Electrochemical element, method for producing same, and electrochemical device

An electrochemical element comprising a current collector, and an active material layer supported on the current collector, wherein

• the active material layer includes active material particles,
• the active material particles each include a lithium silicate composite particle including a lithium silicate phase and silicon particles dispersed in the lithium silicate phase, and a first coating that covers at least a portion of a surface of the lithium silicate composite particle,
• the first coating includes an oxide of a first element other than a non-metal element, and
• the active material layer has a thickness TA, and T1b<T1t is satisfied, where
• T1b is a thickness of the first coating that covers the lithium silicate composite particle at a position of 0.25TA from the surface of the current collector in the active material layer, and
• T1t is a thickness of the first coating that covers the lithium silicate composite particle at a position of 0.75TA from the surface of the current collector in the active material layer.