A Highly Damping, Crack-Insensitive and Self-Healable Binder for Lithium-Sulfur Battery by Tailoring the Viscoelastic Behavior

Binder plays an important role in maintaining the integrity of sulfur electrode in lithium-sulfur (Li-S) battery. However, cracks are easily generated inside the electrode and compromise its performance due to the volume change of sulfur during redox reaction and continuous vibration originated from the external environments. It is a challenge yet crucial to develop tough binders with crack-insensitivity and damping performance. Herein, a polymeric binder is designed with special viscoelastic behavior by tailoring its electrolyte-philic and electrolyte-phobic domains. The loss modulus of the binder is regulated to be highly close to its storage modulus within a wide range of frequency, generating an ultra-high loss factor and equilibrium of viscosity-elasticity. Based on such rheological behavior, the binder holds 1) high damping ability across a wide frequency to suppress crack generation, 2) high toughness with crack blunting behavior to resist crack propagation, 3) efficient healing capability to repair the cracks. Besides, the pendant zwitterionic groups can immobilize the lithium polysulfides and promote ion transfer. Benefiting from these advantages, the obtained Li-S battery delivers high specific capacity with considerable capacity retention after long-term cycling. The viscoelastic design and crack management strategy illustrated here would provide new insights into the binder design. A binder has been developed with special viscoelastic balance by tailoring the electrolyte-philic and electrolyte-phobic segments, which achieves crack insensitivity, self-healing capacity, lithium polysulfides adsorption, and ion transfer promotion. The obtained Li-S battery exhibits high specific capacity and stable cycling performance. This study believes such binder with multiple crack management mechanism will provide new insights for the development of Li-S battery. image