A fluorine-absorbing and mechanically elastic binder with triangular architecture enables both bulk- and interface-stable Si anodes

Abstract: Mechanically robust polyacrylic acid (PAA) binders are extensively investigated for improving the structural stability and extending the cycle life of Si anodes. However, PAA cannot simultaneously suppress interfacial side reactions, preserve structural integrity, and ensure efficient ion transport. This paper presents a mechanically elastic polymeric binder, PCZn, that integrates locally positive charges to introduce a LiF-rich interface and high ionic conductivity within a triangular architecture established through the triadic interaction of a long-chain PAA adhesive, cross-linking agent chitosan oligosaccharide, and cation donor zinc gluconate. PCZn imparts a highly reversible anti-strain capability, a conformal LiF-rich solid-electrolyte-interface layer, and high ionic conductivity to Si anodes, resulting in remarkable electrochemical performance with a high capacity of 1210 mAh g-1 after 450 cycles at 3 A g-1 and enhanced fast-charging capability of 1468 mAh g-1 at 8 A g-1. Thus, concurrently addressing mechanical failure, interfacial instability, and sluggish kinetics of Si anodes through advanced binder design will help develop high-energy-density next-generation batteries with long cycle lives. Dataset description: PNG data from original research within the project EBEAM. Precisely there are six final, complex Figures plus one PDF file with supporting information below: Fig. 1 (a) Schematic illustrations showing the operation of Si electrodes with different binders during cycling. (b) Molecular structure and interactions among chains of PCZn binder. (c) Illustration of the formation process of LiF-rich SEI derived from the interaction between PCZn binder and electrolyte. Fig. 2 (a) FTIR spectra of PCZn, PAA, COS, and ZnGa. (b) C 1s high-resolution XPS spectra of PCZn and PAA. (c) Calculated energies of gradient hydrogen bonds and covalent bonds. (d) DSC curves of PCZn and PAA. (e) Shear viscosities of PCZn and PAA solutions (2 wt percent). (f) LiPLUS conductivity of PCZn and PAA. (g) Stress–strain curves of PCZn and PAA. (h) HADDF and EDS mappings of Si–PCZn. (i) High-resolution TEM image of Si–PCZn. Fig. 3 (a) Load-indentation depth curves, (b) hardness and modulus values determined using nano-indentation tests, (c) peeling test results, and (d)–(i) DMT modulus, adhesion, and dissipation mapping results for Si–PCZn and Si–PAA electrodes. Fig. 4 (a) CV curves of Si–PCZn and Si–PAA electrodes and (b) enlarged curves for the first cycle. (c) Charge–discharge curves of Si–PCZn and Si–PAA electrodes at a current density of 0.3 A g−1 . Cycling performance of Si–PCZn and Si–PAA electrodes at current densities of (d) 0.6 and (e) 3Ag−1 . (f) Charge–discharge curves of the Si–PCZn electrode at a current density of 3 A g−1 . (g) Rate performance of Si–PCZn and Si–PAA electrodes. (h) Comparison of the electrochemical performance of the Si–PCZn anode with previous reports for Si-based anodes. (i) Cycling performance of Si–PCZn‖NCM811 and Si–PAA‖NCM811full cells at 0.5C. (j) Charge–discharge profiles for the fourth, tenth, 20th, 50th and 100th cycles of the Si–PCZn‖NCM811 full cell. (k) Voltage polarization curves of Si–PCZn‖NCM811and Si–PAA‖NCM811 full cells. Fig. 5 (a)–(c) EIS spectra and fitted results for the Si–PCZn and Si–PAA electrodes after different numbers of cycles. (d) CV curves of Si–PCZn under different sweep rates from 0.1 to 1 mV s−1 . (e) Plots of CV peak current versus the square root of the scanning rates. (f) Capacitance contributions of the Si–PCZn electrode at various sweep rates. (g) GITT test results for the Si–PCZn and Si–PAA electrodes. (h) Li-ion diffusion rates calculated for the Si–PCZn and Si–PAA electrodes. Fig. 6 High-resolution XPS spectra of (a) and (b) Si 2p and (c) and (d) F 1s from cycled Si electrodes. TEM image and corresponding EDS mapping of (e) Si–PCZn and (f) Si–PAA electrodes after 50 cycles. (g) Dipole–dipole interaction between ZnGa and FEC and ZnGa and PF6 −. (h) Charge density differences between COS and PAA. Funding: National Natural Science Foundation of China (Grant No. 52071225) European Union's Horizon Europe research and innovation program under grant agreement No. 101087143 (Electron Beam Emergent Additive Manufacturing (EBEAM)) National Key R&D Program of China (Grant No. 2021YFB3800300) National Natural Science Foundation of China (Grant No. 22179143 and 22002176) National Science Center, Norway (Grant Project No. 2019/34/H/ST8/00547)