Lithium battery and manufacturing method thereof

Abstract

The invention relates to a lithium battery and a manufacturing method thereof. The lithium battery comprises a positive plate, a negative plate, electrolyte and a diaphragm; the electrolyte contains a polymer and a lithium salt, the polymer is polycarbonate and / or polyether; and after at least one charge-discharge cycle, the concentration space gradient of the polymer in the electrolyte is gradually decreased along the direction from the positive electrode to the negative electrode, and the concentration space gradient of the lithium salt is gradually increased along the direction from the positive electrode to the negative electrode. The electrolyte disclosed by the invention contains the polycarbonate and / or polyether polymer and the lithium salt; and along with battery cycle, the concentration space gradient of the polymer is gradually reduced from the positive electrode to the negative electrode, and the concentration space gradient of the lithium salt is gradually increased from the positive electrode to the negative electrode, so that collapse of positive electrode material particles and formation of negative electrode lithium dendrites are avoided, the cycle life of the battery is prolonged.

Description

technical field [0001] The present disclosure relates to the field of lithium batteries, in particular, to a lithium battery and a manufacturing method thereof. Background technique [0002] In situ polymerization is one of the best ways to solve the interface problem and lithium dendrites in lithium batteries. In the prior art, in-situ polymerization is mostly carried out by coating a polymer electrolyte layer on the positive electrode and then adding a local super-concentrated electrolyte or simply using a local super-concentrated electrolyte. However, this kind of method makes the polymer electrolyte after in-situ polymerization not penetrate into the positive electrode well, but is mainly distributed on the battery separator, especially in the laminated battery, so the separator absorbs a large amount of liquid electrolyte monomer before polymerization, As a result, the polymerized polymer film is mainly covered on the separator, and the polymer film on the electrode su...

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Problems solved by technology

However, this kind of method makes the polymer electrolyte after in-situ polymerization not penetrate into the positive electrode well, but is mainly distributed on the battery separator, especially in the laminated battery, so the separator absorbs a large amount of liquid electrolyte monomer before polymerization, As a result, the polymerized polymer film is mainly covered on the separator, and the polymer film on the electrode surface is only a thin layer, which cannot protect the electrode well, causing the positive electrode of the battery to collapse during the lithium ion deintercalation process. The negative electrode of the battery is prone to lithium dendrites, which ultimately shortens the cycle life of the battery.

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