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. 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 and 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. We then 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-tailor...

3D Network Binder via In Situ Cross‐Linking on Silicon Anodes with Improved Stability for Lithium‐Ion Batteries

“…The common approach is to synthesize nanostructured or porous Si, which has more buffering space compared with bulk Si . As one of the three major components in an electrode, the polymer binder is used to connect active materials and conductive agent together and sticking them onto the current collector . The properties of the polymer binder have a great impact to the electrochemical performance of the electrode materials, especially for the cycling stability and irreversible capacity losses.…”

“…[8][9][10][11][12][13] As one of the three major components in an electrode, the polymer binder is used to connect active materials and conductive agent together and sticking them onto the current collector. [14][15][16][17][18] The properties of the polymer binder have a great impact to the electrochemical performance of the electrode materials, especially for the cycling stability and irreversible capacity losses. Traditional polyvinylidene difluoride (PVDF) binder is unsuitable for Si anodes.…”

A Quadruple‐Hydrogen‐Bonded Supramolecular Binder for High‐Performance Silicon Anodes in Lithium‐Ion Batteries

“…[14][15][16][17] In addition, the low discharge voltage and better safety enable silicon to be one of the most promising candidate of anodic material for new LIBs with high energy density and long cycling life. [18] However, silicon undergoes extreme volume expansion/shrink (420%) during the repeated lithiation/delithiation process, causing extensive fracturing and fragmentation, followed by the deterioration of electrical contact with the bulk electrode, resulting in the rapid decrease of capacity and poor cycling stability. [19][20][21][22] Although the nanosizing strategies of Si could accommodate the volume With extremely high specific capacity, silicon has attracted enormous interest as a promising anode material for next-generation lithium-ion batteries.…”

A Water‐Soluble NaCMC/NaPAA Binder for Exceptional Improvement of Sodium‐Ion Batteries with an SnO2‐Ordered Mesoporous Carbon Anode

“…[22][23][24][25][26] Cost-effectiveness and large-scale applications are emphasized for NIBs. [22][23][24][25][26] Cost-effectiveness and large-scale applications are emphasized for NIBs.…”

“…tracted al ot of attention for LIBs and NIBs owing to their low cost, nontoxicity,s hort drying time, easy processing, and great bondinga bility. [22][23][24][25][26] Cost-effectiveness and large-scale applications are emphasized for NIBs. Therefore, the use of appropriate andi nexpensive binders to improve battery performance is more desirable than developing sophisticateda ctive materials for the same purpose.…”