In particular, among solid electrolytes, sulfide-based solid electrolytes with high reactivity and a narrow operating voltage accumulate ions and electrons at the interface in contact with the cathode active material, causing many side reactions. In order to prevent such a side reaction, there have been an efforts to such as coating the surface of the cathode material with stable polymer, metal oxide, and lithium metal oxide.<br/>Another cause of interfacial contact loss is volume change. Whether ASSB or LIB, volume changes occur due to intercalation and deintercalation of lithium in the active material. In particular, materials that achieve higher capacities have larger volume changes because more lithium is accommodated. For this reason, composite anodes containing high-nickel NCMs in ASSB exhibit rapid capacity decline because it is difficult to restore contact between the cathode and the electrolyte once separated. To suppress volume changes, various methods are used, such as controlling the shape of active materials, surface coating using hard materials, and improving the physical properties of solid electrolytes.<br/>Here, we adopt a method of strengthening physical properties of a material and suppress volume changes by growing a cathode active material as a single particle. The single particle cathode material was synthesized by growing the primary particles of the polycrystalline cathode precursor into large sizes. For performance comparison based on physical properties, poly and single particle cathode material is applied to a sulfide based ASSBs. The details will be discussed at the meeting.