High-pressure environments require that power supplies of electronic devices can withstand high pressure without a hard shell. While compact reduced graphene oxide (rGO) electrodes enhance pressure tolerance, they suffer from compromised capacitance and power output due to the decreased ion-accessible surface area and blocked or collapsed ion channels. To overcome this challenge, carbon quantum dots (CQDs) were uniformly embedded into rGO film to create a compact yet porous electrode. This was achieved via a hydrothermal reaction to form a rGO/CQDs hydrosol by bonding CQDs to rGO nanosheets, followed by a subsequent vacuum filtering. The “spacer” function of CQDs improves the ion-accessible surface area, ion migration, and compressive strength of the rGO/CQDs films. Molecular dynamics simulations further confirm that embedded CQDs enhance both Young's modulus and the diffusion coefficient of hydronium ions within the rGO/CQDs films. Thus, at an ultra-high pressure of 360 MPa, the prepared rGO/CQDs films retained an impressive 81.2% of their initial capacitance (219.7 F cm⁻³ at 0.8 mA cm⁻²). The rGO/CQDs-based supercapacitors retained a high volumetric power density of 59.4 W cm⁻³ at 180 MPa. These findings demonstrate the great potential of rGO/CQDs films for pressure-tolerant power supply devices.

This work provides a comprehensive review of the utilization of the Finite Element Analysis (FEA) in optimizing current density distribution within the Electrical Contact Interfaces (ECIs) of Electromagnetic Railguns (EMRs). Mastery over the current density distribution at ECIs is crucial for boosting the operational efficiency and longevity of EMRs. FEA is instrumental in identifying and rectifying issues stemming from non-uniform current density distributions, which can result in severe problems like local overheating, material degradation, increased friction wear, and a decline in launch capabilities. This review delineates the pivotal factors affecting current density at ECIs, including the Velocity Skin Effect (VSE), Current Skin Effect (CSE), Proximity Effect (PE), input current, contact pressure, and contact resistance. It then explores recent advancements on the FEA-driven optimizations of material and structures, which have markedly enhanced performance of EMRs. Challenges in applying FEA—such as the complexity of modeling multi-field interactions, computational demands, and ensuring simulation reliability—are also addressed, with recent innovations offering promising solutions. This work concludes by underlining the indispensable contribution of FEA to the progressive development of EMRs, spotlighting its vital role in spearheading future innovations through the fusion of cutting-edge methodologies and interdisciplinary collaborations.