Abstract: Moist-electric generation (MEG) emerges as a new renewable energy technology, capable of harvesting electrical energy through the interaction of composite functional materials and ubiquitous moisture. Furthermore, with the advantages of being geographically unlimited and all-weather operation, MEG demonstrates great potential as an emergency energy source for powering low-power nodes in distributed sensor networks. To address the problems of low power and poor stability of current moisture-electric generators, this study designed a double-layer composite hydrogel (PGP) with Janus structure, based on polyacrylamide (PAM)/reduced graphene oxide (rGO)/lithium chloride (LiCl). The asymmetric structure was constructed by freeze polymerization to strengthen ion transport, enhancing energy output. The experimental results show that the PGP-based MEG (PMEG) can achieve a stable open-circuit voltage of 0.56 V and an ultra-high short-circuit density of 0.5 mA/cm² under the conditions of 80% RH and 30℃. This current density is more than tenfold the performance of most reported MEG. Furthermore, the PMEG exhibits unparalleled environmental adaptability and stability, maintaining a consistent voltage output of 0.5 V for over 500 hours. Through the series or parallel integration, an array composed of 8 PMEG units can output an open-circuit voltage of 4.2 V and a short-circuit current of up to 3.6 mA, which is sufficient to power small electronic devices. The asymmetric hydrogel design strategy proposed in this research provides new perspective and technological approach for efficiently harnessing moisture energy from the environment.