A conductive self healing polymeric binder using hydrogen bonding for Si anodes in lithium ion batteries

Abstract

A ureido-pyrimidinone (UPy)-functionalized poly(acrylic acid) grafted with poly(ethylene glycol)(PEG), designated PAU-g-PEG, was developed as a high performance polymer binder for Si anodes in lithium-ion batteries. By introducing both a ureido-pyrimidinone (UPy) unit, which is capable of self-healing through dynamic hydrogen bonding within molecules as well as with Si, and an ion-conducting PEG onto the side chain of the poly(acrylic acid), this water-based self-healable and conductive polymer binder can effectively accommodate the volume changes of Si, while maintaining electronic integrity, in an electrode during repeated charge/discharge cycles. The Si@PAU-g-PEG electrode retained a high capacity of 1,450.2 mAh g−1 and a Coulombic efficiency of 99.4% even after 350 cycles under a C-rate of 0.5 C. Under a high C-rate of 3 C, an outstanding capacity of 2,500 mAh g−1 was also achieved, thus demonstrating its potential for improving the electrochemical performance of Si anodes.

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

“…Furthermore, Kim et al designed a UPy functionalized PAA grafted with PEG (PAU‐ g ‐PEG) binder for SiNP anodes by free radical copolymerization of tert ‐butyl acrylate monomer, Upy‐containing monomer and poly(ethylene glycol) methyl ether methacrylate monomer followed by hydrolysis (Figure 19B). 161 The coexistence of UPy and PEG units imparted the PAU‐ g ‐PEG binder with excellent self‐healing property, improved adhesive strength and high ionic conductivity, rendering the Si anodes with excellent cycling (capacity retention of 1450.2 mA h g −1 and CE of 99.4% after 350 cycles under a C‐rate of 0.5 C) and rate (capacity of 2500 mA h g −1 under a C‐rate of 3 C) performances.…”

“…Copyright 2018, WILEY‐VCH. (B) Schematic illustrations of the PAU‐ g ‐PEG binder with both self‐healing and Li ion conductive properties, compared with PAA‐ g ‐PEG with only Li ion conductive property; Adhesive properties and cycling performances of the SiNP electrodes using PAU‐ g ‐PEG, PAA‐ g ‐PEG, and PAA as binders 161 . Copyright 2020, Springer Nature…”

“…Finally, SiMP anodes with the PAA‐P(HEA‐ co ‐DMA) binder exhibited excellent cycling performances under even a high electrode loading (1.74 mg cm −1 ). Besides, the combination of self‐healing and ionic conductivity will render binder with both self‐healing property and high ionic conductivity, enabling the greatly improved cycling and rate performances of Si‐based anodes 45,161 . Zhou et al developed a composite polymer binder with both high ionic and electronic conductivities by assembling ionic conductive polymers (PEO and PEI) onto the electronically conductive polymer chains (PEDOT: PSS), to promote the superior cycling performances of SiNP anodes (Figure 28C).…”

“…(B) Schematic illustrations of the PAU-g-PEG binder with both self-healing and Li ion conductive properties, compared with PAA-g-PEG with only Li ion conductive property; Adhesive properties and cycling performances of the SiNP electrodes using PAU-g-PEG, PAA-g-PEG, and PAA as binders. 161 Copyright 2020, Springer Nature polyethylene glycol diacrylate (PEGdA) monomer. After adding FeCl 3 (in a molar ratio of catechol/Fe 3+ = 3:1) into PDBP solution and increasing the pH value to 10, Fe 3+ -(tris) catechol coordinated self-healing metallopolymer binder could be obtained, which is denoted as Fe-PDBP@pH 10.…”

Polymer Binders: Characterization and Development toward Aqueous Electrode Fabrication for Sustainability

“…It is important to note that during cycling, the electrolyte may decompose and deposit a solid layer onto the electrode called the solid electrolyte interface (SEI)—this would present itself as another source of resistance (abbreviated as R SEI ) in the high-frequency region after cycling. A capable binder would allow for the retention of a dense film that could mitigate the thickness of the SEI formed [ 29 , 38 ]. Furthermore, EIS can also be used to model the interfacial resistance at the current collector/electrode interface, which would be observed in the high-frequency region of Nyquist plots [ 39 ].…”