Thermoplastic Polyurethane Derived from CO 2 for the Cathode Binder in Li-CO 2 Battery.

High-energy-density Li-CO 2 batteries are promising candidates for large-capacity energy storage systems. However, the development of Li-CO 2 batteries has been hindered by low cycle life and high overpotential. In this study, we propose a CO 2 -based thermoplastic polyurethane (CO 2 -based TPU) with CO 2 adsorption properties and excellent self-healing performance to replace traditional polyvinylidene fluoride (PVDF) as the cathode binder. The CO 2 -based TPU enhances the interfacial concentration of CO 2 at the cathode/electrolyte interfaces, effectively increasing the discharge voltage and lowering the charge voltage of Li-CO 2 batteries. Moreover, the CO 2 fixed by urethane groups (-NH-COO-) in the CO 2 -based TPU are difficult to shuttle to and corrode the Li anode, minimizing CO 2 side reactions with lithium metal and improving the cycling performance of Li-CO 2 batteries. In this work, Li-CO 2 batteries with CO 2 -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-CO 2 batteries.