Biosynthesis of Spatially Differentiated Cellulose for Flexible All-in-one Supercapacitors.

Bacterial cellulose (BC) is a sustainable scaffold for flexible energy-storage devices, but conventional biosynthesis provides limited control over through-thickness structure, making it difficult to integrate distinct functional regions within a monolithic structure. Here, we use oxygen-guided biosynthesis to grow spatially differentiated BC scaffolds (SDBC) for flexible all-in-one supercapacitors. By creating air-water and water-oil oxygen-accessible interfaces, the microbes' aerobic nature directs cellulose deposition into two dense biofilms connected by an open fibrillar interlayer in a single cultivation step. The dense surface region supports polyaniline loading and charge storage, while the interlayer accommodates the gel electrolyte and facilitates ion transport. The resulting supercapacitor combines structural continuity with deformation tolerance, achieving high ionic conductivity (112.0 mS cm-1), mechanical toughness (1.77 MJ m-3), areal capacitance (410.6 mF cm-2), and energy density (34.0 µWh cm-2). This work establishes a bottom-up route to introduce spatial differentiation and structural continuity during cellulose biosynthesis and provides a platform for monolithic soft energy-storage devices.