Thermoplastic Polyurethane Derived from CO₂ for the Cathode Binder in Li-CO₂ Battery

High-energy-density Li-CO₂ batteries are promising candidates for large-capacity energy storage systems. However, the development of Li-CO₂ batteries has been hindered by low cycle life and high overpotential. In this study, we propose a CO₂-based thermoplastic polyurethane (CO₂-based TPU) with CO₂ adsorption properties and excellent self-healing performance to replace traditional polyvinylidene fluoride (PVDF) as the cathode binder. The CO₂-based TPU enhances the interfacial concentration of CO₂ at the cathode/electrolyte interfaces, effectively increasing the discharge voltage and lowering the charge voltage of Li-CO₂ batteries. Moreover, the CO₂ fixed by urethane groups (-NH-COO-) in the CO₂-based TPU are difficult to shuttle to and corrode the Li anode, minimizing CO₂ side reactions with lithium metal and improving the cycling performance of Li-CO₂ batteries. In this work, Li-CO₂ batteries with CO₂-based TPU as the multifunctional binders exhibit stable cycling performance for 52 cycles at a current density of 0.2 A g^-1, with a distinctly lower polarization voltage than PVDF bound Li-CO₂ batteries.