A kind of electrochemical energy storage device and preparation method thereof

Abstract

The invention belongs to the technical field of electrochemical energy storage, and in particular relates to an electrochemical energy storage device: including a positive electrode sheet, a negative electrode sheet, a separator, an electrolyte and an outer package, the first Coulombic efficiency of the positive electrode active material on the positive electrode sheet is c%, and the unit The reversible capacity of the area positive electrode sheet is Cc mAh; the first coulombic efficiency of the negative active material on the negative electrode sheet is a%, the reversible capacity of the negative electrode sheet per unit area is Ca mAh, and the negative electrode capacity excess rate per unit area η=(Ca-Cc) / Cc ×100%; the electrode sheet has been treated with lithium-rich, and the lithium-rich capacity per unit area m is: Ca×(1-a%) / a%-Cc×(1-c%) / c%≤m. When the present invention is rich in lithium, the lithium-rich capacity m per unit area is: Ca×(1-a%) / a%-Cc×(1-c%) / c%≤m, which can ensure that the first lithium loss of the negative electrode is supplemented, There can also be excess lithium used to supplement the lithium consumption during the cycle, thereby improving the cycle performance of the battery.

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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