Batteries, Volume 3, Issue 3 (September 2017) – 9 articles

The electrochemical performance and failure mechanisms of Ni/MH batteries made with a series of the Fe-substituted A₂B₇ superlattice alloys as the negative electrodes were investigated. The incorporation of Fe does not lead to improved cell capacity or cycle life at either room or low temperature, although Fe promotes the formation of a favorable Ce₂Ni₇ phase. Fe-substitution was found to inhibit leaching of Al from the metal hydride negative electrode and promote leaching of Co, which could potentially extend the cycle life of the positive electrode. The failure mechanisms of the cycled cells with the Fe-substituted superlattice hydrogen absorbing alloys were analyzed by scanning electron microscopy, energy dispersive spectroscopy and inductively coupled plasma analysis. The failure of cells with Fe-free and low Fe-content alloys is mainly attributed to the pulverization of the metal hydride alloy. Meanwhile, severe oxidation/corrosion of the negative electrode is observed for cells with high Fe-content alloys, resulting in increased internal cell resistance, formation of micro-shortages in the separator and eventual cell failure. Full article

C14 Laves phase alloys play a significant role in improving the performance of nickel/metal hydride batteries, which currently dominate the 1.2 V consumer-type rechargeable battery market and those for hybrid electric vehicles. In the current study, the properties of C14 Laves phase based metal hydride alloys are reviewed in relation to their electrochemical applications. Various preparation methods and failure mechanisms of the C14 Laves phase based metal hydride alloys, and the influence of all elements on the electrochemical performance, are discussed. The contributions of some commonly used constituting elements are compared to performance requirements. The importance of stoichiometry and its impact on electrochemical properties is also included. At the end, a discussion section addresses historical hurdles, previous trials, and future directions for implementing C14 Laves phase based metal hydride alloys in commercial nickel/metal hydride batteries. Full article

A combination of analytic tools and electrochemical testing was employed to study the contributions of Palladium (Pd) in a Zr-based AB₂ metal hydride alloy (Ti₁₂Zr_22.8V₁₀ Cr_7.5Mn_8.1Co₇Ni_32.2Al_0.4). Pd enters the A-site of both the C14 and C15 Laves phases and shrinks the unit cell volumes, which results in a decrease of both gaseous phase and electrochemical hydrogen storage capacities. On the other hand, the addition of Pd benefits both the bulk transport of hydrogen and the surface electrochemical reaction. Improvements in high-rate dischargeability and low-temperature performances are solely due to an increase in surface catalytic ability. Addition of Pd also decreases the surface reactive area, but such properties can be mediated through incorporation of additional modifications with rare earth elements. A review of Pd-addition to other hydrogen storage materials is also included. Full article

Patent applications in the field of nickel/metal hydride (Ni/MH) batteries are reviewed to provide a solid technology background and directions for future developments. As the fourth review article in the series of investigations into intellectual properties in this area, this article focuses on 126 patent applications filed by European companies at the European Patent Office, while the earlier articles dealt with those from USA, Japan, and China. The history and current status of the key companies in the Ni/MH battery business are briefly discussed. These companies are categorized by their main roles in the industry, i.e., battery manufacturer, metal hydride alloy supplier, separator supplier, and others. While some European companies are pioneers in bringing the Ni/MH product to customers, others have made significant contributions to the development of the technology, especially in the button cell, bipolar cell, and separator areas. Full article

Both the patents issued and applications filed in China regarding nickel/metal hydride (Ni/MH) battery technology are reviewed in the article. Selective works from 39 battery manufactures, 9 metal hydride alloy suppliers, 13 Ni(OH)₂ suppliers, 20 hardware suppliers, 19 system integrators, universities, and 12 research institutes are included. China being the country that produces the most Ni/MH batteries is relatively weak in the innovation part of intellectual properties when compared to the US and Japan. However, it produces very many patents in the areas of cell structure optimization and production processes. Designs of high-capacity, high-power, and low-cost cells are compared from different manufacturers. Full article

