Negative electrode current collector, negative electrode plate, electrochemical device, and apparatus

A negative electrode current collector, comprising a polymer material-based support layer and a copper-based conductive layer disposed on at least one surface of the support layer,

• wherein a thickness D1 of the copper-based conductive layer, a tensile strength T of the support layer, and a thickness D2 of the support layer satisfy a relational formula 1,
• 0.35
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• formula
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• 1
• in the formula 1, D1 and D2 are in the same unit, and T is in MPa;
• and
• in case of the negative electrode current collector where the copper-based conductive layers are disposed on two opposite surfaces of the support layer, the “thickness D1 of the copper-based conductive layer” refers to average thickness of the copper-based conductive layers on both sides of the support layer;
• and
• the tensile strength T of the support layer satisfies 200 MPa≤T≤300 MPa;
• and
• the thickness D2 of the support layer satisfies 1 μm≤D2≤20 μm,
• the thickness D1 of the copper-based conductive layer satisfies 1 μm≤D1≤2 μm, and
• the negative electrode current collector further comprising an upper protective layer and a lower protective layer, the upper protective layer has a thickness of denoted as Da and the lower protective layer has a thickness Db, and Da>Db, and 100 nm≤Da≤150 nm and 50 nm≤Db≤75 nm;
• and the upper protective layer comprises one or more of nickel and nickel oxide and the lower protective layer comprises nickel oxidekel;
• and the lower protective layer is disposed between the copper-based conductive layer and the support layer, and, the upper protective layer is disposed on a surface of the copper-based conductive layer away from the support layer.