| CPC H01M 4/139 (2013.01) [H01M 4/623 (2013.01); H01M 4/625 (2013.01); H01M 10/0525 (2013.01); H01M 2004/021 (2013.01); H01M 2004/028 (2013.01)] | 18 Claims |

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1. An electrochemical device, comprising a cathode, wherein the cathode comprises:
a cathode current collector;
a first cathode active material layer comprising a first cathode active material; and
a second cathode active material layer comprising a second cathode active material, wherein the first cathode active material layer is disposed between the cathode current collector and the second cathode active material layer, and the first cathode active material layer is formed on at least one surface of the cathode current collector; and wherein the second cathode active material is embedded in the first cathode active material layer and forms a transition layer with the first cathode active material at an interface between the first cathode active material layer and the second cathode active material layer, and a thickness of the transition layer is less than a thickness of the second cathode active material layer;
wherein the first cathode active material layer comprises a first conductive agent, and a ratio of a specific surface area of the first conductive agent to a specific surface area of the first cathode active material is greater than or equal to about 1.3 and less than or equal to about 11; and
wherein the first cathode active material layer, the second cathode active material layer and the transition layer each comprise a binder, and a content of the binder of the transition layer is greater than a content of the binder of the first cathode active material layer and a content of the binder of the second cathode active material layer.
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