Inorganic Battery Materials E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Serie: EIC Books
• Sprache: Englisch

Seitenzahl: 1190

Veröffentlichungsjahr: 2019

Beschreibung

A guide to the fundamental chemistry and recent advances of battery materials In one comprehensive volume, Inorganic Battery Materials explores the basic chemistry principles, recent advances, and the challenges and opportunities of the current and emerging technologies of battery materials. With contributions from an international panel of experts, this authoritative resource contains information on the fundamental features of battery materials, discussions on material synthesis, structural characterizations and electrochemical reactions. The book explores a wide range of topics including the state-of-the-art lithium ion battery chemistry to more energy-aggressive chemistries involving lithium metal. The authors also include a review of sulfur and oxygen, aqueous battery chemistry, redox flow battery chemistry, solid state battery chemistry and environmentally beneficial carbon dioxide battery chemistry. In the context of renewable energy utilization and transportation electrification, battery technologies have been under more extensive and intensive development than ever. This important book: * Provides an understanding of the chemistry of a battery technology * Explores battery technology's potential as well as the obstacles that hamper the potential from being realized * Highlights new applications and points out the potential growth areas that can serve as inspirations for future research * Includes an understanding of the chemistry of battery materials and how they store and convert energy Written for students and academics in the fields of energy materials, electrochemistry, solid state chemistry, inorganic materials chemistry and materials science, Inorganic Battery Materials focuses on the inorganic chemistry of battery materials associated with both current and future battery technologies to provide a unique reference in the field. About EIBC Books The Encyclopedia of Inorganic and Bioinorganic Chemistry (EIBC) was created as an online reference in 2012 by merging the Encyclopedia of Inorganic Chemistry and the Handbook of Metalloproteins. The resulting combination proves to be the defining reference work in the field of inorganic and bioinorganic chemistry, and a lot of chemistry libraries around the world have access to the online version. Many readers, however, prefer to have more concise thematic volumes in print, targeted to their specific area of interest. This feedback from EIBC readers has encouraged the Editors to plan a series of EIBC Books [formerly called EIC Books], focusing on topics of current interest. EIBC Books will appear on a regular basis, will be edited by the EIBC Editors and specialist Guest Editors, and will feature articles from leading scholars in their fields. EIBC Books aim to provide both the starting research student and the confirmed research worker with a critical distillation of the leading concepts in inorganic and bioinorganic chemistry, and provide a structured entry into the fields covered.

Leseprobe

EIBC Books

Application of Physical Methods to Inorganic and Bioinorganic Chemistry

Edited by Robert A. Scott and Charles M. Lukehart

ISBN 978-0-470-03217-6

Nanomaterials: Inorganic and Bioinorganic Perspectives

Edited by Charles M. Lukehart and Robert A. Scott

ISBN 978-0-470-51644-7

Computational Inorganic and Bioinorganic Chemistry

Edited by Edward I. Solomon, R. Bruce King and Robert A. Scott

ISBN 978-0-470-69997-3

Radionuclides in the Environment

Edited by David A. Atwood

ISBN 978-0-470-71434-8

Energy Production and Storage: Inorganic Chemical Strategies for a Warming World

Edited by Robert H. Crabtree

ISBN 978-0-470-74986-9

The Rare Earth Elements: Fundamentals and Applications

Edited by David A. Atwood

ISBN 978-1-119-95097-4

Metals in Cells

Edited by Valeria Culotta and Robert A. Scott

ISBN 978-1-119-95323-4

Metal-Organic Framework Materials

Edited by Leonard R. MacGillivray and Charles M. Lukehart

ISBN 978-1-119-95289-3

The Lightest Metals: Science and Technology from Lithium to Calcium

Edited by Timothy P. Hanusa

ISBN 978-1-118-70328-1

Sustainable Inorganic Chemistry

Edited by David A. Atwood

ISBN 978-1-118-70342-7

Metalloprotein Active Site Assembly

Edited by Michael K. Johnson and Robert A. Scott

ISBN 978-1-11915983-4

The Heaviest Metals: Science and Technology of the Actinides and Beyond

Edited by William J. Evans and Timothy P. Hanusa

ISBN 978-1-11930409-8

Inorganic Battery Materials

Edited by Hailiang Wang and Boniface P.T. Fokwa

ISBN 978-1-11943199-2

Encyclopedia of Inorganic and Bioinorganic Chemistry

The Encyclopedia of Inorganic and Bioinorganic Chemistry (EIBC) was created as an online reference in 2012 by merging the Encyclopedia of Inorganic Chemistry and the Handbook of Metalloproteins. The resulting combination proves to be the defining reference work in the field of inorganic and bioinorganic chemistry. The online edition is regularly updated and expanded. For information see:

www.wileyonlinelibrary.com/ref/eibc

Inorganic Battery Materials

Editors

Hailiang Wang

Yale University, New Haven, CT, USA

Boniface P.T. Fokwa

University of California, Riverside, CA, USA

Copyright

This edition first published 2020

© 2020 John Wiley & Sons, Ltd

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Library of Congress Cataloging‐in‐Publication Data has been applied for.

978‐1‐119‐43199‐2 (hardback)

Cover Design: Wiley

Cover Images: © Hailiang Wang, © 2019 International Union of Pure and Applied Chemistry

Encyclopedia of Inorganic and Bioinorganic Chemistry

Editorial Board

Editor‐in‐Chief

Robert A. Scott

University of Georgia, Athens, GA, USA

Section Editors

Boniface P.T. Fokwa

University of California, Riverside, CA, USA

Timothy P. Hanusa

Vanderbilt University, Nashville, TN, USA

Jason B. Love

University of Edinburgh, Edinburgh, UK

Rebecca L. Melen

Cardiff University, Cardiff, UK

Albrecht Messerschmidt

Max‐Planck‐Institute für Biochemie, Martinsried, Germany

Robert A. Scott

University of Georgia, Athens, GA, USA

Associate Editors

Yvain Nicolet

Institut de Biologie Structurale, Grenoble, France

Tim Storr

Simon Fraser University, Burnaby, BC, Canada

Holger Helten

RWTH Aachen University, Aachen, Germany

Editor‐in‐Chief Emeritus & Senior Advisors

Robert H. Crabtree

Yale University, New Haven, CT, USA

R. Bruce King

University of Georgia, Athens, GA, USA

International Advisory Board

David A. Atwood

University of Kentucky, KY, USA

Michael Bruce

Adelaide, Australia

Tristram Chivers

Calgary, Canada

Valeria Culotta

MD, USA

Mirek Cygler

Saskatchewan, Canada

Marcetta Darensbourg

TX, USA

Michel Ephritikhine

Gif-sur-Yvette, France

Robert Huber

Martinsried, Germany

Susumu Kitagawa

Kyoto, Japan

Charles M. Lukehart

Vanderbilt University, Nashville, TN, USA

Leonard R. MacGillivray

IA, USA

Thomas Poulos

CA, USA

David Schubert

CO, USA

Edward I. Solomon

CA, USA

Katherine Thompson

Vancouver, Canada

T. Don Tilley

CA, USA

Karl E. Wieghardt

Mülheim an der Ruhr, Germany

Vivian Yam

Hong Kong

Contributors

Hye Ryung Byon

Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea

Lithium Oxygen Battery

Shaowei Chen

South China University of Technology, Guangzhou, China

University of California, Santa Cruz, CA, USA

Structural Engineering of Cathode Materials for Lithium–Sulfur Batteries

Jaephil Cho

Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea

How to Maximize the Potential of Zn–Air Battery: Toward Acceptable Rechargeable Technology with or without Electricity

Francesco Ciucci

Hong Kong University of Science and Technology, Hong Kong, China

Modeling Solid State Batteries

Camden DeBruler

Utah State University, Logan, UT, USA

Redox‐Active Inorganic Materials for Redox Flow Batteries

Kaoru Dokko

Yokohama National University, Yokohama, Japan

Lithium Oxygen Battery

Elizabeth H. Driscoll

University of Birmingham, Birmingham, UK

Na‐Ion Batteries: Positive Electrode Materials

Laura L. Driscoll

University of Birmingham, Birmingham, UK

Na‐Ion Batteries: Positive Electrode Materials

Bin Fan

South China University of Technology, Guangzhou, China

Structural Engineering of Cathode Materials for Lithium–Sulfur Batteries

Bo Hu

Utah State University, Logan, UT, USA

Redox‐Active Inorganic Materials for Redox Flow Batteries

Liangbing Hu

University of Maryland, College Park, MD, USA

Solid‐State Electrolyte

Maowei Hu

Utah State University, Logan, UT, USA

Redox‐Active Inorganic Materials for Redox Flow Batteries

Sooyeon Hwang

Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY, USA

TEM Studies on Electrode Materials for Secondary Ion Batteries

Jang‐Soo Lee

Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea

How to Maximize the Potential of Zn–Air Battery: Toward Acceptable Rechargeable Technology with or without Electricity

