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To investigate the influence of cell formats during a cell development programme, lithium-ion cells have been prepared in three different formats. Coin cells, single layer pouch cells, and stacked pouch cells gave a range of scales of almost three orders of magnitude. The cells used the same electrode coatings, electrolyte and separator. The performance of the different formats was compared in long term cycling tests and in measurements of resistance and discharge capacities at different rates. Some test results were common to all three formats. However, the stacked pouch cells had higher discharge capacities at higher rates. During cycling tests, there were indications of differences in the predominant degradation mechanism between the stacked cells and the other two cell formats. The stacked cells showed faster resistance increases, whereas the coin cells showed faster capacity loss. The difference in degradation mechanism can be linked to the different thermal and mechanical environments in the three cell formats. The correlation in the electrochemical performance between coin cells, single layer pouch cells, and stacked pouch cells shows that developments within a single cell format are likely to lead to improvements across all cell formats.
Grace Bridgewater; Matthew Capener; James Brandon; Michael Lain; Mark Copley; Emma Kendrick. A Comparison of Lithium-Ion Cell Performance across Three Different Cell Formats. Batteries 2021, 7, 38 .
AMA StyleGrace Bridgewater, Matthew Capener, James Brandon, Michael Lain, Mark Copley, Emma Kendrick. A Comparison of Lithium-Ion Cell Performance across Three Different Cell Formats. Batteries. 2021; 7 (2):38.
Chicago/Turabian StyleGrace Bridgewater; Matthew Capener; James Brandon; Michael Lain; Mark Copley; Emma Kendrick. 2021. "A Comparison of Lithium-Ion Cell Performance across Three Different Cell Formats." Batteries 7, no. 2: 38.
Commercial lithium ion cells with different power: energy ratios were disassembled, to allow the electrochemical performance of their electrodes to be evaluated. Tests on coin cell half cells included rate tests (continuous and pulsed), resistance measurements, and extended pulse tests. Pulse power tests at high rates typically showed three limiting processes within a 10 s pulse; an instantaneous resistance increase, a solid state diffusion limited stage, and then electrolyte depletion/saturation. On anodes, the third process can also be lithium plating. Most of the cells were rated for a 10 C continuous discharge, and the cathode charging voltage at 10 C was around 4.2 V. For anodes, the maximum charge current to avoid a negative voltage was 3–5 C. Negative anode voltages do not necessarily mean that lithium plating has occurred. However, lithium deposits were observed on all the anodes after 5000 pulse sequences with 10 s pulses at ± 20 C.
Michael.J. Lain; Emma Kendrick. Understanding the limitations of lithium ion batteries at high rates. Journal of Power Sources 2021, 493, 229690 .
AMA StyleMichael.J. Lain, Emma Kendrick. Understanding the limitations of lithium ion batteries at high rates. Journal of Power Sources. 2021; 493 ():229690.
Chicago/Turabian StyleMichael.J. Lain; Emma Kendrick. 2021. "Understanding the limitations of lithium ion batteries at high rates." Journal of Power Sources 493, no. : 229690.
The impacts on battery cell ageing from high current operation are investigated using commercial cells. This study utilised two tests–(i) to establish the maximum current limits before cell failure and (ii) applying this maximum current until cell failure. Testing was performed to determine how far cycling parameters could progress beyond the manufacturer’s recommendations. Current fluxes were increased up to 100 C cycling conditions without the cell undergoing catastrophic failure. Charge and discharge current capabilities were possible at magnitudes of 1.38 and 4.4 times, respectively, more than that specified by the manufacturer’s claims. The increased current was used for longer term cycling tests to 500 cycles and the resulting capacity loss and resistance increase was dominated by thermal fatigue of the electrodes. This work shows that there is a discrepancy between manufacturer-stated current limits and actual current limits of the cell, before the cell undergoes catastrophic failure. This presumably is based on manufacturer-defined performance and lifetime criteria, as well as prioritised safety factors. For certain applications, e.g., where high performance is needed, this gap may not be suitable; this paper shows how this gap could be narrowed for these applications using the testing described herein.
Justin Holloway; Faduma Maddar; Michael Lain; Melanie Loveridge; Mark Copley; Emma Kendrick; David Greenwood. Determining the Limits and Effects of High-Rate Cycling on Lithium Iron Phosphate Cylindrical Cells. Batteries 2020, 6, 57 .
