Useful spontaneous hygroelectricity from ambient air by ionic wood

Spontaneous electricity generator using moisture in ambient air has been developed rapidly in recent years for its great potential in self-sustained systems. However, due to the lack of efficient and continuous ion transport, the power-generation ability and stability from existing materials are unsatisfactory (ultra-low current, intermittent voltage and strong dependence on moisture) for practical applications. Here we report a generator made of ionic wood processed from natural wood using a simple and effective strategy to form continuous nanostructures with LiCl salts like spider webs around the inner walls of wood microchannels (i.e., fiber lumina). A single generator spontaneously produced a sustainable voltage of around 750 mV with a useful current of around 712 μA in ambient environment. And it also exhibited outstanding stability even when ambient humidity suddenly decreased to below 10% and stayed for 10 h. Besides, a connected system consisting of only six components outputted a voltage up to 4.40 V and current up to 4.16 mA, which can power LED lights. Our ionic wood shows promise for ambient moisture-energy conversion to develop the next self-sustained power system, with low-cost, sustainability and easily larger-scale productions.