Preface

Application fields of supercapacitors are expanding because they have a very large charge/discharge current density and a cycle durability of tens of thousands of cycles or more compared to secondary batteries. There are various kinds of supercapacitor: electric double layer capacitors with a relatively long history, pseudocapacitors that utilize electrochemical reactions, and the progress of hybrid capacitor technology that combines double layer capacity and electrochemical reactions. Development of electrode materials and electrolytes and new cell design for constructing devices support the performance improvement and expansion of new applied fields such as automobiles, heavy machinery, and energy harvesting. This book aims to provide engineers with the opportunity to review the latest information by integrating cutting-edge papers on the science, technology, and the application of supercapacitors.

The first chapter reviews the properties of carbon nanomaterials such as activated carbon, graphene, and carbon nanotubes. The author evaluates the current state of carbon nanomaterials and their composite materials for supercapacitor applications and describes future prospects (Khalid et al.). Chapters 2 and 3 focus on device flexibility and introduce the latest material technologies for developing wearable supercapacitors (Shanov et al.). In the fourth chapter, a constant voltage charge test is performed using a conventional electric double layer capacitor, and the relationship between the applied voltage and the deterioration behavior of the capacitor is considered from a practical point of view (Tashima). Chapter 5 explains the lithium doping method, which can increase cell capacity while maintaining the output and cycle characteristics of the capacitor. The author discusses the lithium ion hybrid capacitor, which has attracted attention in the field of capacitor technology (Sun et al.). In Chapters 6 and 7, two authors introduce high-capacity pseudocapacitors by using metal oxide nanomaterial and chromium nitride as electrode materials (Das et al. and Singh et al.). In the last chapter, the authors explain the application of supercapacitors to hybrid buses by drawing a realistic solution related to the controlling method for capacitor and power train based on precise energy efficiency calculation and simulation (Wang et al.).

**II**

**Section 2**

Application of Supercapacitors **115**

**Chapter 8 117**

Performance Evaluation and Control Strategy Comparison of

*by Enhua Wang, Minggao Ouyang, Fujun Zhang and Changlu Zhao*

Supercapacitors for a Hybrid Electric Vehicle

**Takaya Sato** National Institute of Technology, Tsuruoka College, Japan

**1**

Section 1

Science and Technology of

Supercapacitors
