Passive fuel cells, using diffusion and natural convection for fuel delivery, are regarded as promising candidates for powering portable devices including mobile phones and laptops. However, the performance of passive fuel cells which employ typical liquid alcohol fuels are still limited, which thereby greatly hampered their commercialization progress. Recently, a novel concept named the electrically rechargeable liquid fuel (e-fuel), with its rechargeability, cost-effectiveness, and superior reactivity, has attracted increasing attention. In this study, a passive fuel cell using the liquid e-fuel and the ambient air for electricity production is designed and fabricated. This passive fuel cell is demonstrated to achieve a peak power density of 116.2 mW cm −2 along with a stable operation for over 350 h, exhibiting great prospect for future applications.

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The liquid fuel cell, with its high energy density and ease of fuel handling, has attracted great attention worldwide. However, its real application is still being greatly hindered by its limited power density. Hence, the recently proposed and demonstrated fuel cell, using an electrically rechargeable liquid fuel (e-fuel), is believed to be a candidate with great potential due to its significant performance advancement. Unlike the conventional alcoholic liquid fuels, the e-fuel possesses excellent reactivity, even on carbon-based materials, which therefore allows the e-fuel cell to achieve superior performance without any noble metal catalysts. However, it is found that, during the cell operation, the water generated at the cathode following the oxygen reduction reaction could lead to a water flooding problem and further limit the cell performance. To address this issue, in this work, by manipulating the cathode composition, a blended binder cathode using both Nafion and polytetrafluoroethylene as binding agents is fabricated and demonstrated its superiority in the fuel cell to achieve an enhanced water management and cell performance. Furthermore, using the developed cathode, a fuel cell stack is designed and fabricated to power a 3D-printed toy car, presenting this system as a promising device feasible for future study and real applications.