Lithium dendrite growth prediction method and system based on nonlinear phase field model

Abstract

The present invention provides a method and system for predicting the growth of lithium dendrite morphology based on a nonlinear phase field model, including: step 1: deriving phase field variables during the growth of lithium dendrites according to the free energy variation law and reaction kinetics Governing equation, lithium ion concentration field governing equation and potential field governing equation; Step 2: Collect parameters during the growth of lithium dendrites; Step 3: Input parameters and equations into finite element simulation software to determine the electrolyte area to be calculated Size and mesh, set boundary conditions, initial conditions, calculation step size and calculation time, and perform transient solution of the control equations; Step 4: Output the calculation process and the changes of the phase field variable values ​​in the calculation area as an image , the growth morphology of lithium dendrites on the surface of the negative electrode of the lithium battery during the charging process was obtained. The invention solves the problem of continuously tracking the solid-liquid interface in the traditional model, reduces the computational complexity and improves the computational efficiency.

Description

technical field [0001] The invention relates to the field of lithium battery model technology and electric vehicle battery management technology, in particular to a method and system for predicting growth of lithium dendrite morphology based on a nonlinear phase field model. Background technique [0002] In recent years, due to the characteristics of high energy density, long service life, high rated voltage, and low self-discharge rate, lithium batteries have gradually become a research hotspot. Today, with the rapid development of electric vehicles, battery safety is restricting the development of electric vehicles. One of the major reasons is that in many electric vehicle fire and combustion accidents, battery thermal runaway is the primary cause, and there are various causes of battery thermal runaway, among which internal short circuit accounts for the largest proportion. During the long-term operation of lithium batteries, lithium dendrites are easy to be generated on ...

AI Technical Summary

Problems solved by technology

[0003] At present, there are few studies on the growth simulation of lithium dendrites, and the growth mechanism has not yet reached a unified conclusion. The existing commonly used model is the linear phase field model, that is, the change of the phase field is considered to be linearly proportional to the thermodynamic drive, and the solid region and The liquid area is calculated separately, and the solid-liquid interface is continuously tracked in real time to determine the calculation boundary. The calculation amount is very large and the time required is long

In addition, this linear phase field model is only applicable to the equilibrium or quasi-equilibrium state, and there is a large error when it is applied far from the equilibrium state. For example, when a large charging voltage is applied, the linear model cannot be applied well.

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