An electrode plate, comprising a current collector (10, 20), an electrode active material layer (11, 21) disposed on at least one surface of the current collector (10, 20), and an electrical connection member electrically connected to the current collector (10, 20), wherein the electrode active material layer (11, 21) is disposed on a main body portion of the current collector (10, 20) at a zone referred to as a film zone, the electrical connection member and the current collector (10, 20) are welded and connected at an edge of the current collector (10, 20) at a welding zone referred to as a transfer welding zone, and a transition zone of the current collector (10, 20) between the film zone and the transfer welding zone, coated with no electrode active material layer (11, 21), is referred to as an extension zone; the current collector (10, 20) comprises a support layer (101, 201) and a conductive layer (102, 202) disposed on at least one surface of the support layer (101, 201), a single-sided thickness D2 of the conductive layer (102, 202) satisfies: 30 nm ≤ D2 ≤ 2 μm, and the support layer (101, 201) is a polymer material layer or a polymer composite material layer; and the electrode plate further comprises an internal-short-circuit protection layer, and the internal-short-circuit protection layer is an organic insulation layer and covers the electrical connection member in the transfer welding zone and at least a part of the extension zone, wherein viewed in a width direction of a coated surface of the electrode plate, the electrode active material layer (11, 21) comprises 2n + 1 zones based on compacted density, and compacted density of a middle zone is greater than compacted density of zones on both sides, wherein n = 1, 2, or 3; and preferably, n = 1. the electrode active material layer (11, 21) is disposed on a main body portion of the current collector (10, 20) at a zone referred to as a film zone, the electrical connection member and the current collector (10, 20) are welded and connected at an edge of the current collector (10, 20) at a welding zone referred to as a transfer welding zone, and a transition zone of the current collector (10, 20) between the film zone and the transfer welding zone, coated with no electrode active material layer (11, 21), is referred to as an extension zone; the current collector (10, 20) comprises a support layer (101, 201) and a conductive layer (102, 202) disposed on at least one surface of the support layer (101, 201), a single-sided thickness D2 of the conductive layer (102, 202) satisfies: 30 nm ≤ D2 ≤ 2 μm, and the support layer (101, 201) is a polymer material layer or a polymer composite material layer; and the electrode plate further comprises an internal-short-circuit protection layer, and the internal-short-circuit protection layer is an organic insulation layer and covers the electrical connection member in the transfer welding zone and at least a part of the extension zone, wherein viewed in a width direction of a coated surface of the electrode plate, the electrode active material layer (11, 21) comprises 2n + 1 zones based on compacted density, and compacted density of a middle zone is greater than compacted density of zones on both sides, wherein n = 1, 2, or 3; and preferably, n = 1.