Synthesis of P‐Doped and NiCo‐Hybridized Graphene‐Based Fibers for Flexible Asymmetrical Solid‐State Micro‐Energy Storage Device

Abstract

subsequently increasing demand for lightweight and highly flexible power modules is essentially one of the critical challenges for the progress of miniaturized portable and wearable electronics. [1] 1D fiber supercapacitor, as a promising candidate among various electrode materials, has been intensively investigated. The fiber supercapacitors (FSCs) can be easily integrated into extremely small devices with tiny sizes and various kinds of shapes due to their small volume and high flexibility. [2] Consequently, the construction of solidstate flexible energy storage systems is of great significance for the new generation of electronic devices.Graphene-based fiber supercapacitor has been widely applied in engineering field because of its superior electrical conductivity and large specific surface area for the past few years. [3] However, the 2D structure makes graphene sheets tending to aggregate during the preparation process. [4] Therefore, one way to solve this problem is to use carbon fibers as substrates. Apart from the high flexibility, the carbon fiber substrate possesses high surface area and desirable electrochemical stability. The doping of heteroatom could significantly improve electrochemical performance of graphene-based fiber supercapacitors. Specifically, the heteroatoms such as nitrogen (N), boron (B), sulfur (S), phosphorus (P) substituting some atoms in carbon nanomaterials is an effective way to tailor their electron-donor properties, [5] then to further improve their conductivity and electrochemical performances. In general, P-doped nanofibers were successfully prepared by impregnating H 3 PO 4 , (NH 4 ) 3 PO 4 , and triphenylphosphine (TPP) into the carbon materials, respectively, followed by carbonization. [6] In order to achieve a better application in an industrial production, an easy-handling fabrication process, with a lower reaction temperature and using attractive source of phosphorus, has become a key challenge for graphene-based fiber supercapacitors.Carbon materials, known as the most common class of electric double-layer materials, can deliver long cycling life, but their specific capacitance is limited, especially used as negative electrode in alkaline electrolyte. The pseudocapacitor materials such as conductive polymers and metal oxides can show high Fiber supercapacitors (FSCs) are promising energy storage devices in portable and wearable smart electronics. Currently, a major challenge for FSCs is simultaneously achieving high volumetric energy and power densities. Herein, the microscale fiber electrode is designed by using carbon fibers as substrates and capillary channels as microreactors to space-confined hydrothermal assembling. As P-doped graphene oxide/carbon fiber (PGO/CF) and NiCo 2 O 4based graphene oxide/carbon fiber (NCGO/CF) electrodes are successfully prepared, their unique hybrid structures exhibit a satisfactory electrochemical performance. An all-solid-state PGO/CF//NCGO/CF flexible asymmetric fiber supercapacitor (AFSC) based on the PGO/CF as the negative e...

True Meaning of Pseudocapacitors and Their Performance Metrics: Asymmetric versus Hybrid Supercapacitors

“…On the other hand, improved electrochemical performance induced by foreign carbonaceous materials has also been reported. [ 209 ] For instance, NiCo 2 O 4 ‐based graphene oxide/carbon fiber (NCGO/CF) electrodes were prepared and paired with a P‐doped graphene oxide/carbon fiber (PGO/CF) negative electrode. The resulting fiber‐type HSSC delivered a high energy density of 36.77 mWh cm −3 at a power density of 142.5 mW cm −3 , and their unique hybrid structures exhibit satisfactory electrochemical performance.…”

Heteroatom‐Doped and Oxygen‐Functionalized Nanocarbons for High‐Performance Supercapacitors

“…[175] Noting the enhanced gravimetric capacitance of 315.2 F g −1 at 0.42 A g −1 in 6 m KOH (3E), it is important to summarize that P-doping in graphene structures leads to i) distortion of graphene wrinkles due to longer PC bond than CC bond which results in the higher surface area, increased inter-layer spacing of GO (≈3.63 Å compared to pristine GO of 3.55 Å), ii) improved electrical conductivity, and iii) induced topological defects. [176] All these changes can be regarded as intentional atomic-scale modifications, and explored to further improve the energy storage performance. Experimental data supporting the positive influence of P-doping on the chargestorage performance of nanocarbon are also reported.…”

“…[166,175] In fact, P-doped GO/carbon fiber is operated in a potential range of −1.2 to 0 V in 6 m KOH versus Hg/ HgO. [176] The stable voltage for the symmetric device of rGO, P-doped rGO, and passivated P-doped rGO in 6 m KOH are 1, 1.3, and 1.4 V, respectively. [166] This observation is also important for rational design of doped nanocarbons to obtain the best charge storage performance.…”

Mass Production of Nanowire-Nylon Flexible Transparent Smart Windows for PM2.5 Capture

“…For example, commercial sponge was selected to combine with nanomaterials for oil spill remediation (Ge et al., 2014). In addition, carbon cloth (Liu et al., 2012) and graphene-based fibers (Zhou et al., 2018) were always used as electrodes for batteries and supercapacitors. That is, NW-nylon meshes are transparent, flexible, and porous; have strong affinity to air pollutants; and therefore show high removal efficiency at low pressure drop (Jeong et al., 2017).…”