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Hybrid supercapacitors have been regarded as next-generation energy storage devices due to their outstanding performances. However, hybrid supercapacitors remain a great challenge to enhance the energy density of hybrid supercapacitors. Herein, a novel approach for high-energy density hybrid supercapacitors based on a laser scribed graphene cathode and AlPO4-carbon hybrid coated H2Ti12O25 (LSG/H-HTO) was designed. Benefiting from high-energy laser scribed graphene and high-power H-HTO, it was demonstrated that LSG/H-HTO delivers superior energy and power densities with excellent cyclability. Compared to previous reports on other hybrid supercapacitors, LSG/H-HTO electrode composition shows extraordinary energy densities of ~70.8 Wh/kg and power densities of ~5191.9 W/kg. Therefore, LSG/H-HTO can be regarded as a promising milestone in hybrid supercapacitors.

Hybrid supercapacitors have recently emerged as next-generation energy storage devices that bridge the gap between supercapacitors and lithium-ion batteries. However, developing high energy cathodes that maintain longterm cycle stability and a high rate capability for real applications remains a significantly challenging issue. Herein, we report a facile synthesis method for a laser-scribed graphene/LiNi 1/3 Mn 1/3 Co 1/3 O 2 (LSG/NMC) composite for high energy cathode materials for use in hybrid supercapacitors. LSG/NMC composites exhibit not only a high capacitance of up to 141.5 F/g but also an excellent capacitance retention of 98.1% after 1000 cycles at a high current density of 5.0 A/g. The introduction of an NMC spacer between the LSG layers provides an enlarged interspace that can act as an efficient channel for additional storage sites and rapid access. In addition, we further confirmed that hybrid supercapacitors using LSG/NMC cathodes and H 2 T 12 O 25 anodes with an AlPO 4 /carbon hybrid coating layer (H-HTO) deliver a remarkable energy density of~123.5 Wh/kg, power density of~14074.8 W/kg, and a long-term cycle stability of 94.6% after 20,000 cycles. This work demonstrates that our proposed material can be considered a strong cathode candidate for next-generation hybrid supercapacitors.

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-Multilayer capacitors with high ripple current and high capacitance were manufactured.The electrical properties of these capacitors were characterized for potential application for DC-link capacitors in hybrid electric vehicle inverters. Internal electrode structures were designed to achieve high capacitance and reliability. A single multilayer capacitor showed 0.46 µF/cm 3 of capacitance, 0.65% of dielectric loss, and 1450 V to 1650 V of dielectric breakdown voltage depending on the design of the internal electrode. The capacitor module designed with several multilayer capacitors gave a total capacitance of 450 µF, which is enough for hybrid electric vehicles. In particular, an equivalent series resistance of 4.5 mΩ or less will result in 60 A rms , thereby reaching the allowed ripple current for hybrid electric vehicles.