Electrochemical device

An electrochemical device, comprising

• a positive electrode, a negative electrode, a separator, and a lithium-ion conductive electrolyte, wherein
• the positive electrode includes a positive electrode current collector, and a positive electrode mixture layer which is supported on the positive electrode current collector and into which anions are reversibly doped,
• the negative electrode includes a negative electrode current collector, and a negative electrode mixture layer which is supported on the negative electrode current collector and into which lithium ions are reversibly doped,
• a length L1 of the negative electrode mixture layer in a first direction is longer than a length L2 in a second direction orthogonal to the first direction,
• a state of charge of two end regions adjacent to both ends of the negative electrode mixture layer in the second direction is X %,
• a state of charge of a center region of the negative electrode mixture layer in the second direction is Y %, and
• X<Y is satisfied.