Surface Functionalization of TiO₂ Nanoparticles Influences the Conductivity of Ionic Liquid-Based Composite Electrolytes

Abstract

As one of the main components of ionic liquid-based composite electrolytes, nanoparticles play a major role in determining the performance of such electrolytes. In this study, four different TiO2-based nanoparticles are introduced into ionic liquid electrolytes to systematically investigate the influence of their conductivities and surface chemistries on the performance of composite electrolytes. Compared with conventional insulating nanoparticles, high-conductivity nanoparticles are free of blocking junctions, and the surface region of the nanoparticles can act as an additional pathway for ionic conduction. Meanwhile, the surface chemistry of the nanoparticle strongly determines the viscosity, network stability, and microscopic morphology of an ionic liquid-based composite electrolyte, thus affecting the ionic conductivity. Therefore, the highest conductivity of 4.29 mS cm–1 is achieved by the ionic liquid-based composite electrolyte with the SC-HC-TiO2 nanoparticle at a weight of 10 wt %, which has high conductivity and rich amino functional groups. DSCs using SC-HC-TiO2 show a high efficiency of 8.12% due to the simultaneous improvement of photocurrent density (J sc), open-circuit voltage (V oc), and fill factor (FF).

Gelation, Liquid Crystalline Behavior, and Ionic Conductivity of Nanocomposite Ionogel Electrolytes Based On Attapulgite Nanorods

“…Nowadays, the isotropic particles are the focal point in the design and synthesis of high performance ionogels, such as silica (SiO 2 ), − titanium dioxide (TiO 2 ), nanodiamonds, and zirconium dioxide (ZrO 2 ) . While for the ionogel electrolytes based on anisotropic nanoparticles, the existing literature has been focused mainly on carbon nanotubes (CNTs) and graphene oxide (GO) .…”

“…24,25 Particularly, further studies about the influence of intermolecular interactions, size, morphology, and external factors on the structure and properties of IL/nanoparticle composites has assisted the rational design of novel ionic conductive nanocomposite based on nanoparticles and ILs. 26 Nowadays, the isotropic particles are the focal point in the design and synthesis of high performance ionogels, such as silica (SiO 2 ), 29−31 titanium dioxide (TiO 2 ), 32 nanodiamonds, 33 and zirconium dioxide (ZrO 2 ). 34 While for the ionogel electrolytes based on anisotropic nanoparticles, the existing literature has been focused mainly on carbon nanotubes (CNTs) 35 and graphene oxide (GO).…”

Unveiling the Relationship between the Surface Chemistry of Nanoparticles and Ion Transport Properties of the Resulting Composite Electrolytes

“…The pristine fluorescent silica nanoparticle (f-SiO 2 ) is prepared by coating the CdSe quantum dots (QDs) with silica according to our previous work. 12 Subsequently, the fluorescent aminophenyl and amide group-functionalized silica nanoparticle (f-AP-SiO 2 and f-AM-SiO 2 , respectively) are synthesized following the corresponding silane coupling reactions as described in the Supporting Information. However, the strong acid could cause the severe surface oxidation and aggregation of quantum dots, resulting in the significant fluorescence quenching of them.…”

“…Nanoparticle composite electrolytes (NCEs) are ideal candidate materials to replace conventional liquid electrolytes for large-scale application of electrochemical devices, such as lithium-based batteries, − supercapacitors, , and dye-sensitized solar cells. − Room-temperature ionic liquids (ILs) have been widely investigated to prepare highly stable NCEs because of their exceptional physicochemical properties including nonflammability, low volatility, wide electrochemical window, and thermal stability. − Nanoparticles combined with ILs in NCEs not only immobilize ILs for use in solid devices but also provide attractive properties in energy devices. − In the presence of certain particles, the NCEs generally exhibit enhanced ionic conductivities and greater mechanical property than the ILs electrolytes. , This interesting effect has been explained by the concept of heterogeneous doping, in which the particles could absorb specific ions onto their oppositely charged surfaces, influencing both concentration and mobility of ion species in the composite systems. − …”

“…The FCLM technique is used to detect the topology of fluorescent nanoparticles in pure ILs, which directly gives the information of the particle network formed in the electrolytes. The pristine fluorescent silica nanoparticle (f-SiO 2 ) is prepared by coating the CdSe quantum dots (QDs) with silica according to our previous work . Subsequently, the fluorescent aminophenyl and amide group-functionalized silica nanoparticle (f-AP-SiO 2 and f-AM-SiO 2 , respectively) are synthesized following the corresponding silane coupling reactions as described in the Supporting Information.…”