Batteries, Volume 4, Issue 1 (March 2018) – 13 articles

Graphene nanosheets (GNS) are synthesized from untreated natural graphite (NG) for use as electroactive materials in Li-ion batteries (LIBs), which avoids the pollution-generating steps of purifying graphite. Through a modified Hummer method and subsequent thermal exfoliation, graphitic oxide and graphene were synthesized and characterized structurally, morphologically and chemically. Untreated natural graphite samples contain 45–50% carbon by weight; the rest is composed of different elements such as aluminium, calcium, iron, silicon and oxygen, which are present as calcium carbonate and silicates of aluminium and iron. Our results confirm that in the GO and GNS synthesized, calcium is removed due to oxidation, though other impurities are maintained because they are not affected by the synthesis. Despite the remaining mineral phases, the energy storage capacity of GNS electrodes is very promising. In addition, an electrochemical comparison between GNS and NG demonstrated that the specific capacity in GNS is higher during the whole cycling process, 770 mA·g⁻¹ at 100th cycle, which is twice that of graphite. Full article

The electrochemical performance of zinc particles with 250 μm and 30 μm diameters, coated with Bi₂O₃-Li₂O-ZnO glass is investigated and compared with noncoated zinc particles. Galvanostatic investigations were conducted in the form of complete discharge and charging cycles in electrolyte excess. Coated 30 μm zinc particles provide the best rechargeability after complete discharge. The coatings reached an average charge capacity over 20 cycles of 113 mAh/g compared to the known zero rechargeability of uncoated zinc particles. Proposed reasons for the prolonged cycle life are effective immobilization of discharge products in the glass layer and the formation of percolating metallic bismuth and zinc phases, forming a conductive network through the glass matrix. The coating itself is carried out by mechanical ball milling. Different coating parameters and the resulting coating quality as well as their influence on the passivation and on the rechargeability of zinc–glass composites is investigated. Optimized coating qualities with respect to adhesion, homogeneity and compactness of the glass layer are achieved at defined preparation conditions, providing a glass coating content of almost 5 wt % for 250 μm zinc particles and almost 11 wt % for 30 μm zinc particles. Full article

The aim of the paper is to present the battery equivalent circuit for electric vehicle application. Moreover, the model described below is dedicated to lithium-ion types of batteries. The purpose of this paper is to introduce an efficient and transparent method to develop a battery equivalent circuit model. Battery modeling requires, depending on the chosen method, either significant calculations or a highly developed mathematical model for optimization. The model is evaluated in comparison to the real data measurements, to present the performance of the method. Battery measurements based on charge/discharge tests at a fixed C-rate are presented to show the relation of the output voltage profiles with the battery state of charge. The pulse discharge test is presented to obtain the electric parameters of the battery equivalent circuit model, using a Thévenin circuit. According to the Reverse Trike Ecologic Electric Vehicle (VEECO RT) characteristics used as a case study in this work, new values for vehicle autonomy and battery pack volume based on lithium nickel manganese cobalt oxide cells are evaluated. Full article

Promising electrochemical and dynamical properties, as well as high thermal stability, have been the driving forces behind application of ionic liquids (ILs) and polymerized ionic liquids (PILs) as electrolytes for high-temperature lithium-ion batteries (HT-LIBs). Here, several ternary lithium-salt/IL/PIL electrolytes (PIL_el) have been investigated for synergies of having both FSI and TFSI anions present, primarily in terms of physico-chemical properties, for unique application in HT-LIBs operating at 80 °C. All of the electrolytes tested have low T_g and are thermally stable ≥100 °C, and with TFSI as the exclusive anion the electrolytes (set A) have higher thermal stabilities ≥125 °C. Ionic conductivities are in the range of 1 mS/cm at 100 °C and slightly higher for set A PIL_el, which, however, have lower oxidation stabilities than set B PIL_el with both FSI and TFSI anions present: 3.4–3.7 V vs. 4.2 V. The evolution of the interfacial resistance increases for all PIL_el during the first 40 h, but are much lower for set B PIL_el and generally decrease with increasing Li-salt content. The higher interfacial resistances only influence the cycling performance at high C-rates (1 C), where set B PIL_el with high Li-salt content performs better, while the discharge capacities at the 0.1 C rate are comparable. Long-term cycling at 0.5 C, however, shows stable discharge capacities for 100 cycles, with the exception of the set B PIL_el with high Li-salt content. Altogether, the presence of both FSI and TFSI anions in the PIL_el results in lower ionic conductivities and decreased thermal stabilities, but also higher oxidation stabilities and reduced interfacial resistances and, in total, result in an improved rate capability, but compromised long-term capacity retention. Overall, these electrolytes open for novel designs of HT-LIBs. Full article

Continuing from a special issue in Batteries in 2016, nineteen new papers focusing on recent research activities in the field of nickel/metal hydride (Ni/MH) batteries have been selected for the 2017 Special Issue of Ni/MH Batteries. These papers summarize the international joint-efforts in Ni/MH battery research from BASF, Wayne State University, Michigan State University, FDK Corp. (Japan), Institute for Energy Technology (Norway), Central South University (China), University of Science and Technology Beijing (China), Zhengzhou University of Light Industry (China), Inner Mongolia University of Science and Technology (China), Shenzhen Highpower (China), and University of the Witwatersrand (South Africa) from 2016–2017 through reviews of AB₂ metal hydride alloys, Chinese and EU Patent Applications, as well as descriptions of research results in metal hydride alloys, nickel hydroxide, electrolyte, and new cell type, comparison work, and projections of future works. Full article

