Past developments and the future of nickel electrode cell technology

2016

J Appl Electrochem

NiFe batteries are emerging as an important energy storage technology but suffer from a hydrogenproducing side reaction which has safety implications and reduces coulombic efficiency. This manuscript describes a systematic improvement approach for the production of Fe/ FeS-based anodes at high concentrations of iron sulphide. Electrodes were made by mixing varying amounts of iron sulphide in such a way that its concentration ranges from between 50 and 100 % (compositions expressed on a PTFE-free basis). Electrode performance was evaluated by cycling our in-house-produced anodes against commercially available nickel electrodes. The results show that anodes produced with larger concentrations outperform their lower concentration counterparts in terms of coulombic efficiency although a slight decrease in the overall cell performance was found when using pure FeS anodes. At high FeS concentrations a hydrogen-producing side reaction has been virtually eliminated resulting in coulombic efficiencies of over 95 %. This has important implications for the safety and commercial development of NiFe batteries. Graphical AbstractKeywords FeS anode Á FeS electrode Á NiFe

Section: Introductionmentioning

confidence: 99%

“…Particularly important are to increase the cell efficiency, preventing electrolyte decomposition and increasing both energy and power densities [2,3].…”

Section: Introductionmentioning

confidence: 99%

Towards the development of safe and commercially viable nickel–iron batteries: improvements to Coulombic efficiency at high iron sulphide electrode formulations

2016

J Appl Electrochem

“…Unfortunately there are still many obstacles preventing a large scale utilization of these cells, such as considerable evolution of hydrogen, relatively low efficiency, low energy and power densities. 9,19 From these problems, the evolution of hydrogen is probably the most important, for it lowers the overall cell performance by diverting part of the energy to be stored in decomposing the electrolyte. Therefore, we have utilized our in-house built Bi 2 S 3 /Fe based anodes to test different electrolyte systems, so this problem would be mitigated and the overall cell performance would be enhanced.…”

mentioning

confidence: 99%

The Effect of Electrolyte Additives on the Performance of Iron Based Anodes for NiFe Cells

2015

J. Electrochem. Soc.

Aqueous electrolyte formulations for NiFe cells were prepared by using lithium hydroxide and potassium sulfide additives. The incidence of each additive on the overall performance of the NiFe cell was evaluated by cycling our in-house built bismuth sulfide based iron electrodes against commercially available nickel electrodes. In order to explore the composition space relevant to our formulations, a 12 replicates 3 × 4 full factorial experimental design was proposed to efficiently investigate the combined effect of both additives. Our experimental results suggest potassium sulfide enhances the performance of the battery. The role of lithium hydroxide is less clear but the evidence supports that it would increase coulombic efficiency to a lesser degree than potassium sulfide. This article demonstrates that by using a relatively simple manufacturing technique and low cost materials, it is possible to develop cost effective solutions to store large amounts of energy coming from renewables. There is a growing demand of energy from renewable sources; [1][2][3][4][5][6] however, temporary energy profiles and the availability of sun light restrict the use of such sources. Therefore, energy storage emerges as the natural solution to the asynchronous problem between energy generation and demand. 7,8 There are many forms of energy storage (compressed air, hydroelectricity, electrochemical energy storage, etc.) with the potential to store grid amounts of energy coming from renewables. However, any practical solution must be efficient, safe, environmentally friendly and cost effective.It is well known that organic electrolyte based batteries exhibit much larger energy and power density than their conventional aqueous based counterparts. Therefore, non-aqueous batteries has become the industry standard for most mobile applications (portable computers, smart telephones, etc.). Due to the flammable nature of organic solvents, safety measurements are of overriding importance when dealing with such applications. Implementing safety measurements to protect your laptop's battery is one thing, but securing energy for a much larger application, such as an airport, is a completely different story; in this case, the implementation of safety systems would be very challenging and expensive as well. This is no longer the case with aqueous batteries, where the electrolyte itself would reduce the risk of fire. In addition, the abundance and lower cost of raw materials required to produce aqueous batteries is another important aspect to consider.Essentially, NiFe cells are secondary batteries which utilize iron based anodes, nickel based cathodes and concentrated solutions of KOH as electrolyte systems. This technology felt out of favor with the advent of cheaper lead-acid cells; however, there is a renewed interest on these batteries arising from their environmentally friendliness, longevity, and tolerance to electrical abuse (such as overcharge, over-discharge, not being used for extended periods and short-circuit conditions) and compatib...

“…Moreover, it has been recognized that this technology would be suitable for relatively low specific energy applications (30e50 W h kg À1 ) [12]. As a consequence, there are good reasons to foresee a large scale utilization of this technology; but there is a plethora of challenges to overcome first, such as increasing the cell efficiency, preventing electrolyte decomposition and therefore the evolution of hydrogen, and increasing energy and power densities [13,14].…”

Section: Introductionmentioning

confidence: 99%

“…Eq. (1) illustrates the charging and discharging (forward and backward reactions respectively) processes of an iron electrode under alkaline conditions [14,23,24].…”

Section: Introductionmentioning

confidence: 99%

Controlling hydrogen evolution on iron electrodes

2015 3rd International Renewable and Sustainable Energy Conference (IRSEC)

2015

Available online xxx Keywords:Iron electrode NiFe Electrolyte decompositionCell performance Hydrogen evolution a b s t r a c t Aiming to develop a cost effective means to store large amounts of electric energy, NiFe batteries were produced and tested under galvanostatic conditions at room temperature.Multiple regression analysis was conducted to develop predictive equations that establish a link between hydrogen evolution and electrode manufacturing conditions, over a wide range of electrode/electrolyte systems. Basically, the intent was to investigate the incidence of lithium hydroxide and potassium sulphide as electrolyte additives on cell performance. With this in mind, in-house built Fe/FeS based electrodes were cycled against commercially available nickel electrodes on a three electrode cell configuration. A 3 Â 4 full factorial experimental design was proposed to investigate the combined effect of the aforementioned electrolyte additives on cell performance. As a consequence, data from 144 cells were finally used in conducting the analysis and finding the form of the predictive equations. Our findings suggest that at the level of confidence alpha ¼ 0.05, the presence of relatively large amounts of the soluble bisulphide would enhance the performance of the battery by reducing electrolyte decomposition.