Review—Conducting Polymer-Based Binders for Lithium-Ion Batteries and Beyond

Abstract

In the search for active Lithium-ion battery materials with ever-increasing energy density, the limits of conventional auxiliary materials, such as binders and conducting additives are being tested. Binders adhere to active substances and current collectors, yielding an interconnected electrode structure that ensures mechanical integrity during the (de-)lithiation process. Even though the battery binder only accounts for a fraction of battery weight and cost, it is a bottleneck technology in the deployment of high energy density active materials that experience significant volume variation and side-reactions. This review paper discusses research on alternative binders derived from conducting polymers (CPs). The use of CPs in binders enables mechanically flexible electronic contacts with the active material with the goal of accommodating larger volume changes within the electrode. Following a summary of the reasoning behind the use of CP-based binders, their rational design is reviewed, including novel composite syntheses and chemical modifications. A new class of multifunctional CP-based binders exhibits promising properties such as high electronic conductivity, the ability for aqueous processing, and efficient binding that tackle the limiting features of traditional binders. The practical application of these binders in Li-ion batteries and beyond is summarized, yielding an outline of current achievements, and a discussion of remaining knowledge gaps and possible future development of such binders.

Advances of polymer binders for silicon‐based anodes in high energy density lithium‐ion batteries

“…Using conductive polymer binders as both binder and conductive agent are expected to maintain the overall electrode conductivity, and meanwhile boost the energy density of cell by increasing the proportion of active material in the electrode. Many reports have demonstrated that the conductive polymer binders with high electrical conductivity and strong binding ability can promote improved cycling performances of Si‐based anodes at high areal capacities 178‐180 …”

Nano‐Scale Complexions Facilitate Li Dendrite‐Free Operation in LATP Solid‐State Electrolyte

“…From this contrast three regions can be differentiated: the crystalline LATP grains, thin and darker semi-amorphous regions to both sides at the crystalline grain interface, and a brighter amorphous region in the grain boundary center. Both grains are oriented in [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] hex zone axis. The highly symmetric bright reflexes in Figure 1c correspond to a [100] pc pseudocubic sublattice commonly assigned to partially occupied Li positions in the LATP crystal structure.…”

“…This is mainly due to mechanochemical, chemical, and electrochemical stability issues and interfacial processes that have severely compromised any proposed cell's lifetime. [7][8][9][10][11] While many SSE material inherent (mechano-)chemical processing issues seem amenable to modern engineering approaches, [12][13][14][15][16][17][18][19] the situation is less bright regarding the control of interfacial chemical and electrochemical stability (especially when featuring a LMA), as well as ionic and electronic transport quantities across these interfaces. A hitherto missing deep understanding of the structural, chemical, and physical properties of the buried solid-solid interfaces inside ASSBs at the atomic level is required to overcome these performance limiting interfacial issues.The most studied interfacial properties so far are contact stability and dendrite nucleation and growth.…”

Recent Insights into Rate Performance Limitations of Li‐ion Batteries

“…The optimal amount of active material is around 90 %; binder and conductive additives (carbon black) range between 2 and 8 %, depending on the battery type and conditions of use. Besides the established carbon black, perspective conductive additives such as carbon nanotubes, [27] graphene [28] and conductive polymers [29] are studied. Generally, these components allow to increase the weight ratio of the active material, without compromising the conductivity of the composite electrode and thus the rate performance.…”