AMA StyleJustin Holloway, Faduma Maddar, Michael Lain, Melanie Loveridge, Mark Copley, Emma Kendrick, David Greenwood. Determining the Limits and Effects of High-Rate Cycling on Lithium Iron Phosphate Cylindrical Cells. Batteries. 2020; 6 (4):57.
Chicago/Turabian StyleJustin Holloway; Faduma Maddar; Michael Lain; Melanie Loveridge; Mark Copley; Emma Kendrick; David Greenwood. 2020. "Determining the Limits and Effects of High-Rate Cycling on Lithium Iron Phosphate Cylindrical Cells." Batteries 6, no. 4: 57.
Sulphur, boron and phosphorous containing electrolyte additives were evaluated in cells containing pristine electrodes from a commercial EV lithium ion cell against a standard baseline electrolyte. Following formation and a full cell ageing step, cycling performance and impedance spectroscopy were used to elucidate the most effective additives. The additive tris trimethyl silyl phosphite (TTSPi) showed the most promise; with improved cell capacities and reduced impedances observed after formation. X-ray photoelectron spectroscopy (XPS) measurements on anode elemental surface profiles were correlated with the electrochemical performance. It was observed that increased lithium fluoride content on the surface of the anodes typically produced cells with lower impedance. Sulphur containing additives also showed improved cell behaviours; and the decomposition and chemical reactions of these compounds at the anode surface is discussed in detail. The main influence of TTSPi was to reduce the amount of oxygen (C=O) and sulphur in the electrolyte interphase (SEI) layer; to be replaced with hydrocarbons.
Micheal J. Lain; Irene Rubio Lopez; Emma Kendrick. Electrolyte Additives in Lithium Ion EV Batteries and the Relationship of the SEI Composition to Cell Resistance and Lifetime. Electrochem 2020, 1, 200 -216.
AMA StyleMicheal J. Lain, Irene Rubio Lopez, Emma Kendrick. Electrolyte Additives in Lithium Ion EV Batteries and the Relationship of the SEI Composition to Cell Resistance and Lifetime. Electrochem. 2020; 1 (2):200-216.
Chicago/Turabian StyleMicheal J. Lain; Irene Rubio Lopez; Emma Kendrick. 2020. "Electrolyte Additives in Lithium Ion EV Batteries and the Relationship of the SEI Composition to Cell Resistance and Lifetime." Electrochem 1, no. 2: 200-216.
The formation process and subsequent cell ageing (conditioning) protocols for a commercial EV lithium ion cell chemistry have been studied understand their effect on the electrochemical performance and chemical interface. The temperature and duration were varied for both the formation and conditioning steps, and the state of charge was investigated for the conditioning step. The optimum cell ageing temperature was shown to be dependent on the formation conditions. After formation at room temperature, a longer cycle life was observed when ageing was performed at 5 o C. After formation at 5 o C, ageing at 45 o C gave the best cycle life. The formation process creates an initial interface layer from reduction of the electrolyte, which rearranges chemically as the cell ages. Surface analysis of the graphite showed increased quantities of boron and phosphorus in the interface layer after ageing at 45 o C, and the fluorine content increased by 20% during ageing. For low temperature formation, greater levels of lithium and oxygen were observed, which subsequently decreased during ageing.
Irene Rubio Lopez; Michael J. Lain; Emma Kendrick. Optimisation of Formation and Conditioning Protocols for Lithium‐Ion Electric Vehicle Batteries. Batteries & Supercaps 2020, 3, 900 -909.
AMA StyleIrene Rubio Lopez, Michael J. Lain, Emma Kendrick. Optimisation of Formation and Conditioning Protocols for Lithium‐Ion Electric Vehicle Batteries. Batteries & Supercaps. 2020; 3 (9):900-909.
Chicago/Turabian StyleIrene Rubio Lopez; Michael J. Lain; Emma Kendrick. 2020. "Optimisation of Formation and Conditioning Protocols for Lithium‐Ion Electric Vehicle Batteries." Batteries & Supercaps 3, no. 9: 900-909.
