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Manganese oxides/graphene is an electrode material currently under consideration for use in high-performance supercapacitors (SCs). The conventional, widely used wet chemical methods for preparing MnO2/graphene are tedious and consume large quantities of strong reduction/oxidation reagents. The resulting powder composites require adhesives to form a suitable electrode. In the present study, we report on a method for synthesizing MnO2/graphene composite electrodes using a second laser irradiation employing a laser of the polyether ether ketone. This simple and environmentally friendly method allows the patterning of electrodes together with the synthesis of the active materials. The MnO2/laser-induced graphene (LIG) electrode exhibited a high capacitance of 48.9 mF cm−2, which is about 2.4 times greater than a pure LIG electrode. Assembled all solid micro-supercapacitors (MSCs) containing the novel LIG electrodes delivered both high energy density (3.1 μWh cm−2) and power density (2.5 mW cm−2). These MSCs exhibited a capacitance retention of 94.3% over 3000 cycles, at a current density of 0.5 mA cm−2. The electrochemical performance was almost unaltered by bending the MSC to 150°. This method of synthesizing high-performance flexible electrodes is important for future development of wearable electronics. [ABSTRACT FROM AUTHOR]

Development of 3D hierarchically porous graphene (HPG) with supercapacitor performances at low cost has remained a challenge in electrochemical devices. Recently, laser engraving technology has been proposed as a promising and very useful method to inscribe self-designed electrode array directly onto polymeric substrates by instantaneously converting the starting material into few-layer graphene. Here we show HPG fabrication on commercial bakelite resulting in porous graphene embedded in polymer surface using the high repetition nanosecond fiber laser engraving under nitrogen atmosphere. The results showed that the as-prepared HPG presents a combination of interconnected macro-, meso- and micropores with a multi-modal pore size distribution. The morphologies, microstructures and their properties of HPG films can be governed by the laser processing parameters. Moreover, the HPG-based supercapacitors show outstanding electrochemical performance with specific capacitance superior to other supercapacitors reported previously. The simple, rapid and low-cost approach proposed in this work has great potential in large-scale applications of electronic and energy storage devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • 1. A novel general method for metal oxide nanoparticles (MONPs) modified laser-induced graphene (LIG) electrode. • 2. MONPs (M = Ti, Ni, Sn) with a diameter of 5–10 nm were synthesized by laser ablation in liquid. • 3. The preparation process of MONPs modified LIG electrodes are simple, low-cost and green. • 4. SnO 2 /LIG micro-supercapacitors display high area-specific capacitance (18.58 mF cm−2 at 10 mV s−1) and mechanical stability. Metal oxide nanoparticles (MONPs)-graphene composites are highly valued candidate electrode materials for electrochemical supercapacitor (SC). Here, we described the development of a versatile approach for fabricating SC electrodes by impregnating MONPs (M = Ti, Ni, Sn) synthesized by laser ablation in liquid on laser-induced graphene (LIG). A typical SnO 2 /LIG micro-supercapacitor (MSC) delivers an area-specific capacitance of 18.58 mF cm−2 at a scan rate of 10 mV s−1, which is 5.2 times greater than the unmodified LIG. Moreover, the MSC exhibits long-life cycling stability (retaining 82.15% of specific capacitance after 5000 cycles) and good mechanical flexibility (specific capacitance is reduced by 5% at bending angle of 150°). MONPs and LIG are prepared using the same laser processing system, and no chemical ligands or reducing agents used in the synthesis process, which is cost-effective and green. This simple and straightforward method provide a highly operable solution for the large-scale preparation of MSC. [ABSTRACT FROM AUTHOR]