Heavy-Duty Performance from Silicon Anodes Using Poly(BIAN)/Poly(acrylic acid)-Based Self-Healing Composite Binder in Lithium-Ion Secondary Batteries

Abstract

Natural abundance and high theoretical capacity make silicon a promising anode material in Li-ion batteries (LIBs). However, repeated cycling causes the pulverization of Si particles due to the large volume expansion that results in their rapid breakdown, delamination from the current collector, loss of electrical contact, and thick solid–electrolyte interphase (SEI) formation. This results in their poor performance. To overcome these drawbacks, the application of functional polymers as binders to silicon anodes has emerged as a competitive strategy. In this regard, here, the design, synthesis, and application of a highly robust n-type self-healing polymer composite poly­(bisiminoacenaphthenequinone)/poly­(acrylic acid) (P-BIAN/PAA) as a binder for Si anodes is reported. On its application, P-BIAN/PAA was evaluated to (i) provide mechanical robustness to the large volume expansion of Si particles, (ii) maintain electrical conductivity within the electrode laminate, and (iii) facilitate the formation of a thin SEI by restricting the extent of electrolyte decomposition on the surface of anode because of its low-lying lowest unoccupied molecular orbital (LUMO) that empowers its n-doping in the reducing environment. As a result, Si anodes could be stabilized for over 600 cycles of charge–discharge with a high reversible capacity of about 2100 mAh g–1 Si, ∼95% capacity retention, and >99% Coulombic efficiency. The extent of suppression of electrolyte decomposition that led to a facile and thin interphase-SEI and the corresponding interfacial components with respective impedance values were not only theoretically evaluated but also supported by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and dynamic-EIS. Further, the postmortem characterization of the anode by X-ray photoelectron spectroscopy (XPS) justified the thin SEI formation on Si anode with P-BIAN/PAA composite binder.

BIAN-based durable polymer metal complex as a cathode material for Li–O2 battery applications

“…4. The BP copolymer had only the pyridinic-type nitrogen for the imine and exhibited a binding energy of 399.1 eV [45]. Upon complexation, two types of nitrogen were possible based on the contents of complex and unreacted imine.…”

Enabling Ultrafast Charging in Graphite Anodes Using BIAN-Based Conjugated Polymer/Lithium Polyacrylate as a Binder

“…5,9−11 current collector, and (c) the conjugated network of the polymer is provided by the BIAN-phenylene moiety as a component of the polymeric backbone, ensuring better electronic conductivity across the electrode matrix. 5,10 However, the Li + ion diffusion, R CT , and activation energy of lithiation of the anode can be further improved to enable XFC through additional binder design. The addition of LiPAA to bis(imino)acenaphthene quinoneparaphenylene copolymer (P-BIAN) makes the reported composite binder more robust because LiPAA introduces a Li + ion reservoir that greatly promotes Li + ion diffusion and improves the activation energy of lithiation of the anode.…”

Ion-Conducting Cross-Linked Polyphosphazene Binders for High-Performance Silicon Anodes in Lithium-Ion Batteries

“…With the increasing development of electric vehicles, portable devices, and energy storage systems, considerable attention is being paid to improving the energy density of lithium-ion batteries (LIBs). − Although graphite-based materials are the most commonly used materials for anodes in commercial LIBs, the improvement in energy density is limited due to their relatively low theoretical capacities (e.g., capacity = 372 mA h g –1 based on LiC 6 ) . Silicon has been considered as a promising anode material due to its high theoretical capacity (4200 mA h g –1 ), low discharge potential (∼0.3 V vs Li/Li + ), and natural abundance. − However, since Si undergoes a significant volume change of up to 300% during charging/discharging, the electrode structure is degraded, and a thick solid–electrolyte interface (SEI) layer is formed, which is the critical disadvantage in practical application of the Si anodes. , One of the main strategies to mitigate the Si volume change is to adopt nanostructured Si as the anode material, such as yolk–shell nanoparticles, , nanowires, , and nanoporous structures. , Although nanostructured Si anodes have been known to reduce Si volume expansion to some extent, the commercialization of these materials is hampered by high production costs and difficulty in scaling-up the manufacturing process …”