Rational Design of Nanostructured Electrode Materials toward Multifunctional Supercapacitors

Abstract

As an intermediate step during energy usage, supercapacitors with superior power density, long‐term cycling stability, and moderate energy density have attracted immense interest as a facile route to use energy in a clean, efficient, and versatile manner in smart grid applications, as well as portable devices and other applications. Currently, the major drawback of supercapacitors is the low energy density. Electrode materials are the key components determining the cell performance. Great research efforts are made to develop nanostructured electrode materials with high performance. On the other hand, integrating supercapacitors with other applications have led to the emergence of many new types of multifunctional supercapacitors, which are attractive for a myriad of applications. The current understanding on charge/discharge mechanisms of electric double layer capacitors and pseudo‐capacitors is discussed along with recent development in designing nanostructured electrode materials by structure/morphology engineering, doping, and crystal structure controlling. Achievements in multifunctional supercapacitors like flexible supercapacitors, all‐solid‐state supercapacitors, self‐healing supercapacitors, electrochromic supercapacitors, self‐chargeable supercapacitors, and supercapacitors integrated with sensors are illustrated. Finally, opportunities and challenges in developing high performance and multifunctional supercapacitors are proposed.

Chemical Modifications of Layered Double Hydroxides in the Supercapacitor

“…Some similar results are found in monometallic Co 2+ Co 3+ -CO 3 LDHs and Ni 2+ /Ni 3+ LDH electrode materials [45,46] ; thus, the ratio of mono-active metal ions can affect the electrochemical performance. Some other LDH materials (i.e., NiCo-LDH, NiFe-LDH, NiMn-LDH, CoMn-LDH, CoFe-LDH) [12,42,48,49,50] have also been explored for pseudo-supercapacitor application, because the synergistic effect between different metals can promote electrochemical performance. In recent years, there have been some reports that the ratio of Co/Ni can regulate the morphology of the LDH materials.…”

Fabrication of Oxygen‐Vacancy Abundant NiMn‐Layered Double Hydroxides for Ultrahigh Capacity Supercapacitors

“…Compared to conventional energy storage devices, SCs have higher specific capacity, faster charging and discharging time, longer cycle life, and excellent thermal stability. Such properties further underlined SCs great potential as an emerging type of electrochemical energy storage (EES) system for world's most advanced adjustable EES device, nanostructured electrode, self‐charging power textiles, flexible printed circuits, etc. As to the electrode material, a high‐performance SC electrode generally requires high electrical conductivity, large ion‐accessible surface area, fast ionic transport rate, and good electrochemical stability .…”

Carbon Transition‐metal Oxide Electrodes: Understanding the Role of Surface Engineering for High Energy Density Supercapacitors

“…[26] However, in-depth investigation about the construction of strongly coupled C-TMO hybrids with intimate interfacial contact is limited even though such factor may play a crucial role in the charge transfer process. Although substantial numbers of review articles are present on the development of supercapacitor, [5,[27][28][29][30][31][32][33][34] the present minireview focuses on recent development in the preparation of C-TMO hybrid material as efficient electrode towards high energy density SCs, which has not received due attention. Importantly, this report analyzes carbon materials as active support, core element, and conductive substrate in order to understand the specific roles of carbon and TMO.…”