A kind of stepped current charging method that prevents lithium-ion battery negative electrode from decomposing lithium

Abstract

The invention relates to a stepped current charging method for preventing the negative electrode of a lithium ion battery from dissolving lithium, comprising: S1, adding a reference electrode to a commercial battery, making a three-electrode battery, and verifying the validity of the reference electrode; Capacity C0; S3. Determine the high-sensitivity model parameters of the three-electrode battery; S4. Establish a high-precision electrochemical model based on the high-sensitivity model parameters and model parameters obtained from manufacturers and literature, and determine the lithium analysis criterion formula; S5 . Changing the input conditions of the electrochemical model in step S4 to determine the maximum acceptable current meeting the lithium analysis criterion; S6. Taking 90% of the maximum acceptable current as the boundary current for charging control. The invention breaks through the traditional empirical selection, can effectively prevent the negative electrode from dissolving lithium, reduce the safety risk of lithium-ion batteries, improve charging efficiency, and provide important reference value for the field of optimized charging of lithium-ion batteries.

Description

technical field [0001] The invention belongs to the field of optimized charging of lithium ion batteries. Background technique [0002] Low temperature, high state-of-charge (SOC) and high-rate current will all induce lithium precipitation at the negative electrode of lithium-ion batteries. Lithium-ion batteries face problems such as difficulty in charging at low temperatures and easy lithium decomposition during charging, which seriously damages the driving range and safety of electric vehicles, and has constituted one of the limiting factors restricting the popularization of electric vehicles. How to quickly and safely charge the battery with electric energy under extremely cold conditions is one of the key technologies to promote the application of electric vehicles in cold regions. The charging current of the battery is very small, resulting in extremely slow charging speed at low temperature, and a slightly larger harmonic current may cause lithium deposition at the ne...

AI Technical Summary

Problems solved by technology

However, most of these methods are based on experience to set the charging current rate, which may lead to low charging efficiency or lithium deposition at the high SOC end, and it is difficult to directly apply the normal temperature charging method to low temperature charging, such as the CV charging method, when charging at a constant voltage at low temperature, The potential of the negative electrode is likely to be lower than the potential of lithium analysis, which will lead to the precipitation of lithium at the negative electrode

In addition, the battery dynamics are sluggish at low temperature, and the maximum charging current that the battery can accept is very small. When charging directly at room temperature at low temperature, the charging time will be very long, which is difficult to meet the actual needs of fast charging.

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