Positive electrode sheet and its preparation method and energy storage device

Abstract

The invention provides a positive electrode sheet and a preparation method thereof, and an energy storage apparatus. The positive electrode sheet comprises an aluminum foil and a positive electrode film sheet, wherein the positive electrode film sheet is arranged on the surface of the aluminum foil and contains a positive electrode active material, an aluminum oxide layer is formed on the surface,close to the positive electrode film sheet, of the aluminum foil in situ, and the thickness of the aluminum oxide layer is more than or equal to 150 nm and is less than or equal to 400 nm. In the positive electrode sheet, the aluminum oxide layer can prevent the positive electrode sheet from the mechanical property loss caused by the damage under the high compaction density so as to effectively increase the energy density of the energy storage apparatus, and further has functions of insulating and heat insulation so as to effectively improve the safety performance of the energy storage apparatus.

Description

Technical field[0001]The invention relates to the field of energy storage devices, in particular to a positive electrode sheet, a preparation method thereof, and an energy storage device.Background technique[0002]The vigorous development of power vehicles has attracted the attention of more and more consumers, and the requirements for secondary batteries for power vehicles have become more and more stringent. For example, it is required that the secondary battery must have a high capacity to meet sufficient cruising range, and the secondary battery must have superior safety performance so that consumers can use it with confidence. Therefore, in order to meet the development of secondary batteries to the power field, it is very important to solve the safety performance of high-capacity secondary batteries, and it is also the direction of joint efforts in the industry.[0003]In order to meet the high-capacity requirements of secondary batteries, the development of cathode materials wit...

AI Technical Summary

Problems solved by technology

However, the higher the nickel content of the positive electrode material, the worse its thermal stability and structural stability, resulting in greater challenges to the safety performance of secondary batteries.

When the compacted density of the positive electrode is greater than 4.0g / cm 3 , the damage of the positive electrode diaphragm to the aluminum foil of the positive electrode current collector will increase, resulting in changes in the mechanical properties of the positive electrode sheet, which in turn will reduce the safety performance of the secondary battery

For example, when the secondary battery is used at high temperature, due to the unstable structure of the positive electrode material at high temperature, a large number of side reactions with the electrolyte will cause thermal runaway, which may cause a risk of fire or explosion.

Another example is when the secondary battery is accidentally pierced, due to the deterioration of the mechanical properties of the positive electrode, the aluminum foil is easily short-circuited with the negative electrode, thereby generating a large amount of heat and causing the thermal runaway of the secondary battery, increasing the risk of fire or explosion

[0004] In the prior art, although the inorganic ceramic particle coating of the isolation film and the diaphragm layer can improve the safety performance of the secondary battery with a certain probability, it has the disadvantages of difficult coating and low efficiency, and leads to a decrease in the energy density of the secondary battery. Reduce heat dissipation performance; and coating inorganic ceramic particles can not fundamentally prevent short circuit between aluminum foil and negative electrode, so there are limitations to the improvement of the safety performance of secondary batteries

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