Porous Composite Bifunctional Membranes for Lithium‐Ion Battery Separator and Photocatalytic Degradation Applications: Toward Multifunctionality for Circular Economy

Abstract

Circular economy paradigms will benefit materials with multifunctional properties allowing to be implemented in more than one application, after processed, or in one application after already being used in another. In this context, membranes based on TiO2/poly(vinylidene fluoride‐co‐trifluoroethylene) (PVDF‐TrFE) with different filler contents were prepared for battery and photocatalytic degradation of pollutants by a temperature‐induced phase separation process (TIPS). It has been shown that the morphological, thermal and mechanical properties, porosity, contact angle, the ionic conductivity and lithium transference number are dependent on the TiO2 content. The membranes with 10 wt% TiO2 content show an ionic conductivity of 0.59 mS cm−1, lithium transference number of 0.72, discharge capacity of 128 mAh g−1 and low capacity fade (17%) at 2C. Further, this membrane presents a high photocatalytic response, being able to be used for ciprofloxacin remediation from water after 300 min of exposure to UV. Further, a second life was confirmed for this membrane by being implemented as a lithium ion battery separator after its use for water remediation applications. This work explores a new concept for the efficient use of the same membranes in very different applications, demonstrating the multifunctionality of the material in the scope of the circular economy paradigm.