Electrochemical devices and electronic devices

Abstract

The application provides an electrochemical device and an electronic device, wherein an electrochemical device includes: a positive electrode, a negative electrode, a separator, and an electrolyte; the positive electrode includes: a positive electrode collector and a positive electrode disposed on at least one surface of the positive electrode collector Active material layer, the positive active material layer includes: positive active material, the volume of the positive active material layer is V1cm 3 , the true volume of the positive active material is V2cm 3 , 0.8≤V2 / V1≤0.92. In some embodiments of the present application, the positive electrode active material layer has a higher stacking efficiency and density, can store more energy under a certain volume, and reduces the infiltration space between the electrolyte and the positive electrode active material, thereby reducing the high voltage. The reaction between the cathode material and the electrolyte at high temperature can improve the cycle performance and low-temperature discharge performance of the electrochemical device at high voltage and high temperature.

Description

technical field [0001] The present application relates to the field of electrochemical technology, in particular to an electrochemical device and an electronic device. Background technique [0002] Electrochemical devices (such as lithium-ion batteries) are widely used in various fields. With the progress of society, people put forward higher requirements for the energy density of electrochemical devices. [0003] In some technologies, people try to increase the energy density of electrochemical devices by increasing the voltage to release more energy. However, electrochemical devices encounter a series of new technical bottlenecks under high voltage systems. The positive electrode material is cobalt acid Lithium-ion batteries are taken as an example. On the one hand, when the low-temperature discharge performance of the lithium-ion battery is excellent, the high-temperature cycle performance will decrease; when the high-temperature cycle performance is improved, the low-tem...

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Problems solved by technology

[0003] In some technologies, people try to increase the energy density of electrochemical devices by increasing the voltage to release more energy. However, electrochemical devices encounter a series of new technical bottlenecks under high voltage systems. The positive electrode material is cobalt acid Lithium-ion batteries are taken as an example. On the one hand, when the low-temperature discharge performance of the lithium-ion battery is excellent, the high-temperature cycle performance will decrease; when the high-temperature cycle performance is improved, the low-temperature discharge performance will decrease. Difficult balance between performance

On the other hand, under the high-voltage system, the surface of lithium cobaltate exhibits strong oxidation ability, and it is easy to react with the electrolyte, resulting in a poor interface relationship between the positive electrode active material and the electrolyte. When dealing with the problem of interface relationship , not only need to balance the discharge performance at low temperature, but also need to ensure the cycle performance at high temperature, the problem is not easy to solve

[0004] In some related technologies, the surface of the positive electrode active material is coated with metal oxide or other materials to try to solve the above problems, but the coated material will hinder the transmission of lithium ions to a certain extent, resulting in DC resistance (DCR, Directive Current Resistance) increases, the rate performance will also decrease, and the high and low temperature discharge performance of lithium-ion batteries will also cause degradation

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