Construction of dual crosslinked network binder via sequential ionic crosslinking for high-performance silicon anodes

Hybrid Ionically Covalently Cross-Linked Network Binder for High-Performance Silicon Anodes in Lithium-Ion Batteries

“…Ammonia not only acted as a "switch", but also improved the flow properties of the CMC-NH 3 -HBPEI solution. Figure 2a shows the viscosity changes of CMC, HBPEI and CMC-NH 3 -HBPEI aqueous solutions over 72 h. HBPEI has the lowest viscosity in aqueous solution due to its hyperbranched structure and low molecular weight (Figure 2a) [21,25]. In contrast, the linear polymer CMC presents a higher viscosity value (Figure 2a) [21,26].…”

“…The chemical composition of the samples was characterized by FTIR (Bruker tensor 27, Billerica, MA, USA). In addition, the conversion between the ionic and covalent bonds of the CMC-HBPEI films was analyzed by XPS (Thermo Scientific 250) using monochromatic Al Kα radiation (primary energy E = 1486.6 eV) with a passage energy of 100 eV [21].…”

“…The coin cells (CR2025) used 1 M LiPF6 in a 1:1:1 volume ratio mixture of the vinyl carbonate, diethyl carbonate, and dimethyl carbonate as the electrolyte, Li foil as the counter electrode, and the prepared Si anode foil was punched into a 12 mm diameter disk as the working electrode [21]. The coin cells were assembled in an argon-filled glove box.…”

“…For the cycling test, the current density was kept at 500 mA g −1 , while for the rate test, the current density varied from 250 to 2000 mA g −1 . Electrical impedance spectroscopy (EIS) tests were performed by applying a sinusoidal signal with an amplitude of 10 mV over a frequency range of 0.01 to 100 kHz using an electrochemical workstation (CHI, 660E) [21]. The topographical changes and distribution of elements in the Si anodes before and after cycling were examined using a combination of FESEM and EDX (Thermo Scientific, Apreo 2, Waltham, MA, USA).…”

“…In this study, carboxymethyl cellulose (CMC) and hyperbranched polyethyleneimine (HBPEI) were chosen as the primary binder materials. CMC, a linear polymer containing carboxymethyl groups, can serve as the skeleton of the composite binder [19], while HBPEI, a hyperbranched polymer containing numerous amino groups, can provide abundant hydrogen bonding sites for the composite binder [20,21]. The combination of CMC and HBPEI can create a mechanically stable and strongly adhesive binder material.…”