Examining paper-based laser-induced graphene and its δ-MnO2 nanocomposite for flexible solid-state supercapacitors: Towards the powering of sustainable and disposable electronics

Paper-based laser-induced graphene (paper-LIG) was employed as a sustainable and low-cost electrode for the development of flexible all-solid-state micro-supercapacitors (MSCs). The CO 2 laser scribing generates a porous, conductive 3D multilayered graphene network directly on cellulose paper substrates, eliminating the need for inks, transfer steps or binders. When assembled with a PVA:LiClO 4 gel polymer electrolyte in symmetric configuration, paper-LIG electrodes delivered a capacitance of ∼2.0 mF/cm 2 at 18.5 μA/cm 2 , governed primarily by electric double-layer charge storage. To improve energy density, a conformal pseudocapacitive coating of δ-MnO 2 nanostructures was electrodeposited onto the LIG scaffold. This composite MSC exhibited an increased capacitance of ∼50 mF/cm 2 , corresponding to an energy density of 6 μWh/cm 2 , while maintaining a maximum power above 0.1 mW/cm 2 . Electrochemical impedance spectroscopy and temperature-dependent measurements confirmed that ionic transport within the polymer electrolyte rather than electrode kinetics, is the dominant factor limiting device performance. This detailed and systematic comparison between carbon-based and pseudocapacitive paper-LIG architectures highlights both the promise of δ-MnO 2 -functionalized LIG for boosting energy density, the mechanisms beyond its cycling aging and the critical role of electrolyte in the MSCs performance. These findings provide design guidelines for scalable, disposable energy storage solutions compatible with emerging flexible and wearable electronic platforms. • Laser-induced graphene directly formed on cellulose paper enables binder-free MSCs. • δ-MnO 2 -coated LIG MSCs delivers 50 mF/cm 2 - 20x higher than LIG - and 6 μWh/cm 2 . • EIS and temperature analysis identify electrolyte transport as performance limiter. • Cycling fading traced to irreversible Mn 4+ .→Mn 3+ reduction and loss of pseudocapacitance • Sustainable paper-based MSCs demonstrated for flexible and disposable electronics.