Superstable osmotic energy conversion based on strong cellulose membrane

In recent years, the reverse electrodialysis system (RED) has attracted significant attention because of its sustainable and pollution-free characteristics. Ion-selective membranes function as a core component for RED to directly convert salinity gradient energy into electric power. However, traditional membranes composed of 2D inorganic and organic materials currently require complex preparation technologies, high cost, or consume petrochemical resources and lead to environmental issues. In this study, we developed a sustainable, large-scale, ultra-thin (∼30 µm), and mechanical strong (>89 MPa) cellulose membrane via a phase inversion strategy of positively charged cellulose (namely PPC membrane). By coupling sufficiently positive groups and nanoscale pores, our PPC membrane demonstrates a power density of 2.2 W/m2 under 0.01/0.5 M salinity gradient and a low internal resistance ∼11 kΩ. More importantly, the prepared PPC membrane shows high structural integrity even enduring 300-day water soaking with various pH of 3–12, which indicates its long-term stable power output in harsh conditions. The PCC membrane exhibits great potential for advanced ion-sieving applications.