WMG, at the University of Warwick, has revealed its new EV battery recycling scale-up facility, the first of its kind in the UK.

The adoption of electric vehicles has created a huge demand for battery metals such as lithium, nickel and cobalt; and this will accelerate each year as electric vehicles replace conventional vehicles. UK-based OEMs pay hundreds to recycle end-of-life lithium-ion batteries that are then exported abroad for material recovery, with the material later repurchased. Recycling of batteries in the UK will provide a stable and sustainable supply of indigenously sourced metals that will be vital for the UK’s automotive needs.

Anwar Sattar, Lead Engineer at WMG, explains: ‘‘The UK has some of the best research organisations in the world, and this facility will now enable us, like our international peers, to take our innovations to the EV market direct.

“We can now carry out kilogramme scale research which will allow us to attain data that is much more valuable to the UK industry, allowing them to make informed decisions about issues such as material handling and separation, scalability, product quality and waste production.’’

Professor David Greenwood, CEO of the WMG Centre HVM Catapult and Director of Industrial Engagement adds: “Batteries are a key enabler to the use of zero carbon energy, and they are a great industrial opportunity for the UK. Making them uses significant quantities of valuable materials, so it is essential that they are safely collected and recycled at the end of their useful life – providing the material feedstock for future generations of batteries. Today’s processes recover as little as 50% of the mass of the battery, and require large quantities of energy and chemicals as inputs. This new facility at WMG will allow us to research new recovery techniques which are more effective, cleaner and cheaper to operate.”

The new recycling facility, funded by the High Value Manufacturing Catapult, is situated within the Advanced Materials Manufacturing Centre. It is equipped with state-of-the-art equipment such as a wet alkaline scrubber which will enable researchers to safely carry out experiments that are not possible elsewhere. It is designed to accommodate pilot scale recycling machinery including dryers, furnaces, separators, and various reactors for the chemical recovery of metals. The facility will also host a scaled-up version of WMG’s novel lithium recovery process which will be able to recover over 90% of the lithium in a battery at very high purities.

Various projects are already underway at the facility including an £8.9m project ‘Recycling of EV Cells from Obsolete Vehicles at Scale’ (RECOVAS). Supported by the Advanced Propulsion Centre, the project will create a circular supply chain for electric vehicle batteries in the UK.

Find out more about WMG’s battery research here: Energy (warwick.ac.uk)

A new partnership between Eatron TechnologiesLink opens in a new window and WMG has been formed for the COBRA (Cloud/Onboard Battery Remaining useful life Algorithm) project, thanks to the funding from the Faraday Battery ChallengeLink opens in a new window.

The COBRA project will create new algorithms which will estimate the Remaining Useful Life (RUL) in an Electric Vehicle (EV) battery, and could contribute to the UK becoming a supplier of the most advanced Battery Management Systems (BMS) in the world.

The innovation of project COBRA comes from combining advanced battery ageing models developed by WMG with Eatron Technologies' own machine-learning-based approach to Remaining Useful Life (RUL) estimation from existing internal R&D work.

The technology has been refined to a level of usability, reliability, and maturity that gives battery manufacturers and integrators the confidence required to enable mass adoption.

Undertaken by a team of highly experienced engineers with a track record of delivering state-of-the-art software and system solutions for electrification projects with the automotive sector, project COBRA will:

· Develop a unified physics and machine-learning-based approach for battery RUL estimation with high accuracy of over 90%.

· Integrate a developed solution in automotive-grade BMS hardware.

· Integrate a solution into cloud-based platforms for fleet operation services.

The funding from the Faraday Battery Challenge enables lead partner Eatron Technologies to put the UK on the map as a global leader in the design, development, and manufacture of batteries for electric vehicles. The COBRA project offers the opportunity to be first-to-market with an accurate RUL algorithm that can be implemented in a real-world BMS.

As part of project COBRA, Eatron Technologies is currently developing and integrating advanced battery diagnostics algorithms for its next generation of BMS and cloud-based battery analytics; it's expected that these will deliver significantly higher value both to battery manufacturers and integrators as well as electric vehicle Original Equipment Manufacturers (OEMs), UPS suppliers, and other providers of off-highway applications.

In terms of the usefulness of these technologies, the possibilities offered by project include: predicting the RUL of a lithium battery under real-world operating conditions, COBRA technology will work with both off-board fleet data analysis and on board vehicle data while integrating with the BMS and guide battery manufacturers and their cell suppliers.

