cause degradation in organic and acidic electrolytes, [8,9] which limits long-term electrochemical stability. In addition, typical commercial paper exhibits poor tensile resistance and thus poor stability under prolonged mechanical deformations. [10][11][12] Therefore, improvements in both mechanical and chemical toughness must be made to develop reliable paperbased energy storage systems for flexible and wearable applications.Here, we consider mulberry paper (MP) as a potential substrate for fabrication of mechanically and chemically tough supercapacitors for flexible and wearable energy storage systems. Mulberry paper exhibits distinct characteristics that differentiate it from commercial paper that is conventionally made from conifer or broad leaf trees. First, the mulberry pulp is composed of 2-2.5 times longer fibers than commercial paper pulp [13][14][15][16] and forms a strong mechanical network [17,18] that retains its network structure even when wetted with electrolyte due to the strength of Van der Waals interactions and entanglement of fibers. [19][20][21] Second, mulberry pulp has high holocellulose composition, which contributes to the high mechanical toughness of mulberry paper. Last, the high holocellulose content makes mulberry paper hydrophilic making dip coating [19][20][21] of active material viable for scalable, easy fabrication. Although mulberry paper does not demonstrate stretchability due to strong network formation, it demonstrates high mechanical toughness that is suitable for flexible energy storage systems.Commercial paper is processed in weak acids, and small amount of acid typically remains after completion of the fabrication process that makes commercial paper susceptible to oxidation and acidolysis. [22,23] By contrast, mulberry paper is processed in a weak K 2 CO 3 solution (pH 9.0-10.0) making mulberry paper have a neutral pH (pH 6.0-7.0). [24][25][26] Therefore, mulberry paper is resistant to oxidation and acidolysis and, by extension, demonstrates high chemical toughness. Therefore, it is possible to use strong acid electrolytes that have high ionic conductivity to enhance electrochemical performance with stability under extreme conditions by making use of mulberry paper as a substrate. Despite these advantages compared to the Supercapacitors Paper energy storage systems have surfaced as a practical candidate for next-generation energy storage device [1][2][3] especially due to the ever-increasing importance on the development of sustainable, biodegradable, and efficient energy storage systems. Paper is lightweight, thin, and scalable, which makes it suitable for flexible and wearable energy storage systems that are capable of stable operation even under repeated bending and twisting. [4][5][6][7] However, one of the concerns with the use of a paper substrate is the poor chemical resistance that can