This paper presents a new control strategy for isolated micro-grids including wind turbines (WT), fuel cells (FC), photo-voltaic (PV) and battery energy storage systems (BESS). FC have been used in parallel with BESSs in order to increase their lifetime and efficiency. The changes in some parameters such as wind speed, sunlight, and consumption, lead to improper performance of droop. To overcome this challenge, a new intelligent method using a combination of fuzzy controller and cuckoo optimization algorithm (COA) techniques for active power controllers in isolated networks is proposed. In this paper, COA is compared with genetic algorithm (GA) and particles swarm optimization algorithm (PSO). In order to show efficiency of the proposed controller, this optimal controller has been compared with droop, optimized droop, and conventional fuzzy methods, the dynamic analysis of the island is implemented to assess the behavior of isolated generations accurately and simulation results are reported. Full article

Herein, we present a comparison of the electrochemical hydrogen-storage characteristics of two state-of-art Laves phase-based metal hydride alloys (Zr_21.5Ti_12.0V_10.0Cr_7.5Mn_8.1Co_8.0Ni_32.2Sn_0.3Al_0.4 vs. Zr_25.0Ti_6.5V_3.9Mn_22.2Fe_3.8Ni_38.0La_0.3) prepared by induction melting and hydrogen decrepitation. The relatively high contents of lighter transition metals (V and Cr) in the first composition results in an average electron density below the C14/C15 threshold $\left(e/a~6.9\right)$ and produces a C14-predominated structure, while the average electron density of the second composition is above the C14/C15 threshold and results in a C15-predominated structure. From a combination of variations in composition, main phase structure, and degree of homogeneity, the C14-predominated alloy exhibits higher storage capacities (in both the gaseous phase and electrochemical environment), a slower activation, inferior high-rate discharge, and low-temperature performances, and a better cycle stability compared to the C15-predominated alloy. The superiority in high-rate dischargeability in the C15-predominated alloy is mainly due to its larger reactive surface area. Annealing of the C15-predominated alloy eliminates the ZrNi secondary phase completely and changes the composition of the La-containing secondary phase. While the former change sacrifices the synergetic effects, and degrades the hydrogen storage performance, the latter may contribute to the unchanged surface catalytic ability, even with a reduction in total volume of metallic nickel clusters embedded in the activated surface oxide layer. In general, the C14-predominated alloy is more suitable for high-capacity and long cycle life applications, and the C15-predominated alloy can be used in areas requiring easy activation, and better high-rate and low-temperature performances. Full article

Lithium-ion battery on-line remaining useful life (RUL) prediction has become increasingly popular. The capacity and internal resistance are often used as the batteries’ health indicator (HI) for quantifying degradation and predicting the RUL. However, the capacity and internal resistance are too difficult to measure on-line due to the batteries’ internal state variables being inaccessible to sensors under operational conditions. In addition, measuring these variables requires accurate measurement devices, which can be expensive, and have limited applicability in practice. In this paper, a novel HI is extracted from the operating parameters of lithium-ion batteries for degradation models and RUL prediction. Moreover, the Box–Cox transformation is applied to improve the correlation between the extracted HI and the battery’s real capacity. Then, Pearson and Spearman correlation analyses are utilized to assess the similarity between the real capacity and the estimated capacity derived from the HI. An optimized gray model GM(1,1) is employed to predict the RUL based on the presented HI. The experimental results show that the proposed method is effective and accurate for battery degradation modeling and RUL prediction. Full article

The potentially high gravimetric capacities of intermetallic anodes, coupled with the low cost and readily available materials used in sodium-ion batteries, has generated interest in antimony—an anode capable of alloying with sodium. However, presently there are few synthetic routes to antimony particles for use in sodium-ion batteries. One pot, sol-gel synthetic routes from readily available, chloride-free precursors have been developed. The resulting products have been characterized and, from this data, several key parameters’ optimization have been identified and are presented here. Finally, using this information, some initial optimization has been carried out, which resulted in minor improvements to the physical and electrochemical properties of the resulting product. Full article