Na⁺-preintercalated α-MnO₂ for printed electrodes of aqueous hybrid supercapacitors

The surging demand for adaptable energy storage systems has catalyzed the advancement of high-performance supercapacitors specifically engineered for wearable and flexible electronics. Nevertheless, conventional electrode materials, such as MnO₂, are inherently constrained by poor electrical conductivity, limited specific surface area, and a scarcity of electrochemically active sites. In this work, we report a Na⁺ pre-intercalated α-MnO₂ (Na_0.93Mn₈O₁₆) as a high-performance electrode material for aqueous hybrid supercapacitors, addressing the intrinsic electronic and ionic transport limitations of pristine MnO₂. Density functional theory calculations elucidate that Na⁺ pre-intercalation substantially enhances electronic conductivity, modulates hierarchical porosity, and strengthens ion adsorption within the MnO₂ framework. The optimized Na_0.93Mn₈O₁₆ electrode delivers a specific capacitance of 277.46 F g⁻¹ at 0.5 mV s⁻¹, maintaining 79.53% of its initial capacitance after 25,000 charge/discharge cycles. Furthermore, flexible supercapacitors fabricated via inkjet printing exhibit outstanding mechanical resilience under repeated deformation. The integrated devices are capable of powering light-emitting diode arrays, underscoring their practical applicability for next-generation deformable electronics. This study establishes a synergistic strategy that couples ion pre-intercalation with scalable fabrication, offering a versatile design paradigm for the development of high-performance flexible energy storage technologies.