Feng Li

University of Idaho, Moscow, ID, USA

S Electrode Materials

Ligui Li

South China University of Technology, Guangzhou, China

Structural Engineering of Cathode Materials for Lithium–Sulfur Batteries

Siyuan Li

Zhejiang University, Hangzhou, China

Lithium Metal Anode

Xiaolin Li

Pacific Northwest National Laboratory, Richland, WA, USA

Silicon‐Based Anodes for Advanced Lithium‐Ion Batteries

Feng Lin

Virginia Tech, Blacksburg, VA, USA

Surface Chemistry of Alkali‐Ion Battery Cathode Materials

T. Leo Liu

Utah State University, Logan, UT, USA

Redox‐Active Inorganic Materials for Redox Flow Batteries

Yingying Lu

Zhejiang University, Hangzhou, China

Lithium Metal Anode

Ziheng Lu

Hong Kong University of Science and Technology, Hong Kong, China

Modeling Solid State Batteries

Jian Luo

Utah State University, Logan, UT, USA

Redox‐Active Inorganic Materials for Redox Flow Batteries

Wei Luo

Tongji University, Shanghai, China

Solid‐State Electrolyte

Laura C. Merrill

University of Notre Dame, Notre Dame, IN, USA

Multivalent Metallic Anodes for Rechargeable Batteries

Joohyuk Park

Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea

How to Maximize the Potential of Zn–Air Battery: Toward Acceptable Rechargeable Technology with or without Electricity

Jelena Popovic

Max Planck Institute for Solid State Research, Stuttgart, Germany

Chemistry of Soft Matter Battery Electrolytes

Muhammad M. Rahman

Virginia Tech, Blacksburg, VA, USA

Surface Chemistry of Alkali‐Ion Battery Cathode Materials

Philip N. Ross

Lawrence Berkeley National Laboratory, Berkeley, CA, USA

Solid Electrolyte Interphase in Lithium‐Based Batteries

Jennifer L. Schaefer

University of Notre Dame, Notre Dame, IN, USA

Multivalent Metallic Anodes for Rechargeable Batteries

Divya Sehrawat

University of New South Wales (UNSW Sydney), Sydney, Australia

Solid State and Materials Chemistry for Sodium‐Ion Batteries

Reza Shahbazian‐Yassar

University of Illinois at Chicago, Chicago, IL, USA

Application of In Situ Electrochemical‐Cell Transmission Electron Microscopy for the Study of Rechargeable Batteries

Neeraj Sharma

University of New South Wales (UNSW Sydney), Sydney, Australia

Solid State and Materials Chemistry for Sodium‐Ion Batteries

Feifei Shi

Stanford University, Stanford, CA, USA

Solid Electrolyte Interphase in Lithium‐Based Batteries

Peter R. Slater

University of Birmingham, Birmingham, UK

Na‐Ion Batteries: Positive Electrode Materials

Junhua Song

Pacific Northwest National Laboratory, Richland, WA, USA

Silicon‐Based Anodes for Advanced Lithium‐Ion Batteries

Jennifer H. Stansby

University of New South Wales (UNSW Sydney), Sydney, Australia;

Australia Nuclear Science and Technology Organisation, Sydney, Australia

Solid State and Materials Chemistry for Sodium‐Ion Batteries

Dong Su

Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY, USA

TEM Studies on Electrode Materials for Secondary Ion Batteries

Xiaowei Teng

University of New Hampshire, Durham, NH, USA

Electrode and Electrolyte Interaction in Aqueous Electrochemical Energy Storage

Morgan L. Thomas

Yokohama National University, Yokohama, Japan

Lithium Oxygen Battery

Ting Hei Wan

Hong Kong University of Science and Technology, Hong Kong, China

Modeling Solid State Batteries

Nan Wang

South China University of Technology, Guangzhou, China

Structural Engineering of Cathode Materials for Lithium–Sulfur Batteries

Masayoshi Watanabe

Yokohama National University, Yokohama, Japan

Lithium Oxygen Battery

Raymond A. Wong

Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea

Lithium Oxygen Battery

Wenda Wu

Utah State University, Logan, UT, USA

Redox‐Active Inorganic Materials for Redox Flow Batteries

Zhaojun Xie

Nankai University, Tianjin, China

Li–CO

2

Batteries

Jixiang Yang

Zhejiang University, Hangzhou, China

Lithium Metal Anode

Wanli Yang

Advanced Light Source, E O Lawrence Berkeley National Laboratory, Berkeley, CA, USA

Synchrotron‐Based Soft X‐Ray Spectroscopy for Battery Material Studies

Wentao Yao

Michigan Technological University, Houghton, MI, USA

Application of In Situ Electrochemical‐Cell Transmission Electron Microscopy for the Study of Rechargeable Batteries

