In this paper, the degradation processes of commercial supercapacitors aged at 2.7 V and 65 °C for 2000 h were studied. The crystallinity, thermal stability, and specific surface areas of the carbon electrodes of the supercapacitors were measured. Significant changes and degradations in the carbon electrodes were observed for the aged supercapacitors. New functional groups were also found on the surface of the electrodes. The degradation of the lattice structures and the reduction in the specific surface area were as well observed for the aged supercapacitors. It was suggested that the aging of supercapacitors significantly changed the electrode surface which affects considerably electrical properties and functionality of supercapacitors. We have also performed experiments which suggest that the aging effect on the electrode is not uniformly distributed through its length.

The electrochemical storage performance of anatase TiO2 nanotubes (NT) is compared to the performance of TiO2 nanotubes covered by sulfur. Charge/discharge curves and cycling performance of TiO2 NT with and without sulfur deposition with respect to lithium anodes are demonstrated in electrochemical test cells. At 0.5C cycle rate the TiO2 NT exhibited a first cycle specific charge/discharge capacity of 180/155 mAh/g, whereas the TiO2 NT deposited with sulfur showed a remarkably higher performance at 0.5C cycle rate with first cycle charge/ discharge specific capacities of 258/260 mAh/g and a coulombic efficiency of 98%.

LiFePO4 has shown considerable promise as a cathode material in Li-ion batteries due to its stability, low toxicity and high cyclability. However, the data on thermodynamic stability of olivine phase FePO4 (o-FePO4), the delithiated form of o-LiFePO4, remains scarce and contradictory. In this work, o-FePO4 was synthesized by chemical delithiation of o-LiFePO4 and characterized structurally and thermally. X-ray diffraction and absorption data indicate pure olivine phase, but with residual amount of Fe2+, most likely due to incomplete delithiation. Differential scanning calorimetry and thermal gravimetric analysis reveal that o-LixFePO4 decomposes exothermally above 550 °C with about 9% weight loss, the products being trigonal phase FePO4, Fe7(PO4)6, and LiPO3.

Current collectors in lithium ion batteries are considered to give the electronic conduction to the electrode materials without electrochemical reactions. However, once the current collectors are thermally treated with active electrode materials, thermally treated current collectors might induce electrochemical reaction that affects the whole cell performance due to the interfacial layer formed by the thermal treatment. In this work, Ni foam and Cu foil current collectors were investigated to understand their capacity contribution and electrochemical properties after thermal treatment.

Manganese oxide electrodes are synthesized by anodic deposition on Au coated Si substrates from acetate-containing aqueous solutions. By changing the deposition parameters including deposition current density, electrolyte composition, pH and temperature, a series of nanocrystalline manganese oxide electrodes with various morphologies (non–uniform continuous coatings, rod–like structures, aggregated rods and thin sheets) is obtained. Detailed microstructural characterization of as-deposited electrodes is conducted using scanning electron microscopy (SEM).

Electrochemical analysis using cyclic voltammetry showed that manganese oxide electrodes with rod–like and thin sheet morphology exhibit enhanced electrochemical performance by improving manganese oxide utilization. The highest specific capacitance (~230 F g−1) and capacitance retention rates (~88%) are obtained for manganese oxide thin sheets after 250 cycles in 0.5M Na2SO4 at 20 mV s−1.

Effect of surfactants present in alkaline solutions on the capacitance of carbon electrodes has been studied. Different types of surfactants have been selected for this target. Concentration of these electrolyte additives was 0.005 mol L-1. Decreasing the surface tension in the electrode/electrolyte interface allows better penetration of electrolyte into the pores. Detailed analysis of capacitance versus current load, frequency dependence as well as self-discharge, cyclability and behaviour in wider voltage window proved a useful effect of Triton X-100 on capacitor operating in alkaline solution. Influence of surfactant concentration has also been investigated.

Automotive components, for the most part, are designed to last for the life of the vehicle. This is especially true for more expensive subsystems. As we move towards electrified vehicles with large traction batteries, it becomes increasingly important to (a) reduce the cost of the batteries and (b) improve battery life. This life challenge for the traction battery is quite different from that of most consumer electronics applications, which often require no more than a few years of life and a few hundred cycles of full charge and discharge. In this paper, we provide context for the automotive battery landscape and subsequently introduce a potential solution pathway to the cycle life problem associated with high capacity negative electrodes for lithium ion batteries. The approach is based on a solid (in the substantially lithiated state) to liquid (in the absence of significant lithium) transition for the gallium electrode. Because of gallium’s low melting point (29°C), heating the cell to just above ambient temperature transforms the electrode to a semi-liquid state, cracks vanish, to a large extent, and the electrode heals.