Electrochemical energy storage device and preparation method hereof

Abstract

The invention belongs to the technical field of electrochemical energy storage, and particularly relates to an electrochemical energy storage device. The electrochemical energy storage device comprises a cathode plate, an anode plate, an isolating membrane, electrolyte and an outer package, wherein the initial coulomb efficiency of a cathode active substance on the cathode plate is c%; the reversible capacity of the cathode plate in unit area is Cc mAh; the initial coulomb efficiency of an anode active substance on the anode plate is a%; the reversible capacity of the anode plate in unit area is Ca mAh; the anode capacity excess rate eta in unit area is (Ca-Cc) / Cc*100%; electrode plates are subjected to lithium-rich treatment; and the lithium-rich capacity m in unit area is that: Ca*(1-a%) / a%-Cc*(1-c%) / c% is smaller than or equal to m. When lithium-rich treatment is carried out, the lithium-rich capacity m in unit area is that Ca*(1-a%) / a%-Cc*(1-c%) / c% is smaller than or equal to m; the first lithium loss of the anode can be supplemented; and excessive lithium can be used for supplementing lithium consumption in the cycling process, so that the cycle performance of the battery is improved.

Description

technical field [0001] The invention belongs to the technical field of electrochemical energy storage devices, in particular to an electrochemical energy storage device and a preparation method thereof. Background technique [0002] In 1991, Sony Corporation of Japan creatively adopted carbon materials as the anode material of lithium-ion batteries, which brought revolutionary changes in the field of lithium-ion batteries; And a lot of use on other portable electrical appliances. Lithium-ion batteries have many advantages, such as high voltage, small size, light weight, high specific capacity, no memory effect, no pollution, small self-discharge, long cycle life, etc. It is an ideal power source for mobile appliances and electric vehicles in the 21st century. Power supply and electric storage for storage power station. [0003] However, with the continuous development of miniaturization and long standby time of portable electronic devices, higher and higher requirements ar...

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Problems solved by technology

[0004] In order to achieve the purpose of improving the first Coulombic efficiency of the battery cell, experts at home and abroad have carried out extensive research and achieved some results: the Chinese patent application with the publication number CN1290209C mentions that lithium metal, negative electrode materials and non-aqueous liquids are mixed to form Slurry, coating the slurry on the current collector, and then drying the slurry; although this method can play the role of lithium supplementation, and finally improve the first Coulombic efficiency of the battery cell, the entire production process of the battery cell must be completed in a drying room. At the same time, it is difficult to blend lithium metal with the anode, so the production cost is high

The Japanese patent application with the application number JP1996027910 adopts the method of covering the surface of the negative electrode sheet with metal lithium sheet, then winding it to form a battery, and then pouring electrolyte solution; when using this method to replenish lithium, when the battery cell is assembled and formed, Lithium metal flakes are easy to pierce the separator and lead to a short circuit between cathode and anode. At the same time, because it is difficult to prepare thinner lithium metal flakes, the amount of lithium that the negative electrode can absorb is far less than that provided by the lithium metal flakes. There are problems such as lithium precipitation and poor cycle performance in the battery cell

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