Lithium-Ion Battery Failures in Consumer Electronics For a listing of recent titles in the Artech House Power Engineering Library, turn to the back of this book. Lithium-Ion Battery Failures in Consumer Electronics Ashish Arora Sneha Arun Lele Noshirwan Medora Shukri Souri Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the U.S. Library of Congress. British Library Cataloguing in Publication Data A catalog record for this book is available from the British Library. ISBN-13: 978-1-63081-603-2 Cover design by John Gomes © 2019 Artech House 685 Canton Street Norwood, MA 02062 All rights reserved. Printed and bound in the United States of America. No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and re- trieval system, without permission in writing from the publisher. All terms mentioned in this book that are known to be trade- marks or service marks have been appropriately capitalized. Artech House cannot attest to the accuracy of this information. Use of a term in this book should not be regarded as affecting the validity of any trademark or service mark. 10 9 8 7 6 5 4 3 2 1 Contents Preface 13 1 Lithium-Ion Cells 17 1.1 Other Cell Chemistries 18 1.1.1 Lead Acid 19 1.1.2 NiCd 19 1.1.3 NiMH 19 1.2 Li-Ion Cell Operation 20 1.3 Li-Ion Cell Varieties 21 1.3.1 Cathode Materials 22 1.3.2 Anode Materials 23 1.3.3 Separator 24 1.3.4 Electrolytes 25 1.3.5 Current Collectors 25 1.3.6 Solid Electrolyte Interface Layer 25 1.4 Cell Construction 26 1.4.1 Prismatic Cells 26 1.4.2 Cylindrical Cells 26 5 6 Lithium-Ion Battery Failures in Consumer Electronics 1.4.3 Pouch Cells 27 1.5 Battery Management System for Li-Ion Cells 28 1.6 Charger Circuits for Li-Ion Cells 28 1.7 End of Life 29 1.8 Shelf Life 31 1.8.1 Life Test and Verification Process 32 1.9 Cycle Life 33 References 34 2 Overview of Li-Ion Battery Systems 37 2.1 Single-Cell Li-Ion Battery Systems 38 2.2 Multicell Li-Ion Battery Systems 41 2.2.1 Other Configurations 43 2.3 Automotive Battery Systems 43 2.4 Battery Systems for Large-Scale Energy Storage Systems 44 References 46 3 Power Supplies for Portable Consumer Electronic Products 47 3.1 Components of a Typical AC-DC Converter (AC Adapter) Circuit 48 3.2 AC Adapter Requirements 52 3.2.1 Propagating Circuit Board Failures 53 3.2.2 Burn Hazards 54 Contents 7 3.2.3 Component Derating 60 3.2.4 Power Supply Efficiency 63 3.2.5 Single Points of Failure 64 3.2.6 Power Supply Connectors 66 3.3 Adapter Specifications 67 3.4 Power Supply Construction and Assembly Issues 67 3.4.1 Input Power Connection 68 3.4.2 Electrolytic Capacitors 69 3.4.3 Mechanical Damage and Access to High Voltages 71 3.4.4 Creepage and Clearance Distances 71 3.4.5 Soldering/Contaminants and Other Assembly Issues 73 3.5 Testing AC Adapters 74 3.5.1 Electrical Characterization Tests 74 3.5.2 Thermal Characterization Tests 75 3.5.3 Mechanical Abuse Tests 76 3.5.4 Single Points of Failure Tests 76 3.6 DC-DC Converter Circuits 77 References 79 4 Li-Ion Battery Pack Charge Circuits 83 4.1 Charge Profile 84 4.2 Safety Timers 86 4.3 Battery Temperature Monitoring 87 4.3.1 Charging Li-Ion Cells at Low Temperatures 87 4.3.2 Charging Li-Ion Cells at High Temperatures 89 4.4 Battery ID 89 4.5 Charger Specifications and Requirements 90 8 Lithium-Ion Battery Failures in Consumer Electronics 4.6 Charger Circuit Construction and Assembly Issues 92 4.7 Testing Charger Circuits 93 4.8 Wireless Charger Circuits 98 References 100 5 Battery Protection Circuit Consideration 101 5.1 Need for a Protection Circuit 101 5.2 Single-Cell Battery Packs 106 5.3 Multicell Battery Packs 111 5.4 Large Battery Packs 115 5.5 Battery and PCM Specifications 116 5.6 PCM Design Review Tools 120 5.7 PCM Construction and Assembly Issues 121 5.7.1 Single-Cell Battery Packs 121 5.7.2 Multicell Battery Packs 122 5.8 Cell Failure Predictions 124 5.8.1 Cell Resistance as a Predictor of Failure 125 5.9 Testing PCMs 127 5.10 Summary 130 Appendix 5A: Electric Shock Hazards 130 References 134 6 Industry Standards and Testing 135 6.1 Commonly Used Standards to Contents 9 Evaluate Li-Ion Cells and Batteries in Portable Consumer Electronic Devices 135 6.1.1 UN Transportation Requirements 136 6.1.2 Underwriters Laboratories Testing Requirements 137 6.1.3 IEC Standards 143 6.1.4 IEEE Standards 145 6.1.5 Comparing Standards 145 6.2 Other Tests 146 6.2.1 Forced Internal Short-Circuit Test 146 6.2.2 Nail Penetration Test 149 6.2.3 Thermal Stability Test 150 6.2.4 Dent/Pinch Test 151 6.3 Predicting Li-ion Cell and Battery Shelf Life 151 6.3.1 Capacity Degradation 152 6.3.2 Calendar Aging 153 6.3.3 Fit Method 153 6.3.4 Time Dependence 154 6.3.5 Summary 155 Appendix 6A: International Organizations and Standards 155 Appendix 6B: Common Tests in Industry Standards 157 References 160 7 Physical Construction of Battery Packs 163 7.1 Single-Cell Battery Packs 164 7.1.1 Soldering of Cell Tabs 164 7.1.2 Routing of Battery Pack Wires 166 7.1.3 Cell Tab Insulation 167 7.1.4 Circuit Board Insulation and Mounting 168