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

Abstract

The invention provides a lithium dendrite morphology growth prediction method and system based on a nonlinear phase field model. The lithium dendrite morphology growth prediction method comprises the steps: 1, deducing according to a free energy change rule and reaction kinetics to obtain a phase field variable control equation, a lithium ion concentration field control equation and a potential field control equation in a lithium dendrite growth process; 2, collecting parameters in the growth process of the lithium dendrites; 3, inputting the parameters and the equation into finite element simulation software, determining the size of an electrolyte region needing to be calculated, performing grid division, setting a boundary condition, an initial condition, a calculation step length and calculation time, and performing transient solution of a control equation set; 4, outputting the change conditions of the phase field variable values in the calculation process and the calculation region as images to obtain the growth morphology of the lithium dendrites on the surface of the negative electrode of the lithium battery in the charging process. According to the method, the problem that a solid-liquid interface needs to be tracked continuously in a traditional model is solved, the calculation complexity is reduced, and the calculation efficiency is improved.

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 ...

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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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