Title: Material and Structural Design of Novel Binder Systems for High-Energy, High-Power Lithium-Ion Batteries

Abstract

Developing high-performance battery systems requires the optimization of every battery component, from electrodes and electrolyte to binder systems. However, the conventional strategy to fabricate battery electrodes by casting a mixture of active materials, a nonconductive polymer binder, and a conductive additive onto a metal foil current collector usually leads to electronic or ionic bottlenecks and poor contacts due to the randomly distributed conductive phases. When high-capacity electrode materials are employed, the high stress generated during electrochemical reactions disrupts the mechanical integrity of traditional binder systems, resulting in decreased cycle life of batteries. Thus, it is critical to design novel binder systems that can provide robust, low-resistance, and continuous internal pathways to connect all regions of the electrode. Here in this Account, we review recent progress on material and structural design of novel binder systems. Nonconductive polymers with rich carboxylic groups have been adopted as binders to stabilize ultrahigh-capacity inorganic electrodes that experience large volume or structural change during charge/discharge, due to their strong binding capability to active particles. To enhance the energy density of batteries, different strategies have been adopted to design multifunctional binder systems based on conductive polymers because they can play dual functions of both polymeric binders andmore » conductive additives. We first present that multifunctional binder systems have been designed by tailoring the molecular structures of conductive polymers. Different functional groups are introduced to the polymeric backbone to enable multiple functionalities, allowing separated optimization of the mechanical and swelling properties of the binders without detrimental effect on electronic property. Then, we describe the design of multifunctional binder systems via rationally controlling their nano- and molecular structures, developing the conductive polymer gel binders with 3D framework nanostructures. These gel binders provide multiple functions owing to their structure derived properties. The gel framework facilitates both electronic and ionic transport owing to the continuous pathways for electrons and hierarchical pores for ion diffusion. The polymer coating formed on every particle acts as surface modification and prevents particle aggregation. The mechanically strong and ductile gel framework also sustains long-term stability of electrodes. In addition, the structures and properties of gel binders can be facilely tuned. We further introduce the development of multifunctional binders by hybridizing conductive polymers with other functional materials. Meanwhile mechanistic understanding on the roles that novel binders play in the electrochemical processes of batteries is also reviewed to reveal general design rules for future binder systems. We conclude with perspectives on their future development with novel multifunctionalities involved. Highly efficient binder systems with well-tailored molecular and nanostructures are critical to reach the entire volume of the battery and maximize energy use for high-energy and high-power lithium batteries. We hope this Account promotes further efforts toward synthetic control, fundamental investigation, and application exploration of multifunctional binder materials.« less

Authors:

Shi, Ye ^[1]; Zhou, Xingyi ^[1]; Yu, Guihua  ^[1]

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1. Materials Science and Engineering Program and Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States

Publication Date:

Thu Oct 05 00:00:00 EDT 2017

Research Org.:

Stony Brook Univ., NY (United States). Research Foundation for The State University of New York; Energy Frontier Research Centers (EFRC) (United States). Center for Mesoscale Transport Properties (m2M)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

Contributing Org.:

Energy Frontier Research Center (EFRC). Center for Mesoscale Transport Properties

OSTI Identifier:

1398136

Alternate Identifier(s):

OSTI ID: 1413260

Grant/Contract Number:  

SC0012673

Resource Type:

Published Article

Journal Name:

Accounts of Chemical Research

Additional Journal Information:

Journal Name: Accounts of Chemical Research Journal Volume: 50 Journal Issue: 11; Journal ID: ISSN 0001-4842

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

25 ENERGY STORAGE