Chuang Yu

Delft University of Technology, Delft, The Netherlands

Solid‐State Electrolyte

Jingping Yu

South China University of Technology, Guangzhou, China

Structural Engineering of Cathode Materials for Lithium–Sulfur Batteries

Shuaibo Zeng

South China University of Technology, Guangzhou, China

Structural Engineering of Cathode Materials for Lithium–Sulfur Batteries

Ji‐Guang Zhang

Pacific Northwest National Laboratory, Richland, WA, USA

Silicon‐Based Anodes for Advanced Lithium‐Ion Batteries

Jun Zhao

South China University of Technology, Guangzhou, China

Structural Engineering of Cathode Materials for Lithium–Sulfur Batteries

Zhen Zhou

Nankai University, Tianjin, China

Li–CO

2

Batteries

Series Preface

The success of the Encyclopedia of Inorganic Chemistry (EIC), pioneered by Bruce King, the founding Editor in Chief, led to the 2012 integration of articles from the Handbook of Metalloproteins to create the newly launched Encyclopedia of Inorganic and Bioinorganic Chemistry (EIBC). This has been accompanied by a significant expansion of our Editorial Advisory Board with international representation in all areas of inorganic chemistry. It was under Bruce's successor, Bob Crabtree, that it was recognized that not everyone would necessarily need access to the full extent of EIBC. All EIBC articles are online and are searchable, but we still recognized value in more concise thematic volumes targeted to a specific area of interest. This idea encouraged us to produce a series of EIC (now EIBC) Books, focusing on topics of current interest. These will continue to appear on an approximately annual basis and will feature the leading scholars in their fields, often being guest coedited by one of these leaders. Like the Encyclopedia, we hope that EIBC Books continue to provide both the starting research student and the confirmed research worker a critical distillation of the leading concepts and provide a structured entry into the fields covered.

The EIBC Books are referred to as spin‐on books, recognizing that all the articles in these thematic volumes are destined to become part of the online content of EIBC, usually forming a new category of articles in the EIBC topical structure. We find that this provides multiple routes to find the latest summaries of current research.

I fully recognize that this latest transformation of EIBC is built on the efforts of my predecessors, Bruce King and Bob Crabtree, my fellow editors, as well as the Wiley personnel, and, most particularly, the numerous authors of EIBC articles. It is the dedication and commitment of all these people that are responsible for the creation and production of this series and the “parent” EIBC.

Robert A. Scott

University of Georgia

Department of Chemistry

August 2019

Volume Preface

Rechargeable batteries, converting between chemical energy and electrical energy, are not only a currently dominant power source for portable electronics, cordless tools, electrochemical energy storage, and electric vehicles but are also closely related to the future of humanity's efficient and balanced energy consumption. The exponential growth of energy demand in our modern society has made rechargeable batteries one of the essential ingredients to satisfy our quest for more and more energy. Equally important is the fact that rechargeable batteries are playing a crucial role in climate change by helping to advance green energy technologies such as solar and wind. Consequently, it is urgent to build better batteries by making them more energy intensive, faster, more durable, safer, and cheaper. While incremental improvements of available batteries are being successfully pursued in the industry by design or architecture modifications, exploring and understanding new chemistries and materials will be necessary to address these challenges. This has stimulated extensive research on designing, synthesizing, and characterizing inorganic materials (broadly defined) for many battery technologies.

Inorganic Battery Materials, a newly added volume to The Encyclopedia of Inorganic and Bioinorganic Chemistry, is the product of excellent contributions from prominent experts from Asia, Australia, Europe, and North America. Selective overviews and critical perspectives are provided for battery technologies from the state‐of‐the‐art lithium ion battery chemistry to more energy‐aggressive chemistries involving lithium metal, sulfur, and oxygen; abundant metals including sodium, magnesium, calcium, and aluminum; aqueous battery chemistry; redox flow battery chemistry; solid state battery chemistry; and environmentally beneficial carbon dioxide battery chemistry. In addition to battery materials, extensive discussion is also dedicated to the development and employment of advanced structural characterization techniques, including synchrotron‐based X‐ray spectroscopy, vibrational spectroscopy, and transmission electron microscopy, to understand the structure–property correlations and working/failing mechanisms.

We would like to thank the editorial staff at Wiley for their expert guidance and assistance throughout the entire project. It could not have been completed without their steadfast help.

