Researchers in China have designed a 3D-crosslinked binder with ultralow-content (1 wt%) that not only endures the huge volume variation of silicon anodes under charge/discharge cycles but also enhance electrochemical performance. A paper on their work is published in Journal of Power Sources.

High-content binders (10–50 wt%) are often noted as effective methods to stabilize silicon anodes; however, these usually lead to a low energy density under the same electrode loading, the researchers noted.

The new 3D-crosslinked binder (LiCMC-TA) is synthesized using the partially lithiated Carboxymethyl Cellulose Sodium (LiCMC) as a skeleton structure and Tannic Acid (TA) as cross-linker via multiple hydrogen bonding interactions.

Lithium-ions are quickly transferred via partially lithiated groups of LiCMC-TA binder. The highly branched TA is introduced to construct a network of multiple hydrogen bonds. The binder can relieve the stress of silicon through continuing cleavage of the the multiple hydrogen bons.

Tang et al.

Density Functional Theory simulations indicate that the main hydrogen bonds energies changed from −4.11 eV (CO⋯H–O–C) to −1.997 eV (CO⋯H–O-Ph), which further verify the existence of multiple hydrogen bonds. The LiCMC-TA binder provides efficient stress dissipation, which exhibits high initial Coulombic efficiency (80.65%) and excellent reversible capacity (1701 mAh g⁻¹ after 150 cycles at 1 A g⁻¹), making Si anodes more promising for practical applications, the researchers said.

Resources

• Bo Tang, Shenggong He, Yayu Deng, Yan Shan, Haiqing Qin, Hadia Noor, Xianhua Hou (2022) “Advanced binder with ultralow-content for high performance silicon anode,” Journal of Power Sources, Volume 556, doi: 10.1016/j.jpowsour.2022.232237.