I want to thank Prof. Huang Zhigui (Southwest University) for his mentoring and support, especially during my most difficult days in college some 40 years ago. Happy 90th birthday, Prof. Huang!

It is my greatest honor to have had the support of the 2019 Nobel Laureate, Prof. M. Stanley Whittingham. I have received tremendous inspiration and great help from him during my entire scientific career; he not only invited me to compile two wide-ranging review articles on electrolytes for special issues of Chemical Reviews in 2004 and 2014, but also graciously agreed to write a Foreword for this book.

Also joining him to write Forewords for this book are three of my longstanding friends, Prof. Khalil Amine (Argonne National Laboratory, USA), Prof. Jeff Dahn (Dalhousie University, Canada) and Prof. Martin Winter (Münster Universität/MEET, Germany), who are established authorities in battery and materials research.

I owe much to the late Prof. John O’M. Bockris, whose colloquial style in teaching a sophisticated mathematical topic had a significant influence on me. Between 1995 and 1997, when he was working on the second edition of the monumental textbook Modern Electrochemistry, I was lucky enough to assist him as a contributor of exercise problems for that book. This unique experience benefited me considerably as a student, a researcher and a scientific writer.

Significant influences also came from my PhD advisor, the late Prof. Austen Angell, who not only shaped my career but also continued to help me long after I graduated from his group. He showed me what a scientist should be like.

Despite the invitation from the editors in mid-2015, I had been procrastinating until my friend Prof. Lidan Xing (South China Normal University) encouraged me to start this ambitious project in the spring of 2020. My colleague and friend Dr Janet Ho (US Army Research Laboratory) provided much inspiration and material support during the writing. She is also credited for taking the photograph of me while finishing this book.

Professors Ping Liu (University of California San Diego), Shirley Meng (University of California San Diego), Chunsheng Wang (University of Maryland College Park) and Lidan Xing (South China Normal University) provided valuable suggestions from a teaching perspective.

Dr Lin Ma (ARL/University of Maryland) helped me to access many literature sources, Dr Jenel Vatamanu (US Army Research Laboratory) provided assistance in simulating how charges distribute on an inert electrode surface and Dr Oleg Borodin (US Army Research Laboratory) engaged in fruitful discussions about many fundamental topics related to ion solvation, ion transport and ion assembly on interfaces, and helped me to understand how computer simulation works. My son Michael helped with some of the mathematics and illustrations.

Professors Nitash Balsara (Lawrence Berkeley National Laboratory) and Paul Albertus (University of Maryland) provided invaluable help with the understanding of the Newman formalism of ion transport and discussions on Newman’s concentrated solution theory. The comments and views on the limitations of Newman’s theory, however, only reflect my personal perspective.

Many respected colleagues assisted me with either scientific literature, images or discussions on specific topics during my writing. They are Prof. Martin Bazant (Massachusetts Institute of Technology), Dr Ratnakumar Bugga (Jet Propulsion Laboratory, NASA), Prof. Jeff Dahn (Dalhousie University), Dr Lei Cheng (Argonne National Laboratory), Dr Michael S. Ding (US Army Research Laboratory), Dr Tao Gao (University of Utah), Dr Rongzhong Jiang (US Army Research Laboratory), Prof. Bernhard Roling (Philipps-Universität Marburg), Prof. Monika Schönhoff (Universität Münster), Dr Marshall Smart (Jet Propulsion Laboratory), Prof. Yicheng Song (Shanghai University), Dr Karen Thomas-Alyea (Verdox Inc.), Prof. Chunsheng Wang (University of Maryland College Park), Prof. Masayoshi Watanabe (Yokohama National University), Prof. Martin Winter (Westfälische Wilhelms-Universität Münster/MEET), Dr Wu Xu (Pacific Northwest National Laboratory), Dr Zhou Yu (Argonne National Laboratory), Dr Jason Zhang (Pacific Northwest National Laboratory) and Prof. Shengshui Zhang (US Army Research Laboratory).

I am grateful to the Joint Center of Energy Storage Research (JCESR), an energy hub funded by the Department of Energy Office of Science and led by Dr George Crabtree and Dr Venkat Srinivasan of Argonne National Laboratory. The JCESR not only supported the research activities in my group on multivalent cation electrolytes, but more importantly granted me the opportunity to work alongside so many brilliant scientists from whom I have learned so much.

Although this book was written outside my official working hours, I want to thank the US Army and DEVCOM Army Research Laboratory for continually supporting my scientific exploration. My first-line supervisors Dr Cynthia Lundgren and then Dr Kyle Grew did their best to create the optimal environment to cultivate the culture of encouraging scientific exploration.

I want to thank the RSC editorial staff Ms Katie Morrey for her assistance in planning and contracting, and her patience with me during 2 years, and Ms Amina Headley for her proofreading. Their enormous efforts made this book possible. Thanks also to the RSC Production team, Dr Helen Potter, Mr Connor Sheppard and Dr Caroline Knapp for their efforts during the production process.

Finally, I want to thank my wife, whose understanding and tolerance for my long hours in the office and in my study allowed me to take on and finish this ambitious project.

Kang Xu

Potomac, Maryland, USA