Solid-state based battery technology offers, in principle, the largest temperature range (from room temperature to 500 °C) of any battery technology. In fluoride based batteries, the chemical reaction used to create electrical energy is a solid-state reaction of a metal with fluoride anion [1]. Among the various types of solid preparation techniques, the mechanochemical synthesis has been recognized as a powerful route to novel, high-performance, and low-cost materials [2]. Thus, a mixed and highly disordered fluoride phase with retained cubic symmetry can be obtained with a very high Fˉ diffusivity [3].

In our group, a series of new electrolytes was developed, namely LaF3-BaF2-KF solid solutions, using mechanosynthesis method. The cubic structure of the product was confirmed by XRD. The nanoscale nature and morphology of the samples were characterized by SEM and TEM. First Solid-state electrochemical cells were built with LiF based composite cathode, LaF3-BaF2-KF derived electrolyte and Fe based composite anode.

Olivine (LiFePO4)-carbon nanofibre composites were synthesized through a combination of electrospinning and solvothermal methods. Morphology, distribution and crystal structure of these composites were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Electrochemical properties of synthesized LiFePO4-carbon fibre composite cathodes have been studied in litium ion coin cells by means of galvanostatic cycling and cyclic voltammetry. As compared to pristine LiFePO4, there was significant improvement in the specific capacity (˜25% at 0.1C rate) of LiFePO4 - ECNF owing to the improved conductivity.

We have employed anodic oxidation of Ti foils to prepare self-organized TiO2 nanotube arrays which show enhanced electrochemical properties for applications as Li-ion battery electrode materials. The lengths and pore diameters of TiO2 nanotubes can be finely tuned by varying voltage, electrolyte composition, or anodization time. The as-prepared nanotubes are amorphous and can be converted into anatase nanotubes with heat treatment at 480oC and nanotubes of mixed anatase/rutile phases by heating at 580oC. The morphological features of nanotubes remain unchanged after annealing. Amorphous nanotubes with a length of 3.0 μm and an outer diameter of 125 nm delivers a capacity of 91.2 μA h cm-2 at a current density of 400 μA cm-2, while those with a length of 25 μm and an outer diameter of 158 nm display a capacity of 533 μA h cm-2. The 3-μm long anatase nanotubes and nanotubes of mixed phases show lower capacities of 53.8 μA h cm-2 and 63.1 μA h cm-2, respectively at the same current density. The amorphous TiO2 nanotubes with a length of 1.9 μm exhibit a capacity five times higher than that of TiO2 compact layer even when the nanotube array is cycled at a current density 80 times higher than that for the compact layer. The amorphous nanotubes show excellent capacity retention ability over 50 cycles. Cycled nanotubes show little change in morphology compared to the nanotubes before cycling, indicating the high structural stability of TiO2 nanotubes.

Lithium borophosphate glasses 0.45Li2O-(0.55-x)P2O5-xB2O3 (where 0 ≤ x ≤ 0.40) were investigated focusing on the influence of cation mobility changes due to mixed glass former effect. It was found that glass transition temperature (Tg) increases and molar volume decreases with B2O3 addition. X-ray photoelectron spectroscopy (XPS) spectra showed that besides P-O-P, B-O-B and P=O, P-O-, B-O- bond peaks, an intermediate O1s peak due to P-O-B bonds emerges in glasses with B2O3 contents x ≥ 0.15. Molecular dynamics (MD) simulations for the same systems have been performed with an optimized potential, fitted to match bond lengths, coordination numbers and ionic conductivity (σdc). Structural effects on ion transport as the origin of the mixed glass former effect can be quantified by applying the bond valence analysis (BV) approach to the equilibrated MD trajectories.

Fabrication of all-solid-state Li battery has been strongly required to overcome safety issue of present Li battery. One of promising structures for ceramics electrolyte in all-solid-state battery is 2-layered structure composed of 3 dimensionally ordered macroporous layer (3DOM) and dense layer. In this study, we prepared LLT ceramics electrolyte with the 2-layered structure by suspension filtration method. Thicknesses of the dense and the porous layers were about 17 and 111 μm, respectively. The porous layer involved uniform pores of 1.8 μm in diameter. An electrochemical property of LiMn2O4/2-layered LLT composite, prepared by impregnation of precursor sol for LiMn2O4 into the pores followed by calcination, was tested. A rechargeable behavior of the composite electrode was clearly observed. From this result, it can be said that the composite can work as rechargeable battery. The discharge capacity of the composite was 27 mA h g-1.

LiFePO4/graphene-oxide (GNO) composites were prepared by co-precipitation method. Their structure and morphology were investigated by X-ray diffraction, Fourier transform infrared spectra, field emission scanning electron microscopy, and transmission electron microscopy. A low content of GNO can be uniformly dispersed in the matrix of LiFePO4 nano particles, while at a higher content, GNO will aggregate severely and has a negative effect on the electrochemical performance of LiFePO4. Further heat treatment can improve the crystallinity of LiFePO4, and improve the electrochemical performance of LiFePO4 with a relatively low content of GNO.

Using a hard exotemplate procedure, hierarchically structured carbonaceous foams have been designed, using silica monolith as inorganic template and phenolic resin as carbon precursor. The open cell carbonaceous monoliths exhibit specific surface areas from 500 to 800 m2.g-1, essentially based on microporosity and macropores ranging from 0.05 up to 50 μm. Application as electrochemical energy storage devices have been checked and discuss inhere.