Hailiang Wang

Yale University,

New Haven, CT, USA

Boniface P.T. Fokwa

University of California,

Riverside, CA, USA

August 2019

Part 1Chemistry of Li‐Ion Battery Materials

Silicon‐Based Anodes for Advanced Lithium‐Ion Batteries

Junhua Song, Xiaolin Li and Ji‐Guang Zhang

Pacific Northwest National Laboratory, Richland, WA, USA

1 Introduction

2 Nanostructure Design

3 Binder Effect

4 Electrolyte Optimization and Interphase Engineering

5 Practical Perspectives of S‐Based Anodes in Full Cells

6 Challenges and Outlook

7 Abbreviations and Acronyms

8 References

1 Introduction

Since the commercial introduction of lithium‐ion batteries (LIBs) in 1990s by Sony Corporation, the quest for high energy density rechargeable batteries has become burgeoningly active.(1–3) In the past decades, the energy density has taken a threefold increment from the first‐generation LIB (80 Wh kg−1) to today's 240 Wh kg−1.(4) The advancement of battery performance has been driven by several technical breakthroughs, such as the discovery of layered transition‐metal oxide cathode material, LiCoO2, in the 1980s by John Goodenough,(5,6) and using carbonaceous anode materials as Li‐ion hosts. With the continuous efforts on the optimization of materials processing, improvements on the inactive components (including electrolyte, separator and binder, conductive additive, and current collector) and engineering progress in manufacturing, the ceiling of Li‐ion's energy density is approaching its theoretical limits with the general concept of insertion anode and cathode pair. While technological achievements play a key role in boosting the LIBs' performance, the consumer demands, growing consciousness of sustainability, and pursue of cost‐effectiveness in production have also driven the research for further improvements of the already powerful Li‐ion chemistry. Nowadays, the surging number of the electrical vehicles (EVs) is gradually taking the dominating role in consuming high energy density LIBs, while their demands were marginally low in 2010 compared to those used in computers, consumer electronics, and cameras, also known as the 3C market.(7,8) However, the growing trend of electrifying the transportation systems requires a leap in the LIB technology to significantly extend the driving distance of EVs so that consumers can be freed from the range anxiety. Similar to the technical breakthroughs before the birth of Li‐ion chemistry, finding a high‐performance anode material holds a great promise meeting the increasing demand on LIBs' energy density, reliability, and low cost. The state‐of‐the‐art graphite anode has been the top choice in today's LIBs with its low charge/discharge potential, moderate capacity of 372 mAh g−1, and low manufacturing cost (Table 1). Among all the alternative anode materials, silicon (Si) is considered the most promising candidate for the next‐generation high‐energy LIBs for several reasons: (i) Si has a theoretical specific capacity of 4200 mAh g−1 and volumetric capacity of 9786 mAh cm−3 upon full lithiation (Li4.4Si), which are ∼10 times larger than graphite(9); (ii) the lithiation/delithiation potential averages at ∼0.4 V versus Li, which ensures a relatively high operation voltage in full cell configuration as well as prevents safety concerns caused by lithium plating at low anode voltage(10); (iii) the potentially low toxicity, low cost, environmental friendliness, and natural abundance of Si render it the most suitable substitution to graphite anode. Nevertheless, the promises never come without a challenge. The efforts to make Si anodes practically adopted in LIBs have gone through a long research development process that is not completed yet.

Tab. 1 Comparison of the state‐of‐the‐art anode materials for LIBs

Anode

Graphite

Silicon

LTO

Lithium

Gravimetric capacity (mAh g

−1

)

372

4200

175

3862

Volumetric capacity (mAh cm

−3

)

837

9786

613

2047

Volume change (%)

12

420

1

∞

Average potential vs Li (V)

0.05

0.4

1.6

0

Cost

Low

Low

Medium

High

Early trials in the 1970s using Li–Si alloy in electrochemical cells operated at elevated temperature >400 °C and suffered poor reversibility at room temperature owing to the large volume change.(11,12) Since then, tackling the structural damage and improving its room temperature performance have been the research focus of using Si‐based anode in LIBs. In the early 1990s, Dahn et al. examined the SixOyCz glass composite derived from Si‐containing polymers. By tuning the Si content in the final product, his group was able to achieve a reversible capacity of 900 mAh g−1 at room temperature in half‐cell configuration.(13) Their results marked the possibility of replacing graphite with high‐capacity Si as anode in LIBs. As materials science research entered the nano era, it also encouraged the exploration of using nano‐sized Si as anode materials in the late 1990s. To fabricate nanoscale Si with controllable size, Si film was made with chemical vapor deposition (CVD) and able to achieve a capacity as high as 1000 mAh g−1, despite the cyclability being quite limited due to the structural breakdown associated with huge volume change of the thin‐film electrode.(14) Later at the beginning of the twenty‐first century, several major material breakthroughs have taken place in the Si anode research. One is to construct composite Si alloys (FeSi2, NiSi2, and BaSi2), which effectively extends the cyclic stability to 50 cycles.(15–17) The new compositing methods have also enabled nano Si particles to stably operate over 100 cycles.(18) More encouragingly, modification made on current collectors rendered the Si thin film (50 nm in thickness) anode cycle over 1000 cycles with reversible capacities as high as ∼2000 mAh g−1. Up to this point, the general challenges in applying Si anode in LIBs are gradually self‐revealed.

