Post-Mortem Analysis of Inhomogeneous Induced Pressure on Commercial Lithium-Ion Pouch Cells and Their Effects

Georg Fuchs,Florian Ringbeck,Lisa Willenberg,Dirk Uwe Sauer

doi:10.3390/su11236738

Abstract

This work conducts a post-mortem analysis of a cycled commercial lithium-ion pouch cell under an induced inhomogeneous pressure by using a stainless-steel sphere as a force transmitter to induce an inhomogeneous pressure distribution on a cycled lithium-ion battery. After the cycling, a macroscopic and microscopic optical analysis of the active and passive materials was executed. Also, scanning electron microscopy was used to analyze active material particles. The sphere shape results in a heterogenic pressure distribution on the lithium-ion battery and induces a ring of locally high electrochemical activity, which leads to lithium plating. Furthermore, a surface layer found on the anode, which is a possible cause of electrolyte degradation at the particle–electrolyte interface. Significant deformation and destruction of particles by the local pressure was observed on the cathode. The analysis results validate previous simulations and theories regarding lithium plating on edge effects. These results show that pressure has a strong influence on electrolyte-soaked active materials.

Highlights

Today, lithium-ion batteries (LIBs) are omnipresent in everyday life
The sphere shape results in a heterogenic pressure distribution on the lithium-ion battery and induces a ring of locally high electrochemical activity, which leads to lithium plating
A sphere was used as a force transmitter to induce an inhomogeneous pressure distribution on a cycled LIB

Summary

Introduction

Lithium-ion batteries (LIBs) are omnipresent in everyday life. After their commercial introduction, LIBs have largely superseded other battery technologies due to their superior properties. LIBs have largely superseded other battery technologies due to their superior properties They are used in most portable devices such as mobile phones, smartwatches, cameras, laptops, e-cigarettes, and power tools. LIBs are increasingly penetrating the automotive market, where the battery is a crucial component for mobility. The battery cells of an electric car still account for the largest share of vehicle costs, and the lifetime and reliability of this component is essential. Previous work indicates that the design of a battery module consisting of several battery cells in terms of mechanical bracing is the crucial element of lifetime and reliability. Cannarella et al showed that too much initial pressure applied to LIBs decreases their lifetime due to closed pores in the separator, which causes undesirable degradation effects [1]

Methods

Results

Conclusion