Room-Temperature Rapid Self-Healing Polymer Binders for Si Anodes in Highly Cycling-Stable and Capacity-Maintained Lithium-Ion Batteries

Abstract

Silicon (Si) with high specific capacity has received increasing attention for rechargeable battery anode materials. However, particle pulverization as a result of the large volume expansion of Si anodes further aggravated electrochemical performance degradation during the process of charging and discharging. In this work, we report the room-temperature rapid self-healing polymer binders (Al/Alg-TUEG) synthesized via dynamic coordination bonds (Al–O) and hydrogen bonds from poly(ether-thioureas) (TUEG). The prepared polymer binders exhibit a peeling force of 4.2 N, a swelling ratio of 9.5%, and a recovery of 90% in 2 h at room temperature. As a result, the Si@Al/Alg-TUEG anodes stably cycle for 300 cycles at 0.5 C with a capacity retention rate of 77.4%. A high initial Coulombic efficiency (CE) of 87.2% and good rate performance are also achieved. In terms of full cell performance, both LiFePO4//Si@Al/Alg-TUEG and NCM811//Si@Al/Alg-TUEG display stable cycling for 100 cycles at 0.5 C. The capacity retention of both full cells reaches 93.8 and 92.5%. Good recoverability at high rates is also found. The superior electrochemical performance of the Si anode indicates that Al/Alg-TUEG polymer with rapid self-healing capability at room-temperature is one of the promising binder candidates for next-generation high-energy-density lithium-ion batteries.

Interconnected Multifunctional Waterborne Polyurethane Binder for Structural Robustness of Si Anodes in Lithium-Ion Batteries

“…62 After the 100th cycle, XPS characterization was performed to investigate the components of the SEI layer of each Si anode. As presented in Figure 4c,d 63 According to the previous results, the formation of Li 2 CO 3 , C−O, and C=O peaks is attributed to the decomposition of electrolytes which are based on organic carbonate. 64 As indicated by the C 1s spectra, the Li 2 CO 3 and O-containing peaks were observed in both Si anodes, but the Si anode with the PVDF binder showed a more pronounced intensity in these peaks compared to that of the Si anode with the TMPU binder.…”

“…As presented in Figure c,d, the C 1s and F 1s XPS spectra identified the chemical composition of the SEI layer covered on the Si anode surface. The C 1s spectra were divided into four peaks: C–C (284.8 eV), C–O (286.4 eV), C=O (288.1 eV), and Li 2 CO 3 (289.6 eV) . According to the previous results, the formation of Li 2 CO 3 , C–O, and C=O peaks is attributed to the decomposition of electrolytes which are based on organic carbonate .…”

Robust Polyurethane Binders Intensified by Hydrogen Bonding, a Dynamic S–S Bond, and Metal-Ion Coordination for Silicon Anodes

“…After the activation cycle, the Coulombic efficiency of Si/PDA-M-BFPU could be stabilized to above 98%. This indicates that PDA-M-BFPU can improve ICE and form a uniform and stable SEI layer to ensure the stable cycle of the battery. ,− As shown in Figure b, the rate performances of Si/PDA-M-BFPU and Si/PDA-BFPU were tested at current densities of 0.1 0.2, 0.3, 0.5, 1, 2, and 3 C. The specific capacities of Si/PDA-Al-BFPU, Si/PDA-Fe-BFPU, and Si/PDA-Zn-BFPU at 0.1 C were 3631.8, 3500.0, and 3381.4 mAh·g –1 , while the specific capacity of Si/PDA-BFPU was lower at 3207.7 mAh·g –1 . Also, the specific capacity of Si/PDA-BFPU dropped to 0 mAh·g –1 at 2 C. When the current density was reduced to 0.1 C again, it was surprising to find that the specific capacities of Si/PDA-M-BFPU recovered.…”

“…The calculation of lithium-ion diffusion coefficients was detailed in our previous study. 59 The ion diffusion coefficients of Si/PDA-Zn-BFPU, Si/PDA-Fe-BFPU, and Si/PDA-Al-BFPU were calculated to be 7.854 × To visualize the effect of different binders in suppressing the volume expansion of Si particles, the surface and crosssectional morphology of the electrodes before and after 100 cycles was analyzed by SEM. As shown in Figure 7a−d, the surfaces of the electrodes before cycling were dense and smooth without cracks, and the uniformly dispersed pores on the surfaces were conducive to penetration of the electrolyte and diffusion of Li + .…”

“…On this basis, a linear relationship between the peak current ( i p ) and the square root of the scan rate ( v 0.5 ) was fitted, as shown in Figure b. The calculation of lithium-ion diffusion coefficients was detailed in our previous study . The ion diffusion coefficients of Si/PDA-Zn-BFPU, Si/PDA-Fe-BFPU, and Si/PDA-Al-BFPU were calculated to be 7.854 × 10 –12 , 2.797 × 10 –11 , and 1.724 × 10 –10 cm 2 ·s –1 , respectively.…”