For passive operation you can utilize a standard RECHARGABLE battery like these:
BK-80AAAB9B Panasonic - BSG Nickel-Metall-Hybrid (NiMH) 1.2V 750mAh AAA
N-700AACT Panasonic - BSG NICAD (Nickel-Cadmium) 1.2V 700mAh AA
B73180A0101M199 EPCOS - TDK Electronics Lithium-Ceramic with 1.5V 100µAh of the new [CeraCharge™](Elektronische Komponenten und Teilesuche | DigiKey Electronics 75855&stock=1&rohs=1&nstock=1&datasheet=1&photo=1) series
It depends on your use case and other requirements like runtime or RoHS/REACH.
Normally the energy transmitted and received by the Wireless Charging Coil could be enough to wake up a Low-Power MCU and check the I/O’s what reaction is necessary.
See the below blog for more details: