Electrode and All-Solid-State Battery

An electrode comprising:

• a sulfide-based solid electrolyte;
• an electrolyte microparticle;
• and
• a composite particle, wherein
• the sulfide-based solid electrolyte includes S and P, has a PS4 crystalline phase, and has a molar ratio of the PS4 crystalline phase to a total amount of phases consisting of P and S of 60% or more,
• a ratio of a D50 of the electrolyte microparticle to a D50 of the sulfide-based solid electrolyte is 0.5 or less,
• the composite particle comprises an active material particle and a coating film covering at least part of a surface of the active material particle,
• the coating film includes a phosphorus compound,
• the phosphorus compound includes at least one of a first element and a second element as well as phosphorus, the first element is a glass network forming element, the second element is a transition element, and
• in the coating film, a relationship of the following expression (1) is satisfied:
• CLi(CP+CE1+CE2)≤2.5 (1)
• where
• each of CLi, CP, CE1, and CE2 represents an element concentration measured by X-ray photoelectron spectrometry,
• CLi represents an element concentration of lithium,
• CP represents an element concentration of phosphorus,
• CE1 represents an element concentration of the first element, and
• CE2 represents an element concentration of the second element.