All of this can be used to track and assess the real-life fleet performance of batteries during product validation and post-production phases. In wider terms, successful adoption of these new BMS features would ultimately also increase the value of the EVs and their uptake on UK roads`

As well as extending a batteries' first life by giving an accurate indication of a battery's remaining life, COBRA will also improve second-life applications by reducing the need for expensive testing, as well as increase the effective power of batteries by allowing the safe utilisation of a wider operating window.

Dr Dhammika Widanalage from WMG, University of Warwick comments:
“We are delighted to work with Eatron technologies on the COBRA project, and look forward to using our novel battery ageing technology to test out their algorithms in their battery management system.

“If their algorithms means consumers can get more out of their EV battery, then it’s possible more people may be inclined to buy one, therefore helping the UK pave the way to a cleaner greener zero-carbon future.”

After months of discussion with interested customers around the world, intelligent software provider Eatron Technologies found there exists a strong demand for the features that the COBRA project can offer in batteries for EVs. COBRA could contribute to the UK becoming a supplier of the most advanced Battery Management Systems (BMS) in the world, as well as contributing to an increased uptake of EVs which in turn will help nations around the globe to reach environmental targets over the coming decades.

"This funding has brought the project forward by 12 months, and there is huge demand from potential customers," said Dr Umut Genc, Managing Director, Eatron Technologies. "With the funding, we've been able to immediately hire additional software engineers as well as tapping into cutting-edge battery research from the team at WMG. Ultimately, grant funding this project de-risks the activities required to achieve feasibility of this highly innovative approach to RUL estimation.

Tony Harper, Challenge Director for Faraday Battery Challenge at UK Research and Innovation, said:
“Since 2017 the Faraday Battery Challenge has been supporting the UK’s battery companies to produce batteries that are more cost effective, more efficient, charge faster and can easily be recycled. This new round of funding has enabled us to support companies, like Eatron Technologies, across the battery supply chain and build on the UK’s world class research and innovation.”

EVs on UK roads are set to see rapid growth, with 1.8 million expected to be sold in 2030, or 64% of total car sales, according to the Faraday Institution. The accompanying acceleration in battery manufacturing will drive a substantial increase in second-life applications, while the supply for stationary applications could excess 200 gigawatt-hours per year by 2030.

This rapid adoption of EVs around the world will increase global demand for BMSs over the coming years. Eatron Technologies is proud to be seen as a forerunner in BMS technology by the Faraday Institute and hopes that project COBRA plays an important role in the global fight for the environment by making EVs more practical for fleet operators and drivers around the world.

MOU signed between Johnson Matthey, Faraday Institution, Britishvolt, Oxford University, UK Battery Industrialisation Centre, Emerson & Renwick and University of Warwick

HARWELL, UK (19 August 2021) A consortium of seven UK-based organisations has signed a memorandum of understanding to combine ambitions to develop world-leading prototype solid-state battery technology, targeting automotive applications.

Solid-state batteries offer significant potential advantages over conventional lithium-ion batteries and could be transformational in meeting the UK’s net zero commitments through the electrification of transport. The successful outcome of the collaboration would be to harness and industrialise UK academic capability to produce cells using highly scalable manufacturing techniques that leapfrog the cost-effectiveness and performance achieved elsewhere.

The consortium comprises the following world-leading organisations in battery research, development and manufacturing:

· Faraday Institution – the UK’s independent institute for electrochemical energy storage research, which has led the consortium’s formation and will lead its development.

· Britishvolt – the UK-based Gigaplant developer, with a site in NE England.

· E+R (Emerson & Renwick) – a world leading designer of manufacturing equipment.

· Johnson Matthey – a global leader in sustainable technologies and the UK’s leading battery materials business.

· Oxford University – that leads the Faraday Institution’s solid-state battery project (SOLBAT) and provides the necessary scientific understanding to the consortium.

· UK Battery Industrialisation Centre – the pioneering battery manufacturing development facility to enable UK battery manufacturing scale-up and facilitate upskilling in the battery sector.

· WMG, University of Warwick – leaders in battery R&D and initial scale-up capability, as well as academic and apprenticeship skills development.

The preliminary design for a prototyping facility has been developed. Sources of funding are currently being sought.

Minister for Investment Lord Grimstone said: “Collaboration between industry, government and our world-leading academic institutions is putting the UK at the forefront of global efforts to develop innovative automotive technologies, such as solid-state batteries.

