Electrochemical Supercapacitors for Energy Storage and Delivery

Fundamentals and Applications

Aiping Yu, Victor Chabot, Jiujun Zhang

• Publisher: CRC Press
• Year: 2017
• eBook ISBN: 9781351832830
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Energy

Although recognized as an important component of all energy storage and conversion technologies, electrochemical supercapacitators (ES) still face development challenges in order to reach their full potential. A thorough examination of development in the technology during the past decade, Electrochemical Supercapacitors for Energy Storage and Delivery: Fundamentals and Applications provides a comprehensive introduction to the ES from technical and practical aspects and crystallization of the technology, detailing the basics of ES as well as its components and characterization techniques.

The book illuminates the practical aspects of understanding and applying the technology within the industry and provides sufficient technical detail of newer materials being developed by experts in the field which may surface in the future. The book discusses the technical challenges and the practical limitations and their associated parameters in ES technology. It also covers the structure and options for device packaging and materials choices such as electrode materials, electrolyte, current collector, and sealants based on comparison of available data.

Supplying an in depth understanding of the components, design, and characterization of electrochemical supercapacitors, the book has wide-ranging appeal to industry experts and those new to the field. It can be used as a reference to apply to current work and a resource to foster ideas for new devices that will further the technology as it becomes a larger part of main stream energy storage.

1

Fundamentals of Electric Capacitors
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1.1 Introduction

An electric capacitor has a sandwich structure containing two conductive plates (normally made of metal) surrounding a dielectric or insulator as shown in Figure 1.1a. Common dielectrics include air, oiled paper, mica, glass, porcelain, or titanate. An external voltage difference is applied across the two plates, creating a charging process. During charging, the positive charges gradually accumulate on one plate (positive electrode) while the negative charges accumulate on the other plate (negative electrode). When the external voltage difference is removed, both the positive and negative charges remain at their corresponding electrodes. In this way, the capacitor plays a role in separating electrical charges. The voltage difference between the two electrodes is called the cell voltage of the capacitor. If these electrodes are connected using a conductive wire with or without a load, a discharging process occurs—the positive and negative charges will gradually combine through the wire. In this way, the capacitor plays a role for charge storage and delivery. Before we start a deeper discussion about capacitors, explanations of their history and some fundamental concepts may be useful.

1.1.1 History

Thales of Miletus, a philosopher, discovered electric charges when he rubbed amber with a cloth and observed magnetic particle attraction. Since then, the act of rubbing two non-conducting materials together to induce a charge has been treated as a demonstration of the triboelectric effect. In 1745, a better understanding of electrostatics and electrochemistry led to the invention of a condenser, as shown in Figure 1.1b. In the first condenser, two important factors determined charge separation and charge storage: the dielectric thickness and the surface area of the conductive materials. With technological advancements in materials and manufacturing, condensers evolved into modern capacitors that are now used in electrical systems.

Early capacitors were created from a Leyden jar as shown in Figure 1.1b. A capacitor consisted of a glass vessel whose interior and exterior were coated with metal foil. The foils acted as the electrodes and the jar acted as the dielectric. The foil coverings stopped before the jar’s mouth to prevent arc discharge. When capacitors became more prevalent in the twentieth century, their structures were designed to be more practical and economical in storing electrostatic charges as shown in Figure 1.1a. This structural change was very important after both world wars when demands for electronic parts increased. Capacitors were used in complex electronic systems, resulting in greater production and standardization programs to ensure the reliability and quality of the capacitors. Significant effort to meet quality and reliability requirements contributed to the successful improvements of modern electronics. Smaller and lighter capacitors possess greater capabilities and stability in adverse conditions and over wide temperature ranges.

FIGURE 1.1
(See color insert.) (a) Simplified schematic of capacitor design. (b) Cross-sectional schematic of Leyden jar (water-filled glass jar containing metal foil electrodes on its inner and outer surfaces, (denoted A and B).

This chapter reviews the fundamentals of capacitors and emphasizes the critical parameters of dielectric materials and the constructi...

Table of contents

• Cover
• Half Title
• Series Title Page
• Title Page
• Copyright Page
• Table of Contents
• Series Preface
• Preface
• Authors
• 1 Fundamentals of Electric Capacitors
• 2 Fundamentals of Electrochemical Double-Layer Supercapacitors
• 3 Fundamentals of Electrochemical Pseudocapacitors
• 4 Components and Materials for Electrochemical Supercapacitors
• 5 Electrochemical Supercapacitor Design, Fabrication, and Operation
• 6 Coupling with Batteries and Fuel Cells
• 7 Characterization and Diagnosis Techniques for Electrochemical Supercapacitors
• 8 Applications of Electrochemical Supercapacitors
• 9 Perspectives and Challenges
• Index