Nanosheet technology developed to boost energy storage dielectric capacitors

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 […]

Researchers fabricate novel flexible supercapacitors on paper

Nanowerk  March 6, 2023 Paper’s inherent characteristics can be exploited to overcome the limitations of conventional substrates, such as weak adhesion and large mass densities. Researchers in South Korea proposed a method for fabricating vertically integrated multi-electrodes within only a single sheet of paper. Despite the randomly distributed fibrous networks in paper, the multi-layered electrodes were uniformly formed and completely separated by applying a removable hydrophobic wax barrier confinement inside a single sheet of paper. Conventional two-dimensional planes can be used as three-dimensional scaffolds. The highly integrated electrodes and circuit systems were located within a sheet of paper, making a […]

Uncovering the key to safer energy storage devices that avoid thermal runaway

Phys.org  May 9, 2022 Researchers in South Korea investigated the thermal properties of electric double-layer capacitors (EDLCs) for a technical foundation in thermal measurement and revealed significant information. The reversible entropy and free energy changes in the EDLCs caused dynamic changes in the effective heat capacity of the electrodes, which were monitored in real-time during charge and discharge operations. In an EDLC with a 6 M KOH electrolyte, the effective heat capacities of the positive and negative electrodes with a varying voltage from 0 to 1 V were estimated to decrease by approximately 9.14% and 3.91%, respectively. This polarization dependence […]

The hidden behavior of supercapacitor materials

Phys.org  November 9, 2021 Polyaniline (PANI) is conductive and can be used as the electrode in a supercapacitor device, storing charge by trapping ions. To maximize energy storage, an international team of researchers (UK, Brazil) developed a novel method of depositing a thin layer of PANI onto a forest of conductive carbon nanotubes. This composite material makes an excellent supercapacitive electrode. However, as the composite is made up of different materials, it is difficult to separate and fully understand the complex processes which occur during charging and discharging. The researchers used Distribution of Relaxation Times analysis technique to examine complex […]

Novel approach improves graphene-based supercapacitors

EurekAlert  August 3, 2020 Researchers in Australia have developed a technique to improve the performance of quasi‐solid‐state supercapacitors made by graphitized silicon carbide on silicon electrodes and polyvinyl alcohol (PVA)+H2SO4 gel electrolyte. They increased the specific capacitance of the cell up to 3‐fold resulting from a simple agent‐free, in situ, electrochemical treatment leading to functionalization of the graphitic electrodes. The functionalization of the electrodes simultaneously enables redox reactions, without adding any redox agent, and increases the overall capacitance…read more. TECHNICAL ARTICLE

Supercapacitor promises storage, high power and fast charging

Science Daily  May 5, 2020 The overall electrochemical performance of the semiconductor heterostructures often depends on the carrier mobility from the semiconductor interfaces and faradaic redox reactions from their active sites. An international team of researchers (Pennsylvania State University, China) has developed low-cost, two-step method to controllably grow MnO2 nanorods directly on CoMn2O4 nanosheets with robust adhesion. An induced electric field resulted from the interface effect of heterostructures tailors the kinetic performance of electrons and ions during the charge-discharge process, enhancing the electron mobility and reducing diffusion barrier for charge carriers (OH−) ions migration. As a result, the rational design […]

Newly devised static negative capacitor could improve computing

Science Daily  April 8, 2019 Previously proposed designs for negative capacitors worked on a temporary, transient basis. An international team of researchers (France, Russia, USA Argonne National Laboratory) created a permanent static negative capacitor which works as a steady-state, reversible device. The prime component of the negative capacitor involves a filling made of a ferroelectric material. By splitting a nanoparticle into two equal ferroelectric domains of opposite polarization, separated by a boundary called a domain wall, they were able to minimize the effect of the total depolarizing electric field. They showed that the ferroelectric nanodot capacitor hosts a stable two-domain […]

3D-Printed Graphene Scaffold Breaks Capacitor Records

Inside Science  October 18, 2018 A team of researchers in the US (UC Santa Cruz, Lawrence Livermore National Laboratory) has made a 3D printed graphene aerogel electrode with MnO2 loading of 182.2 mg cm−2, which achieves a record-high areal capacitance of 44.13 F cm−2. the electrode can simultaneously achieve excellent capacitance normalized to area, gravimetry, and volume, which is the trade-off for most electrodes. The work successfully validates the feasibility of printing practical pseudocapacitive electrodes, which might revolutionize pseudocapacitor fabrication… read more. TECHNICAL ARTICLE