Investigations of Intramolecular Hydrogen Bonding Effect of a Polymer Brush Modified Silicon in Lithium‐Ion Batteries
Alem Gebrelibanos Hailu, Alagar Ramar, Fu‐Ming Wang, Nae‐Lih Wu, Nan‐Hung Yeh, Chun‐Chuan Hsu, Yung‐Jen Chang, Lester Tiong, Rio Akbar Yuwono, Chusnul Khotimah, Chun‐Chieh Wang
Abstract
Abstract Silicon (Si) has the maximum capacity compared with the conventional graphite, which can dramatically increase the energy density of the battery. However, due to some tremendous drawbacks of Si material such as electrochemical irreversibility and volume expansion on alloy reaction, pure Si cannot be used in large quantities in the anode electrode. In this research, a polymer brush core‐shell structure (PBCS) on Si nanoparticle provides three significant functions because of the intramolecular effect of hydrogen bonding with PBCS and the binder delivers a good dispersion in the slurry, a mechanical protection during cycling, and excellent ionic conductivity for high‐rate tests. The carbonyl groups of polymer brush on Si surface are fabricated to enhance lithium‐ion diffusion and the adjustment of attraction and repulsion by intramolecular hydrogen bonding effect with binder in between each Si particles. The PBCS‐Si electrode shows the first coulombic efficiency is 87.1%; the retentions are 92.5% (0.1C/ 0.1C) for 200 cycles and 86.2% (0.5C/ 0.5C) for 400 cycles. Operando TXM displays that the PBCS structure significantly protects the nano Si from cracking owing to the high elastic function and intramolecular hydrogen bonding effect of the PBCS. With this novel PBCS‐Si material, a high energy density lithium‐ion battery can be expected.