Secondary battery electrode including mixture layer of double layer structure containing active materials of different particle diameters, and method for manufacturing the same

A method of manufacturing an electrode for a secondary battery, comprising:

• forming a lower mixture layer on one or both sides of a current collector layer, and including active material containing particles having diameters within a second particle diameter range and particles having diameters within a third particle diameter range;
• forming an upper mixture layer on the lower mixture layer, and including active material containing particles having diameter within a first particle diameter range and particles having diameter within the third particle diameter range;
• and
• rolling the electrode on which the lower and upper mixture layers are applied,
• wherein following conditions 1 and 2 are satisfied:
• D1>D2>D3 [Condition 1]
• D1−D3≥5 (μm) [Condition 2]
• wherein in the conditions 1 and 2,
• D1 is an average particle diameter of the particles having diameters within the first particle diameter range,
• D2 is an average particle diameter of the particles having diameters within the second particle diameter range, and
• D3 is an average particle diameter of the particles having diameters within the third particle diameter range,
• wherein in the upper mixture layer, a content ratio of the particles having diameters within the first particle diameter range to the particles having diameters within the third particle diameter range is in a range of 6:4 to 9:1 by weight, and
• a concentration of the particles having diameters within the first particle diameter range is higher in the upper mixture layer than in the lower mixture layer.

An electrode for a secondary battery, comprising:

• a current collector layer;
• a lower mixture layer disposed on one or both surfaces of the current collector layer and including a first active material;
• and
• an upper mixture layer disposed on a surface of the lower mixture layer which is opposite to a surface of the lower mixture layer that comes in contact with the current collector layer, and including a second active material;
• and
• a buffer layer interposed between the current collector layer and the lower mixture layer,
• wherein the buffer layer contains a niobium-containing oxide,
• wherein the second active material includes particles having diameters within a first particle diameter range and particles having diameters within a third particle diameter range,
• wherein the first active material includes particles having diameters within a second particle diameter range and particles having diameters within the third particle diameter range,
• wherein following conditions 1 and 2 are satisfied:
• D1>D2>D3 [Condition 1]
• D1−D3≥5 (μm) [Condition 2]
• wherein in the conditions 1 and 2,
• D1 is an average particle diameter of the particles having diameters within the first particle diameter range,
• D2 is an average particle diameter of the particles having diameters within the second particle diameter range, and
• D3 is an average particle diameter of the active material particles having diameters within the third particle diameter range, and
• wherein in the upper mixture layer, a content ratio of the particles having diameters within the first particle diameter range to the particles having diameters within the third particle diameter range is in a range of 6:4 to 9:1 by weight.