Tab. 2 Summary of the challenges and solutions to the Si anode in LIBs

Challenge

Volume expansion

Particle pulverization

Electrode delamination

SEI formation

Solution

Nanostructured materials with predesigned void space

Reducing the primary particle size

Binder optimization

Artificial SEI

Surface coating

Reducing particle volume expansion

Electrolyte optimization

Nanostructure design

Reduce surface area

Unlike the small volume change (∼10%) during lithium uptake in graphite, Si expands up to 420% upon full lithiation.(19) The drastic volume swing stresses the integrity of the Si materials and brings destructive outcomes to the battery performance. The major problems associated with the Si anode during cycling are the following: (i) on the material level, the cracking and pulverization of Si particle sacrifice the electrical contact between particles and expose reactive new surface that consumes electrolyte in the following cycles; (ii) on the electrode level, delamination and electrical disconnections occur under huge interfacial stress generated; and (iii) on the cell level, the electrically segregated Si particles decrease the capacity utilization, facilitating thick insulating interphase build‐up and hence leading to the rapid capacity fade (Figure 1). All of these issues accelerate electrolyte consumption rate, introduce safety hazard, and negatively affect the cell operation. Despite as challenging as it is, tremendous efforts have been made to improve the Si anode performance by designing beneficial nanostructures, improving interfacial properties, modifying inactive components, and optimizing testing conditions. A short summary of the challenges of Si materials and the corresponding solutions is listed in Table 2. Assisted by the knowledge gained in manipulating atoms and molecules at nanoscale, the Si anode research has entered an era with explosive progress on cell performance. To mitigate volume expansion, nanostructured materials with intentionally designed void space were designed and showed promising performance. The major consequence of volume expansion, that is, particle pulverization, was effectively tackled by the applying small size nano Si and constructing nanostructure with intentionally left void space. These nano strategies will be introduced and detailed in the Section 2 of this chapter. Leveraging the reduced particle swelling, the electrode‐level engineering against swelling was achieved by selecting a right binder material, which was designed to tightly hold the active particles together under mechanical stress and, in some cases, to improve the conductivity of the particle. The progress on new genre of binder materials and their positive influence on electrode stability are covered in Section 3. Another negative outcome of Si volume expansion is the unstable solid‐electrolyte‐interphase (SEI). The cracked particle exposes new surface and initiates the growth of thick interfacial layer, which are detrimental to the cell impedance and electrolyte sustainability. The most effective way of addressing the interphase issue is through the electrolyte optimization and surface engineering. An appropriate choice of electrolyte additive is able to preferentially build a relatively stable SEI that can mitigate the electrolyte consumption during the long‐term cell operation. The merits of electrolyte and interphase engineering beneficial for Si materials are highlighted in Section 3. In the end, the remaining challenges and practical aspects of Si‐based anode materials are touched with the special focus on the full cell configuration. We hope the short walkthrough of the Si technology will help the readers have a grasp of the efforts made in improving the performance of electrochemical rechargeable batteries and appreciate the outcomes of the fundamental research brought to the development of practical Si‐based LIBs.

Fig. 1 Schematic illustration of the silicon anode degradation mechanism.(20)

[Reproduced with permission from J. W. Choi, D. Aurbach, Nat. Rev. Mater. 2016, 1. © Springer Nature Limited, 2016]