Commercial lithium ion cells are now optimised for either high energy density or high power density. There is a trade off in cell design between the power and energy requirements. A tear down protocol has been developed, to investigate the internal components and cell engineering of nine cylindrical cells, with different power–energy ratios. The cells designed for high power applications used smaller particles of the active material in both the anodes and the cathodes. The cathodes for high power cells had higher porosities, but a similar trend was not observed for the anodes. In terms of cell design, the coat weights and areal capacities were lower for high power cells. The tag arrangements were the same in eight out of nine cells, with tags at each end of the anode, and one tag on the cathode. The thicknesses of the current collectors and separators were based on the best (thinnest) materials available when the cells were designed, rather than materials optimised for power or energy. To obtain high power, the resistance of each component is reduced as low as possible, and the lithium ion diffusion path lengths are minimised. This information illustrates the significant evolution of materials and components in lithium ion cells in recent years, and gives insight into designing higher power cells in the future.
Michael J. Lain; James Brandon; Emma Kendrick. Design Strategies for High Power vs. High Energy Lithium Ion Cells. Batteries 2019, 5, 64 .
AMA StyleMichael J. Lain, James Brandon, Emma Kendrick. Design Strategies for High Power vs. High Energy Lithium Ion Cells. Batteries. 2019; 5 (4):64.
Chicago/Turabian StyleMichael J. Lain; James Brandon; Emma Kendrick. 2019. "Design Strategies for High Power vs. High Energy Lithium Ion Cells." Batteries 5, no. 4: 64.
This work introduces a new method for inserting a Lithium reference electrode into commercially available 18650-type cells in order to obtain electrode potentials during cell operation. The proposed method is simple and requires limited equipment. Furthermore, electrical performance is significantly better and the cell capacity and resistance can be recorded for longer durations when compared to some of the previously used methods. Electrical performance of this new third electrode method is characterized and compared to 18650 cells with no reference electrode inserted. The capacity retention of the modified cell is more than 98% in the first 20 cycles. Harvested electrodes from a disassembled cell were also used to make coin cells that was proven to be a rather critical approach to get electrode potentials and capacities. This is an initial study that shows three-electrode performances of a commercial 18650-type cell, which suggests it could be used for understanding electrode behavior throughout a cell lifetime and for manufacturing instrumented cells.
Limhi Somerville; Stefania Ferrari; Michael J. Lain; Andrew McGordon; Paul Jennings; Rohit Bhagat. An In-Situ Reference Electrode Insertion Method for Commercial 18650-Type Cells. Batteries 2018, 4, 18 .
AMA StyleLimhi Somerville, Stefania Ferrari, Michael J. Lain, Andrew McGordon, Paul Jennings, Rohit Bhagat. An In-Situ Reference Electrode Insertion Method for Commercial 18650-Type Cells. Batteries. 2018; 4 (2):18.
Chicago/Turabian StyleLimhi Somerville; Stefania Ferrari; Michael J. Lain; Andrew McGordon; Paul Jennings; Rohit Bhagat. 2018. "An In-Situ Reference Electrode Insertion Method for Commercial 18650-Type Cells." Batteries 4, no. 2: 18.
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.
Melanie J. Loveridge; Guillaume Remy; Nadia Kourra; Ronny Genieser; Anup Barai; Mike J. Lain; Yue Guo; Mark Amor-Segan; Mark A. Williams; Tazdin Amietszajew; Mark Ellis; Rohit Bhagat; David Greenwood. Looking Deeper into the Galaxy (Note 7). Batteries 2018, 4, 3 .
AMA StyleMelanie J. Loveridge, Guillaume Remy, Nadia Kourra, Ronny Genieser, Anup Barai, Mike J. Lain, Yue Guo, Mark Amor-Segan, Mark A. Williams, Tazdin Amietszajew, Mark Ellis, Rohit Bhagat, David Greenwood. Looking Deeper into the Galaxy (Note 7). Batteries. 2018; 4 (1):3.
Chicago/Turabian StyleMelanie J. Loveridge; Guillaume Remy; Nadia Kourra; Ronny Genieser; Anup Barai; Mike J. Lain; Yue Guo; Mark Amor-Segan; Mark A. Williams; Tazdin Amietszajew; Mark Ellis; Rohit Bhagat; David Greenwood. 2018. "Looking Deeper into the Galaxy (Note 7)." Batteries 4, no. 1: 3.