“It is the work of our internationally-renowned research and development base, like those brought together by this consortium, that will give us the tools needed to forge a strong and sustainable future for the automotive sector and increase our contribution to combatting climate change.”

“I am delighted to be able to announce the formation of this unique consortium for the advancement of solid-state battery prototyping that includes leading UK-based organisations at many stages in the value chain,” said Professor Pam Thomas, CEO of Faraday Institution. “Our leadership in this venture signals a move towards a role that the Faraday Institution will increasingly play as a trusted convener of significant partnerships between UK industry and academia as a route to commercialise breakthrough science emerging from our research programmes to maximise UK economic value.”

Solid-state batteries (SSBs) offer significant potential advantages over existing lithium-ion battery technologies, including the ability to hold more charge for a given volume (leading to increased electric vehicle (EV) range) and reduced costs of safety-management. Early deployment of SSBs is likely to be in consumer electronics, niche automotive applications and unmanned aerospace, before being used in broader EV markets. The Faraday Institution forecasts that, in 2030, SSBs are likely to take a 7% share of the global consumer electronics battery market and a 4% share of the EV battery market[1]. Global SSB revenues from sales to EV manufacturers are expected to reach $8 billion by 2030[2] and then grow rapidly to 2040 and 2050 when the market is expected to become extensive.

However, there are fundamental scientific challenges that need to be addressed before high power SSBs with commercially relevant performance can be realised. The Faraday Institution’s SOLBAT project has made considerable progress in addressing these challenges over the last three years.

The construction of the one-of-a-kind facility being developed by the collaboration will enable SSB technology to emerge from UK university laboratories. It will allow larger cells to be produced using scalable manufacturing techniques that will be improved iteratively through deep investigation of the causes of problems that emerge during manufacture and testing of prototype batteries. This will leverage the collective knowledge of Faraday Institution SSB researchers and the industrial partners.

Christian Gunther, CEO, Battery Materials at Johnson Matthey comments, “The realisation of a prototype solid-state battery cell will be a great achievement for the UK battery industry, and this consortium will be a critical enabler for delivering this milestone. Delivering enhanced range and safety over traditional lithium-ion battery technologies will be a key driver for battery electric vehicle adoption, supporting the transition to a net zero future.”

Dr Allan Paterson, Chief Technology Officer, Britishvolt comments, “Solid-state is the holy grail of battery solutions. Solid-state batteries have the potential to increase energy density significantly over battery technology available today and could dramatically, and positively, change the world of electric vehicles. Britishvolt will be at the forefront of commercialising this step change over the coming years. This collaboration, which includes major global industrial leaders such as Johnson Matthey and academic leadership from University of Oxford, underscores another key objective in our technology roadmap – home grown intellectual property.”

Professor Peter Bruce, Principal Investigator of SOLBAT, comments: “It’s fantastic to see the culmination of combined UK academic strength in solid-state battery research come to fruition. I’m proud that the work of the Faraday Institution SOLBAT project, led by Oxford University, will make a significant contribution to the UK’s green energy revolution.”

Ian Whiting, Commercial Director at UKBIC added: “Our newly opened national battery manufacturing scale up facility is already contracted to scale new cells and battery packs by companies basing their manufacturing centres in the UK. It’s a really exciting time for this fast-growing industry. We’re scaling technologies that will be the core products of the UK’s emergent Gigafactories. But we need to think even further ahead and solid-state battery technology is going to be a big part of that. This collaboration is what is needed to give the UK the edge it needs in creating a centre of excellence for solid-state batteries and we’re excited to be part of it. The bringing together of academic and industrial know how in this space is key to unlocking Britain’s electrified potential.”

David Greenwood, Professor of Advanced Propulsion Systems, and CEO of WMG High Value Manufacturing Catapult comments: “Early forms of solid-state battery are already around us, but we have yet to see solutions which are both mass-manufacturable and meet the performance and cost targets for future transport applications. There remains huge opportunity for innovation in this space, and this initiative will provide the route for the UK to fast-track candidate technologies to industrialisation.”

Andrew C Jack, Sales Director, E&R Group comments, “E&R Group are delighted to be contributing our world renowned engineering expertise working in partnership Faraday and the wider consortium on this exciting development for next generation battery production for the UK.

For more information on the Faraday Institution, visit www.faraday.ac.uk and follow @FaradayInst on twitter.

WMG Associate Professor Dr Mel Loveridge, and Principal Engineer Martin Dowson, have authored a special Faraday Insight entitled “Why Batteries Fail and How to Improve Them: Understanding Degradation to Advance Lithium-Ion Battery Performance,” a key consideration as we transition to a fully electric future.