Fig. 2 Representative Si nanostructures. (a) Si nanoparticles at full lithiation state.(25) (b) Hollow Si nanospheres.(26) [Reprinted with permission from Y. Yao, M. T. McDowell, I. Ryu, H. Wu, N. A. Liu, L. B. Hu, W. D. Nix, Y. Cui, Nano Lett. 2011, 11, 2949–2954. © American Chemical Society 2011]; (c) Schematic illustration of Si nanowire.(27) [Reproduced with permission from C. K. Chan, H. L. Peng, G. Liu, K. McIlwrath, X. F. Zhang, R. A. Huggins, Y. Cui, Nat. Nanotechnol. 2008, 3, 31–35. © Springer Nature Limited, 2016]; (d) Hollow Si nanowire. Schematic illustration of Si nanowire.(28) [Reproduced with permission from H. Wu, G. Chan, J. W. Choi, I. Ryu, Y. Yao, M. T. McDowell, S. W. Lee, A. Jackson, Y. Yang, L. B. Hu, Y. Cui, Nat. Nanotechnol. 2012, 7, 309–314. © Springer Nature Limited, 2012]; (e) Graphical representation of pomegranate Si consisting of nano yolk‐shell Si@C particles.(29) [Reproduced with permission from N. Liu, Z. D. Lu, J. Zhao, M. T. McDowell, H. W. Lee, W. T. Zhao, Y. Cui, Nat. Nanotechnol. 2014, 9, 187–192. © Springer Nature Limited, 2014]; (f) Images of mesoporous silicon sponge at different scale.(30)

[Reproduced with permission from X. L. Li, M. Gu, S. Y. Hu, R. Kennard, P. F. Yan, X. L. Chen, C. M. Wang, M. J. Sailor, J. G. Zhang, J. Liu, Nat. Commun. 2014, 5, 4105. © Springer Nature Limited, 2014]

2 Nanostructure Design

Si anode stands out as the top candidate to replace graphite with its high specific capacity by forming Li4.4Si alloy. However, this large capacity is also accompanied by drastic volume expansion up to 420%. The change in material dimension puts serious threats to the materials integrity and interphase stability, which are supposed to be stable and intact during cell operation. In addition, the cracked Si particles also leave them out of reach from the conductive components in the electrode, and hence their capacitive contribution is lost. Nanoscience and technology bring hope for tackling the Si volume expansion issue, since downsizing the material dimension usually comes with unique mechanical, physiochemical properties and structural flexibility that are absent in the bulk counterpart.(21–23) Among the different nanostructures, nano Si particles with small diameters, Si nanowires (NWs), hollow Si nanospheres/tubes, yolk‐shell structure, and porous silicon are the most promising designs in addressing the consequences associated with Si volume expansion.

As documented by early Si research, crystalline Si underwent a unique two‐phase lithiation process, where the large tensile stress was built up to initiate the surface cracks. It was first reported by Liu et al.,(24) a strong size‐dependent fracture of Si nanoparticle was observed in real time with in situ transmission electron microscopy (TEM). For particle size smaller than 150 nm, Si is free from cracking or facture upon full lithiation. This is due to an insufficient amount of strain energy release in driving crack propagation in Si particles smaller than the critical size. A more detailed study on the lithiation kinetics revealed that the changing mechanical stress at the reaction front altered the total driving force for lithiation reaction and hence results in slow lithiation process and structural breakdown (Figure 2a).(25) In fact, a critical size effect exits even in particles that are smaller than 50 nm. It was found that the 20 nm Si particles showed much improved cyclic stability than 5 and 10 nm.(31) Since the mechanical stress during lithiation/delithiation is the initiator of cracking, hollow structure with thin Si wall and void core was fabricated to solve the problem. Yao et al.(26) used 350‐nm SiO2 particles as hard templates to fabricate interconnected Si hollow spheres (Figure 2b). It was simulated that the maximum tensile stress of solid sphere was about five times higher than that in hollow sphere at an equal volume of Si and hence make the hollow Si less susceptible to fracture. Owing to the structural advantages, the hollow spheres can deliver a capacity of 2725 mAh g−1 at 0.1 C (1 C equals the current required to discharge the battery in 1 h) and retain over half of its capacity after 700 cycles at 0.5 C. The thin Si wall in the porous structure also gave the material a high rate capability, featured with 73% capacity retention at 5 C compared to 0.2 C (2417 mAh g−1).

Besides downsizing the particle size and creating hollow structure, Si NWs also showed excellent properties in circumventing the particle fracture issue. Chan et al.(27) have demonstrated that with Si NWs grown directly on stainless steel current collectors. The unique wire structure showed high charge/discharge capacity close to theoretical value and retained most of the initial capacity with little fading during cycling. Although structural morphology and dimension changed after lithium uptake, the facile strain relaxation of Si NWs allowed it to be intact and undamaged during cycling (Figure 2c). Similar to the zero‐dimensional hollow Si particles, the same concept was adopted in one‐dimensional particles and demonstrated good electrochemical performance. Wu et al.(28) showed an anode material using silicon nanotube wrapped by an ion‐permeable silicon oxide shell and were able cycle it for 6000 times in half‐cell configuration with over 85% capacity retention. The double‐walled tubular structure provided stable SEI layer, sufficiently accommodated the Si volume expansion, and exhibited eight times larger reversible capacity in large current test compared to conventional graphite anodes (Figure 2d).

