Composite current collector, electrode sheet, battery, and electrical device

A composite current collector, comprising:

• an insulating substrate;
• and
• a conductive layer;
• wherein the conductive layer is disposed on both sides of the insulating substrate in a thickness direction of the insulating substrate;
• in a direction perpendicular to a thickness of the composite current collector, the composite current collector comprises an active material support region and a tab connection region, a thickness of the insulating substrate of the tab connection region is less than that of the insulating substrate of the active material support region;
• and a thickness of a conductive layer of the tab connection region is greater than that of a conductive layer of the active material support region;
• a thickness of the insulating substrate of the tab connection region is D3 and a thickness of the conductive layer of the tab connection region is D4;
• and a ratio of D4 to D3 is A, where 1≤A≤2;
• and
• the insulating substrate comprises a conductive material, and based on mass percent, a ratio of the conductive material is 3%-10% of the mass of the insulating substrate.