Multifunctional All-Inorganic Flexible Capacitor for Energy Storage and Electrocaloric Refrigeration over a Broad Temperature Range Based on PLZT 9/65/35 Thick Films

Multifunctional capacitors can efficiently integrate multiple functionalities into a single material to further down-scale state-of-the-art integrated circuits, which are urgently needed in new electronic devices. Here, an all-inorganic flexible capacitor based on Pb 0.91 La 0.09 (Zr 0.65 Ti 0.35 ) 0.9775 O 3 (PLZT 9/65/35) relaxor ferroelectric thick film (1 μm) was successfully fabricated on LaNiO 3 /F-Mica substrate for application in electrostatic energy storage and electrocaloric refrigeration simultaneously. The flexible PLZT 9/65/35 thick film presents a desirable breakdown field of 1998 kV/cm, accompanied by a superior recoverable energy density ( W rec ) of 40.2 J/cm 3 . Meanwhile, the thick film exhibits excellent stability of energy-storage performance, including a broad operating temperature (30–180 °C), reduplicative charge–discharge cycles (1 × 10 7 cycles), and mechanical bending cycles (2000 times). Moreover, a large reversible adiabatic temperature change (Δ T ) of 18.0 °C, accompanied by an excellent electrocaloric strength (Δ T /Δ E ) of 22.4 K cm/V and refrigerant capacity (RC) of 11.2 J/cm 3, is obtained at 80 °C in the flexible PLZT 9/65/35 thick film under the moderate applied electric field of 850 kV/cm. All of these results shed light on a flexible PLZT 9/65/35 thick film capacitor that opens up a route to practical applications in microenergy-storage systems and on-chip thermal refrigeration of advanced electronics.