On the complex ageing characteristics of high-power LiFePO4/graphite battery cells cycled with high charge and discharge currents
Journal article, 2015

Li-ion batteries are known to undergo complex ageing processes, where the operating conditions have a profound and non-linear effect on both calendar life and cycle life. This is especially a challenge for the automotive industry, where the requirements on product lifetime and reliability are demanding. The aim of the present work is to quantify the ageing in terms of capacity fade and impedance growth as a function of operating conditions typical to high-power automotive applications; high charge and discharge rate, elevated temperatures and wide state-of-charge windows. The cycle life of 34 power-optimised LiFePO4/graphite cells was quantified by testing with charge and discharge rates between 1 and 4C-rate, temperatures between +23 °C and +53 °C, and a depth-of-discharge of either 100% or 60%. Although all cells show similar ageing pattern in general, the cycle life and the impedance growth is remarkably different for the tested cases. In addition, it is concluded that high charging rates, high temperatures or intensive cycling do not always lead to a shorter cycle life. One specifically interesting finding is that the combination of 1C-rate discharge in combination with 3.75C-rate charging was found to degrade the tested cells more rapidly than a symmetric cycle with 3.75C-rate in both directions.

Impedance spectroscopy

State-of-health

Fast charging

Cycle life

Lithium-ion battery

Battery ageing

Author

Jens Groot

Chalmers, Energy and Environment, Electric Power Engineering

Maciej Swierczynski

Ana Irina Stan

Sören Knudsen Kaer

Journal of Power Sources

0378-7753 (ISSN)

Vol. 286 475-487

Driving Forces

Sustainable development

Areas of Advance

Transport

Energy

Subject Categories

Other Chemical Engineering

Electrical Engineering, Electronic Engineering, Information Engineering

DOI

10.1016/j.jpowsour.2015.04.001

More information

Latest update

6/18/2018