One of the primary targets of current research in the field of energy storage and conversion is the identification of easy, low-cost approaches for synthesizing cell active materials. Herein, we present a novel method for preparing nanometric slabs of Na_0.44MnO₂, making use of the eco-friendly urea within a solution synthesis approach. This kind of preparation greatly reduces the time of reaction, decreases the thermal treatment temperature, and allows the obtaining of particles with smaller dimensions compared with those obtained through conventional solid-state synthesis. Such a decrease in particle size guarantees improved electrochemical performance, particularly at high current densities, where kinetic limitations become relevant. Indeed, the materials produced via solution synthesis outperform those prepared via solid-state synthesis both at 2 C, (95 mA h g⁻¹ vs. 85 mA h g⁻¹, respectively) and 5 C, (78 mA h g⁻¹ vs. 68.5 mA h g⁻¹, respectively). Additionally, the former material is rather stable over 200 cycles, with a high capacity retention of 75.7%. Full article

The lithium ion battery (LIB) has proven to be a very reliably used system to store electrical energy, for either mobile or stationary applications. Among others, TiO₂-based anodes are the most attractive candidates for building safe and durable lithium ion batteries with high energy density. A variety of TiO₂ nanostructures has been thoroughly investigated as anodes in LIBs, e.g., nanoparticles, nanorods, nanoneedles, nanowires, and nanotubes discussed either in their pure form or in composites. In this review, we present the recent developments and breakthroughs demonstrated to synthesize safe, high power, and low cost nanostructured titania-based anodes. The reader is provided with an in-depth review of well-oriented TiO₂-based nanotubes fabricated by anodic oxidation. Other strategies for modification of TiO₂-based anodes with other elements or materials are also highlighted in this report. Full article

The advent of large-scale renewable energy generation and electric mobility is driving a growing need for new electrochemical energy storage systems. Metal-air batteries, particularly zinc-air, are a promising technology that could help address this need. While experimental research is essential, it can also be expensive and time consuming. The utilization of well-developed theory-based models can improve researchers’ understanding of complex electrochemical systems, guide development, and more efficiently utilize experimental resources. In this paper, we review the current state of metal-air batteries and the modeling methods that can be implemented to advance their development. Microscopic and macroscopic modeling methods are discussed with a focus on continuum modeling derived from non-equilibrium thermodynamics. An applied example of zinc-air battery engineering is presented. Full article

In order to meet the sophisticated demands for large-scale applications such as electro-mobility, next generation energy storage technologies require advanced electrode active materials with enhanced gravimetric and volumetric capacities to achieve increased gravimetric energy and volumetric energy densities. However, most of these materials suffer from high 1st cycle active lithium losses, e.g., caused by solid electrolyte interphase (SEI) formation, which in turn hinder their broad commercial use so far. In general, the loss of active lithium permanently decreases the available energy by the consumption of lithium from the positive electrode material. Pre-lithiation is considered as a highly appealing technique to compensate for active lithium losses and, therefore, to increase the practical energy density. Various pre-lithiation techniques have been evaluated so far, including electrochemical and chemical pre-lithiation, pre-lithiation with the help of additives or the pre-lithiation by direct contact to lithium metal. In this review article, we will give a comprehensive overview about the various concepts for pre lithiation and controversially discuss their advantages and challenges. Furthermore, we will critically discuss possible effects on the cell performance and stability and assess the techniques with regard to their possible commercial exploration. Full article

Li-ion cell designs, component integrity, and manufacturing processes all have critical influence on the safety of Li-ion batteries. Any internal defective features that induce a short circuit, can trigger a thermal runaway: a cascade of reactions, leading to a device fire. As consumer device manufacturers push aggressively for increased battery energy, instances of field failure are increasingly reported. Notably, Samsung made a press release in 2017 following a total product recall of their Galaxy Note 7 mobile phone, confirming speculation that the events were attributable to the battery and its mode of manufacture. Recent incidences of battery swelling on the new iPhone 8 have been reported in the media, and the techniques and lessons reported herein may have future relevance. Here we look deeper into the key components of one of these cells and confirm evidence of cracking of electrode material in tightly folded areas, combined with a delamination of surface coating on the separator, which itself is an unusually thin monolayer. We report microstructural information about the electrodes, battery welding attributes, and thermal mapping of the battery whilst operational. The findings present a deeper insight into the battery’s component microstructures than previously disseminated. This points to the most probable combination of events and highlights the impact of design features, whilst providing structural considerations most likely to have led to the reported incidences relating to this phone. Full article

Li-ion battery (LIB) full cells comprised of TiO₂-nanotube (TiO₂-nt) and LiFePO₄ (LFP) electrodes and either a conventional organic solvent based liquid electrolyte or an ionic liquid based electrolyte have been cycled at 80 °C. While the cell containing the ionic liquid based electrolyte exhibited good capacity retention and rate capability during 100 cycles, rapid capacity fading was found for the corresponding cell with the organic electrolyte. Results obtained for TiO₂-nt and LFP half-cells indicate an oxidative degradation of the organic electrolyte at 80 °C. In all, ionic liquid based electrolytes can be used to significantly improve the performance of LIBs operating at 80 °C. Full article

The stationary power market, particularly telecommunications back-up (telecom) applications, is dominated by lead-acid batteries. A large percentage of telecom powerplants are housed in outdoor enclosures where valve-regulated lead-acid (VRLA) batteries are commonly used because of their low-maintenance design. Batteries in these enclosures can be exposed to temperatures which can exceed 70 °C, significantly reducing battery life. Nickel–cadmium (Ni–Cd) batteries have traditionally been deployed in hotter locations as a high-temperature alternative to VRLA. This paper compares the performances of nickel/metal hydride (Ni/MH), Ni–Cd, and VRLA batteries in a simulated telecom environment according to published testing standards. Among these three choices, Ni/MH batteries showed the best overall performance, suggesting substantially longer operating life in high temperature stationary use. Full article