A Few Case Studies on the Correlation of Particle Network and Its Stability on the Ionic Conductivity of Solid–Liquid Composite Electrolytes

Abstract

We discuss here the crucial role of the particle network and its stability on the long-range ion transport in solid-liquid composite electrolytes. The solid-liquid composite electrolytes chosen for the study here comprise nanometer sized silica (SiO2) particles having various surface chemical functionalities dispersed in nonaqueous lithium salt solutions, viz. lithium perchlorate (LiClO4) in two different polyethylene glycol based solvents. These systems constitute representative examples of an independent class of soft matter electrolytes known as "soggy sand" electrolytes, which have tremendous potential in diverse electrochemical devices. The oxide additive acts as a heterogeneous dopant creating free charge carriers and enhancing the local ion transport. For long-range transport, however, a stable spanning particle network is needed. Systematic experimental investigations here reveal that the spatial and time dependent characteristics of the particle network in the liquid solution are nontrivial. The network characteristics are predominantly determined by the chemical makeup of the electrolyte components and the chemical interactions between them. It is noteworthy that in this study the steady state macroscopic ionic conductivity and viscosity of the solid-liquid composite electrolyte are observed to be greatly determined by the additive oxide surface chemical functionality, solvent chemical composition, and solvent dielectric constant.

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

“…51 The existence of better particle networks leads to the presence of effective ion transport paths and facilitates ion transport, resulting in the enhancement of ion conductivity. 14 Compared with insulating particles, high-conductivity SC-HC-TiO 2 (HC-TiO 2 ) is free of blocking junctions, and the surface region of the particles can act as an extra pathway for ion conduction, improving ionic conductivity. It is speculated that the charge and ion transport in two different phases and across several solid/liquid interfaces in a high-conductivity system may involve electronic exchange-based ion transport.…”

“…In the composite electrolytes composed of SC-TiO 2 in the ionic liquid, NH 2 groups on SC-TiO 2 interact via hydrogen bonding either with ionic liquid molecules or with the NH 2 groups of adjacent oxide particles, resulting in the spanning attractive regularized particle networks . The existence of better particle networks leads to the presence of effective ion transport paths and facilitates ion transport, resulting in the enhancement of ion conductivity . Compared with insulating particles, high-conductivity SC-HC-TiO 2 (HC-TiO 2 ) is free of blocking junctions, and the surface region of the particles can act as an extra pathway for ion conduction, improving ionic conductivity.…”

“…Electrolyte is an important component of energy conversion and storage devices such as rechargeable lithium batteries, − supercapacitors, − and dye-sensitized solar cells (DSCs). , It should have high conductivity, good mechanical property, low flammability, etc. − Recently, research has been conducted on composite electrolytes, including solid–liquid composite electrolytes (“soggy sand” electrolytes), − composite polymer electrolytes (CPEs), , composite solid electrolytes (CSEs), etc. It has been demonstrated that composite electrolytes exhibit superior mechanical and synergistic electrical properties.…”

Polymer electrolyte developed from natural rubber‐polyacrylic acid co trimethoxysilyl propyl methacrylate grafted fumed silica and its application to dye sensitized solar cell

“…Then, the free counter ions are formed at the space charge region at the interfaces between oxide particles and liquid electrolytes. When the particles are close to each other or when they overlap, percolations in ionic conductivity are generated . However, the nanoparticles have high potential for aggregation that can obstruct the ion transportation on the TiO 2 in DSSCs electrodes because the two sub‐phases are separated .…”

Novel Composite Gel Electrolytes with Enhanced Electrical Conductivity and Thermal Stability Prepared Using Self-Assembled Nanofibrillar Networks

“…Several reports investigated the addition of inorganic fillers, such as silica (SiO 2 ), copper oxide (CuO), and titania (TiO 2 ) particles, into liquid or polymer electrolytes to enhance the conductivity and thermal stability. − Bhattacharyya et al found that the addition of specific amounts of oxide particles (SiO 2 and TiO 2 ) to organic solvent-based (liquid) electrolytes enhanced the conductivities of the composites relative to the pure liquid electrolytes. This phenomenon was explained using heterogeneous percolation theories at the interfaces .…”