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A Method to Predict Cycle Life of Li-ion Batteries

IP.com Disclosure Number: IPCOM000223242D
Publication Date: 2012-Nov-13
Document File: 3 page(s) / 90K

Publishing Venue

The IP.com Prior Art Database

Abstract

This disclosure discloses a practical method to predict cycle life of Li-ion batteries in battery storage station, where working conditions (rate of charge/discharge, depth of charge, ambient working temperature, etc.) are stable. It can provide a more reliable prediction of Li-ion battery cycle life by considering the influence of changeable working temperature caused by the increase of ohmic internal resistance of the battery.

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Page 01 of 3

A Method to Predict Cycle Life of Li-ion Batteries

At present, the famous methods for prediction of battery cycle life are Arrhenius method and Weibull distribution method. In the Arrhenius method, it is always difficult to estimate model parameters (i.e. activation energy), and the predicted battery cycle life is often shorter than its actual life. The Weibull distribution method uses a uniform model to describe the batteryperformance degradation though statistical inference, ignoring the influence of external conditions, such as ambient temperature. However, the battery performance degradation trend varies with different ambient temperatures.

In this case, a more practical and accurate method to predict battery cycle life considering changeable internal working temperature is needed.

Ohmic internal resistance is used to reflect the performance of Li-ion battery, it increases with the cycle time. The battery fails when its ohmic internal resistance beyond a predefined level.

The following figure shows the main procedure of the method disclosed in this disclosure:

Step 1: Obtain Ohmic internal resistance changing trend under different temperatures.

Ohmic internal resistance changing trend under different temperatures can be obtained through accelerated test, and an exponential function is always used to describe this trend.

Step 2: Predict the temperatures within the lifecyle of the battery.

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Page 02 of 3

The working temperature of Li-ion battery is mainly dete...