Method for speculating polymer lithium ion battery AC internal resistance

Abstract

The invention relates to a method for speculating the polymer lithium ion battery AC internal resistance. The AC internal resistance of the polymer lithium ion battery is set as the sum of the internal resistance of the positive and negative foils and the electrochemical internal resistance; an equivalent graph formed by a right triangle A, a parallelogram B and a right triangle C which are sequentially connected is built in the foil internal resistance; the internal resistance of the right triangle A part is shown in the description, the area of the right triangle C and the area of the righttriangle A are equal, and the internal resistance values are equal RC=RA; the internal resistance of the parallelogram B part is shown in the description, the internal resistance of the foil is R0=2*RA +RB; the calculation of the electrochemical internal resistance value can be carried out according to the Rct constant = Rct*S, and then the coating amount M is corrected, the electrochemical internal resistance formula is shown in the description, and the calculation formula of the AC internal resistance value of the polymer lithium ion battery is expressed as R=R0 positive + R0 negative + Rct.The method has the beneficial effects that the calculation method obtains the internal resistance value close to the actually measured value, the research on the mechanism performance of the lithiumion battery is facilitated, and more support is provided for the design of the battery.

Description

Technical field [0001] The invention belongs to the field of electrochemistry, and particularly relates to a method for estimating the AC internal resistance of a polymer lithium ion battery. Background technique [0002] Internal resistance is an important technical indicator to measure the performance of polymer lithium-ion batteries. Different types of batteries have different internal resistances. The same type of battery has different internal resistance due to inconsistent internal chemical characteristics. The internal resistance of the battery is very small, we generally use the unit of milliohm to define it. [0003] At present, the test method of AC internal resistance is: using the characteristics of the battery to be equivalent to an active resistance, give the battery a 1000Hz, 50mA constant current, and a series of processing such as voltage sampling, rectification and filtering to accurately measure its resistance The problem with this method lies in the need to d...

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Problems solved by technology

[0003] At present, the test method of AC internal resistance is: using the characteristics that the battery is equivalent to an active resistance, give the battery a constant current of 1000Hz, 50mA, and a series of processes such as voltage sampling, rectification and filtering to accurately measure its resistance value , the problem with this method is that it needs to directly test the battery

The method commonly used in the engineering application field is to roughly estimate the internal resistance of the battery according to the inverse proportional relationship between the internal resistance and the capacity, the accuracy is not high, and the error is large

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