Science Daily  July 4, 2023 Dielectric capacitors can become ideal, safe energy storage devices. However, they yield rather low energy densities compared with other energy storage devices such as batteries and supercapacitors. Researchers in Japan designed ultrahigh energy storage capacitors using two-dimensional (2D) high-κ dielectric perovskites (Ca2Nam–3NbmO3m+1; m = 3–6). Individual Ca2Nam–3NbmO3m+1 nanosheets exhibited an ultrahigh dielectric strength even in the monolayer form, which exceeded those of conventional dielectric materials. Multilayer stacked nanosheet capacitors exhibited ultrahigh energy densities, high efficiencies (>90%), excellent reliability (>107 cycles), and temperature stability (−50–300 °C); the maximum energy density was much higher than those of […]