Our team has developed a layer-by-layer hydrophilic membrane (LHM) as the “bendable water-enabled portable power banks”. It is bendable, cost-effective, lightweight, environmental-friendly,high-efficient. Moreover, it could achieve high-voltage (~0.8 V), high-current (~80 μA)long-lasting (4 hr) power output by dropping a few drops of DI water (or electrolyte solutions), which can be described as a "black technology" towards green clean energy.