Lithium ion battery

A lithium ion battery, comprising a positive electrode plate, a negative electrode plate and a separator, the positive electrode plate, the separator and the negative electrode plate being stacked successively and then wound from inside to outside;

• wherein the positive electrode plate comprises a positive electrode current collector, at least one functional surface of the positive electrode current collector is provided with a protective layer, a surface of the protective layer away from the positive electrode current collector is provided with a positive electrode active layer, and a length of the protective layer is greater than a length of the positive electrode active layer in a winding direction of the positive electrode current collector;
• wherein the at least one functional surface of the positive electrode current collector comprises an active layer region and further comprises a first end region and a second end region, and the first end region and the second end region are separately located at two ends of the active layer region;
• the protective layer comprises a conductive protective layer, the conductive protective layer is disposed on the first end region, the second end region and the active layer region, a surface of the conductive protective layer disposed on the active layer region away from the positive electrode current collector is provided with the positive electrode active layer;
• the protective layer comprises an inorganic filler, and a D50 of the inorganic filler is less than a D50 of an active substance in the positive electrode active layer;
• the first end region along the winding direction of the positive electrode current collector comprises a first flat region, an installation region, a second flat region, a third flat region and a first arc region, the installation region is provided with a positive battery tab, a surface of the positive electrode plate is pasted with a first taping, and the first taping is bonded with a surface of the protective layer disposed on the third flat region, a surface of the protective layer disposed on the first arc region and at least part of a surface of the positive electrode active layer disposed on the active layer region away from the positive electrode current collector.