The article presents a systematic framework to evaluate and improve the energy efficiency of mobile soft robots.

Utilizing supercapacitors to convert low-grade heat into electrical energy for storage is an efficient waste heat recovery technology. In this study, the graphene films with a hierarchical porous structure are prepared, and a thermal charging supercapacitor is designed using RGO films as the electrode material. Under the influence of varying temperature fields, a different potential is induced on the working electrode and reference electrode surface of the supercapacitor, resulting in a potential difference U _out between them. The balanced voltage U _s of the supercapacitor increases linearly with the increase of the temperature difference ΔT and grows with the rise in solution concentration. The thermoelectric coefficient of the supercapacitor with 0.1 M KCl solution can reach 1.46 mV/°C. The thermoelectric coefficient increases with the height of the RGO film, the area of the RGO film, and the concentration of KCl solution. Discharge tests reveal that the capacitance of the supercapacitor is less affected by temperature difference, but significantly influenced by components constituting the supercapacitor (such as the concentration of the electrolyte solution). Furthermore, increasing the temperature and the concentration of the solution can effectively reduce the internal resistance of the supercapacitor.

The conversion of low-grade heat into storable electrical energy using nanoporous carbon materials represents an efficient energy harvesting strategy. In this study, a reduced graphene oxide (RGO) and carbon nanotube (CNT) composite with a rich microporous structure was synthesized. A symmetrical thermoelectric cell was constructed to harvest thermal energy. The application of a temperature difference (ΔT) generated a stable equilibrium voltage (U_s), which scaled linearly with ΔT. The resulting thermoelectric coefficient (U_s/ΔT) increased markedly with the carbon nanotube (CNT) content, underscoring the effectiveness of CNT incorporation for improving thermoelectric properties. It also shows a non-monotonic dependence on KCl concentration, first increasing and then decreasing, with a maximum value of 4.17 mV/°C achieved in 0.1 M KCl using the RGO-5%CNTs electrode. When connected to an external load, the discharge voltage and current decay rapidly before stabilizing within seconds. Circuit analysis reveals that the incorporation of CNTs reduces internal resistance and increases the equivalent capacitance. Although instantaneous discharge power declines quickly, the addition of CNTs elevates its initial value and slows the decay rate. Both the average output power and thermoelectric conversion efficiency improve with increasing ΔT and are further enhanced at higher CNT content. Overall, the RGO-CNT composite demonstrates significantly superior thermoelectric performance compared to pure RGO.

This study aims to investigate the effect of the ring plate on the mechanical performance of X‐type tube‐gusset joints. The failure modes, ultimate strengths, and failure mechanisms of X‐joints with ring plates were investigated through experiments and finite element analyses. The results indicated that the ring plate and the chord within the effective range of the ring plate constituted the primary bearing structure of the X‐joint. Increases in the ring plate thickness and width increased the ultimate strength of the X‐joint. By considering the forces of the braces as a superposition of the bending moment and the force acting on the gusset of the X‐joint, a simplified calculation method for the ultimate strength of X‐joints was established. The derivation process was validated and refined through experiments and finite element analyses. Finally, a safe and reliable formula was derived for evaluating the ultimate strength of X‐joints.