Improvements to the Overpotential of All-Solid-State Lithium-Ion Batteries during the Past Ten Years

After the research that shows that Li10GeP2S12 (LGPS)-type sulfide solid electrolytes can reach the high ionic conductivity at the room temperature, sulfide solid electrolytes have been intensively developed with regard to ionic conductivity and mechanical properties. As a result, an increasing volume of research has been conducted to employ all-solid-state lithium batteries in electric automobiles within the next five years. To achieve this goal, it is important to review the research over the past decade, and understand the requirements for future research necessary to realize the practical applications of all-solid-state lithium batteries. To date, research on all-solid-state lithium batteries has focused on achieving overpotential properties similar to those of conventional liquid-lithium-ion batteries by increasing the ionic conductivity of the solid electrolytes. However, the increase in the ionic conductivity should be accompanied by improvements of the electronic conductivity within the electrode to enable practical applications. This essay provides a critical overview of the recent progress and future research directions of the all-solid-state lithium batteries for practical applications

Application of Organic Solid Electrolytes

If ions are considered to be solid material which transport electric charges, polymer materials can then be considered as organic solid electrolytes. The role of these electrolytes is discussed for (1) ion concentration sensors; (2) batteries using lithium as the cathode and a charge complex of organic material and iodine in the anode; and (3) elements applying electrical double layer capability

Ceria-based materials for high-temperature electrochemistry applications

This paper describes the experimental studies of multi-component solid state electrolytes based on CeO2 and their application in intermediate temperature electrochemical devices. Two important aspects are emphasized: the effect of different dopants’ ionic radius and concentration on the electrical properties of CeO2-based solid solutions in air and the influence of combined dopants on the electrolytic properties of solid electrolytes from the standpoint of the critical oxygen partial pressure pO2 at which point the values of the electronic and ionic components of conductivity are equal. Examples of usage of the developed multi-component Ce0.8(Sm0.75Sr0.2Ba0.05)0.2O2-δ electrolyte synthesized by solid state, laser evaporation and combustion methods and composites on the base of Ce0.8(Sm0.8Sr0.2)0.2O2−d electrolyte as a component of electrochemical devices such as solid oxide fuel cell, gas sensors and as a component of the mixed ionic and electronic conducting (MIEC) membranes for hydrogen and syngas gas production are cited.The present work was financially supported by Russian Foundation for Basic Research and Government of Sverdlovsk region, grant no. 13-03-96098

Response behaviour of oxygen sensing solid electrolytes

The response time (t r) after a step change in oxygen partial pressure was investigated for some solid electrolytes used in Nernst type oxygen sensors. The electrolyte as well as the (porous) electrode material affect the value oft r. Stabilized Bi2O3 materials exhibit slower response rates (largert r values) than stabilized ZrO2. Introduction of Bi2O3 in stabilized ZrO2 increases the response time. Gold electrodes show a higher response rate than platinum in the oxygen partial pressure and temperature region used.\u

Fast microwave-assisted synthesis of Li-stuffed garnets and insights into Li diffusion from muon spin spectroscopy

Lithium-stuffed garnets attract huge attention due to their outstanding potential as solid-state electrolytes for lithium batteries. However, there exists a persistent challenge in the reliable synthesis of these complex functional oxides together with a lack of complete understanding of the lithium-ion diffusion mechanisms in these important materials. Addressing these issues is critical to realizing the application of garnet materials as electrolytes in all solid-state lithium-ion batteries. In this work, a cubic phase garnet of nominal composition Li6.5Al0.25La2.92Zr2O12 is synthesized through a microwave-assisted solid-state route for the first time, reducing considerably the reaction times and heating temperatures. Lithium-ion diffusion behavior is investigated by electrochemical impedance spectroscopy (EIS) and state-of-art muon spin relaxation (μSR) spectroscopy, displaying activation energies of 0.55 ± 0.03 eV and 0.19 ± 0.01 eV respectively. This difference arises from the high inter-grain resistance, which contributes to the total resistance in EIS measurements. In contrast, μSR acts as a local probe providing insights on the order of the lattice, giving an estimated value of 4.62 × 10−11 cm2 s−1 for the lithium diffusion coefficient. These results demonstrate the potential of this lithium-stuffed garnet as a solid-state electrolyte for all-solid state lithium-ion batteries, an area of growing interest in the energy storage community

Solid state lithiation-delithiation of sulphur in sub-nano confinement: a new concept for designing lithium-sulphur batteries.

We investigate the detailed effects and mechanisms of sub-nano confinement on lithium-sulfur (Li-S) electrochemical reactions in both ether-based and carbonate-based electrolytes. Our results demonstrate a clear correlation between the size of sulfur confinement and the resulting Li-S electrochemical mechanisms. In particular, when sulfur is confined within sub-nano pores, we observe identical lithium-sulfur electrochemical behavior, which is distinctly different from conventional Li-S reactions, in both ether and carbonate electrolytes. Taken together, our results highlight the critical importance of sub-nano confinement effects on controlling solid-state reactions in Li-S electrochemical systems

Influence of electrode geometry and NLLS fit analysis of I-V measurements in a three-electrode cell

The analysis of electrode polarisation (I-V) measurements of oxygen electrodes on δ-Bi2O3-based solid electrolytes is complicated by an ohmic polarisation correction which is of the order of the electrode resistance. The analysis can be performed with a NLLS fit technique, which includes this correction resistance, Ru, as adjustable parameter. By an appropriate choice of the electrode geometry the factor Ru can be minimized

Scalable Freeze-Tape-Casting Fabrication and Pore Structure Analysis of 3D LLZO Solid-State Electrolytes.

Nonflammable solid-state electrolytes can potentially address the reliability and energy density limitations of lithium-ion batteries. Garnet-structured oxides such as Li7La3Zr2O12 (LLZO) are some of the most promising candidates for solid-state devices. Here, three-dimensional (3D) solid-state LLZO frameworks with low tortuosity pore channels are proposed as scaffolds, into which active materials and other components can be infiltrated to make composite electrodes for solid-state batteries. To make the scaffolds, we employed aqueous freeze tape casting (FTC), a scalable and environmentally friendly method to produce porous LLZO structures. Using synchrotron radiation hard X-ray microcomputed tomography, we confirmed that LLZO films with porosities of up to 75% were successfully fabricated from slurries with a relatively wide concentration range. The acicular pore size and shape at different depths of scaffolds were quantified by fitting the pore shapes with ellipses, determining the long and short axes and their ratios, and investigating the equivalent diameter distribution. The results show that relatively homogeneous pore sizes and shapes were sustained over a long range along the thickness of the scaffold. Additionally, these pores had low tortuosity and the wall thickness distributions were found to be highly homogeneous. These are desirable characteristics for 3D solid electrolytes for composite electrodes, in terms of both the ease of active material infiltration and also minimization of Li diffusion distances in electrodes. The advantages of the FTC scaffolds are demonstrated by the improved conductivity of LLZO scaffolds infiltrated with poly(ethylene oxide)/lithium bis(trifluoromethanesulfonyl)imide (PEO/LITFSI) compared to those of PEO/LiTFSI films alone or composites containing LLZO particles

The Latin Leaflet, Number 29

Polymer electrolytes represent the ultimate in terms of desirable properties of energy storage/conversion devices, as they can offer an all-solid-state construction, a wide variety of shapes and sizes, light-weight, low costs, high energy density and safety. Here we present our recent results concerning a novel strategy for preparing efficient polymer membranes which are successfully demonstrated as suitable electrolytes for several energy conversion and storage devices (i.e., Li- and Na-based batteries and DSSCs). Highly ionic conducting polymer electrolytes containing PEO-based functionalities and different components (e.g., Li/Na salts, RTILs, natural biosourced and cellulosic fillers) are successfully prepared via a rapid process and, directly or subsequently, cross-linked via UV irradiation (patent pending, PCT/IT2014/000008). All the prepared materials are thoroughly characterised in terms of their physical, chemical and morphological properties and tested for their electrochemical performances and durability. The UV-curing process on such materials led to the production of elastic and resistant amorphous macromolecular networks. Noticeably increased ionic conductivities are registered (10-3 S cm-1 at RT), along with very stable interfacial and storage stability and wide electrochemical stability windows. The different lab-scale solid-state devices show remarkable performances even at ambient temperature, at the level of those using liquid electrolytes, respect to which demonstrate much greater durability and safety. The obtained findings demonstrate a new, easy and low cost approach to fabricate and tailor-make polymer electrolytes with highly promising prospects for the next generation of advanced flexible energy production and storage devices

Electrocatalytic phenomena in gas phase reactions in solid electrolyte electrochemical cells

The recent literature on electrocatalysis and electrocatalytic phenomena occurring in gas phase reactions on solid, oxygen conducting electrolytes is reviewed. In this field there are a number of different subjects which are treated separately. These are: the use of electrochemical methods to study catalytic phenomena, electrocatalysis proper, the transfer of oxygen at the electrodes or electrolyte, and the (electro)catalytic properties of mixed, electronic and ionic, conducting materials