Leveraging Piezoelectric and Ferroelectric Effects to Control Zinc Deposition for High-Performance Solid-State Zinc Batteries

Solid electrolytes with piezoelectric and ferroelectric properties can form stable interface structures through spontaneous polarization under electrostatic potential differences. The presence of a ferroelectric polarization electric field can reduce the initial electrostatic potential difference and minimize adverse ion aggregation in the electrical double layer (EDL). Herein, we integrated piezoelectric and ferroelectric CaBi2Nb2O9 (CBN) sheets into a solid polymer electrolyte (SPE) based on a poly(vinylidene difluoride) (PVDF) matrix, which is referred to as CBN@PVDF. Experimental results and theoretical simulations reveal that the piezoelectric effect of the CBN, induced by mechanical stress during zinc plating, can diminish the driving force for dendrite growth in regions of high curvature. Simultaneously, its ferroelectric properties can lower the local overpotential, resulting in even deposition of Zn. As expected, the symmetric Zn|CBN@PVDF|Zn batteries exhibit unprecedented cycling stability, achieving lifespans of 2000 h at 0.5 mA cm-2, and 1500 h at 1.0 mA cm-2, respectively. In addition, incorporating CBN could enhance the dielectric properties of the SPE, improve salt dissociation, and increase the ionic conductivity of the SPE, thereby achieving a superior rate performance for Zn||pyrene-4,5,9,10-tetraone (PTO) solid full cells. It can function at an exceptionally high rate of 10 C, achieving a high specific capacity of 221 mAh g-1. Overall, designing piezoelectric/ferroelectric SPEs can effectively address the challenges of nonuniform Zn deposition and low ionic conductivity of SPE, providing a robust foundation for the development of high-performance solid-state zinc batteries.