Another effort to confront negative effects of Si volume expansion is to intentionally create void space to host the lithiated and/or cracked Si, that is, the yolk‐shell structure. The signature of yolk‐shell structure is the additional internal void space between the core particles and the outer shells that is purposely left during synthesis. The predesigned void space can accommodate Si volume expansion, which means the volume of yolk‐shell particle as a whole stays the same during cycling. The internal room left is rather important since the integrity of the electrode depends on the dimensional stability of the active material. As volume changes are confined within the “shell”, the safety issues related to the electrode/cell swelling can be largely evaded. The existence of the outer shell and void space also brings other advantages compare to solid Si: (i) inwardwise, the outer shell serves as a protective layer to prevent cracked Si “yolk” from losing electrical contact by scattering around upon volume change; (ii) outwardwise, the layer of carbon shell can help establish a robust and stable SEI layer, which would otherwise continuously grow on the broken Si surface during cycling; (iii) the conductive nature of the carbon also lifts the capacity utilization of the insulating Si, even if it is disintegrated inside the shell. Yi Cui 's group designed a yolk shell structure using nano Si particles encapsulated by a thin conformal and self‐supporting carbon shell.(32) This structure demonstrated excellent capacity of 2833 mAh g−1 at 400 mA g−1 and showed impressive 74% capacity retention, after 1000 cycles with an average 99.84% Coulombic efficiency.

In the follow‐up work, his group further fabricated a pomegranate structure consisting of myriads of nano yolk‐shell Si particles.(29) This structure not only alleviated the mechanical stress induced by volume expansion of nano Si, but also successfully increased the tap density and volumetric capacity that are hard to achieve with nanomaterials (Figure 2e). The successful combination of the merits of both yolk‐shell structure and hierarchical microsphere design showed excellent cyclic stability with 97% capacity retention after 1000 cycles with high Coulombic efficiency (99.87%) and volumetric capacity of 1270 mAh cm−3. Conventionally, yolk shell structure has to go through multistep synthetic route, including SiO2 coating, carbon coating, and acid etching. Although the structure is quite effective in lifting the Si performance, the chemical synthesis is usually time‐consuming and hard to scale up in practical scenario. To address this problem, Li et al.(33) proposed a low‐cost strategy by oxidizing the nano Si in air to create an SiO2 surface layer followed by carbon coating and hydrofluoric acid etching of the SiO2 layer. By controlling the oxidation and etching time, the void space of the structure can be easily tuned to buffer the Si expansion.

All the destructive outcomes of switching to high‐capacity Si anode come from the changing volume of Si during cycling. Thus, preleft void space is important to the stability of active materials as well as the integrity of the electrode. Besides the yolk‐shell structure, porous silicon also takes advantage of having predesigned pore volume to absorb the dimension change associated with lithiated Si. Although the benefits of using nano Si have brought hope of significantly boosting the energy density of LIBs, their unique properties also come with unavoidable drawbacks. Owing to the high surface area and complex synthesis conditions, anode with nano Si usually suffers from low tap/calendaring density, low Coulombic efficiency, and high cost. To address these issues, but at the same time preserve the merits of nano Si, are considered the paramount tasks in silicon structure design. Bulk porous Si seems to be the optimum solution, which has been found possessing the structural advantages lend from nanoporous materials without compromising the easy manufacturing ability and low cost of bulk Si. One exemplary design was the mesoporous silicon sponge structure by the research team at Pacific Northwestern National Laboratory (PNNL).(30) Using an electrochemical etching method, large silicon particles (20 µm) with rich mesopores demonstrated excellent performance as Li‐ion anode. (Figure 2f) The micron‐size silicon particle consisted of large pores up to 50 and 10 nm thin Si wall. In situ observation of the lithiation/delithiation process revealed that the volume change of the porous Si was merely ∼30% compared to the 360% in the conventional Si. More importantly, there was no particle pulverization observed even after a thousand continuous cycles. This unique structure delivered an impressive capacity retention of 92% at high area‐specific capacity of ∼1.5 mAh cm−2 over 300 cycles. It was an encouraging study that demonstrated the successful marriage between porous nanostructure design and manufacturing friendly bulk Si materials at practical testing conditions. While the antipulverization and volume accommodation structures are highly desirable features, simple and scalable syntheses are hard to meet using Si anode at nanoscale. On the basis of such concern, Yi et al