It is part of a collection, of pieces from leading UK battery experts, published by the Faraday Institution. The Faraday Insights are evidence-based assessments of the market, economics, commercial potential, and capabilities for energy storage technologies. The insights are concise briefings that aim to help bridge knowledge gaps across industry, academia, and government.

The briefing addresses key requirements in lifetime, performance and safety needed for LIBs to continue to lead electrification in multiple sectors, and explains why, to achieve this researchers need to better understand – and find ways to mitigate – the many causes of battery degradation.

Read the Insight here: www.faraday.ac.uk/get/insight-10/

Read more about WMG’s Electrochemical Engineering research here: Electrochemical Materials (warwick.ac.uk)

• By 2030 only EV’s will be in production, meaning manufacturers are racing to create a high-energy battery that’s affordable and charges efficiently, but conventional battery cathodes cannot reach the targets of 500Wh/Kg
• Lithium-excess cathodes offer the ability to reach 500Wh/Kg but unlocking their full capacity means understanding how they can store charge at high voltages
• A new X-ray study lead by WMG, University of Warwick has resolved how the metals and oxygen facilitate the charge storage at high voltages

High energy storage batteries for EVs need high capacity battery cathodes. New lithium-excess magnesium-rich cathodes are expected to replace existing nickel-rich cathodes but understanding how the magnesium and oxygen accommodate charge storage at high voltages is critical for their successful adaption. Research led by WMG, University of Warwick in collaboration with U.S. researchers employed a range of X-ray studies to determine that the oxygen ions are facilitating the charge storage rather than the magnesium ions.

Electric vehicles will one day dominate UK roads and are critical for eliminating CO2 emissions, but a major issue car manufacturers face is how to make an affordable long-lasting energy-dense battery that can be charged quickly and efficiently. There is therefore a race to make EV batteries with an energy storage target of 500 Wh/Kg, but these targets are not possible without changing to new cathode materials.

Although progress has continued over the last 10 years to push the performance of state-of-the-art nickel-rich cathodes for EV, the material is unable to provide the energy density needed. To increase the capacity more lithium needs to be used, which means going beyond the ability of nickel to store electron charge.

Lithium-excess magnesium-rich cathodes offer sufficient energy density but to reach ultimately reach energy storage targets of 500Wh/Kg we need to understand how the electron charge is stored in the material. Simply put, is the electron charge stored on the magnesium or oxygen sites.

In the paper, ‘Whither Mn Oxidation in Mn-Rich Alkali-Excess Cathodes?’, published in the Journal ACS Energy Letters today the 17th of February, researchers from WMG, University of Warwick have overcome a significant milestone in understanding of charge storage in lithium-excess magnesium-rich cathodes.

Li-excess compounds that involve conventional and non-conventional redox, conventional refers to metal ions changing their electron density. Reversibly changing the electron density on the oxygen (or oxygen redox) without it forming O2 gas is unconventional redox. Various computational models exist in the literature describing different mechanisms involving both, but careful x-ray studies performed while the battery is cycling (operando) are ultimately required to validate these models.

Researchers between the UK and US, led by WMG at the University of Warwick, performed operando x-ray studies to precisely quantify magnesium and oxygen species at high voltages. They demonstrated how x-ray beams could irreversibly drive highly oxidized magnesium (Mn7+) to trapped O2 gas irreversibly in other materials.

However, by performing careful operando x-ray studies that circumvented beam damage and observe only trace amounts of Mn7+ forming upon charging in Li-excess cathodes during battery cycling.

Professor Louis Piper, from WMG, University of Warwick explains:
“We have ultimately resolved that oxygen rather than metal redox is driving the higher capacity, which means we can now design better strategies to improve cycling and performance for this class of materials.”

ENDS

17 FEBRUARY 2021

NOTES TO EDITORS

High-res images available at:

https://warwick.ac.uk/services/communications/medialibrary/images/february_2021/operando_x-ray_louis_piper.jpg
Caption: Photo of the operando x-ray studies being performed at a Synchrotron facility.
Credit: WMG, University of Warwick

Paper available to view at: https://pubs.acs.org/doi/10.1021/acsenergylett.0c02418

For further information please contact:

Alice Scott
Media Relations Manager – Science
University of Warwick
Tel: +44 (0) 7920 531 221
E-mail: alice.j.scott@warwick.ac.uk

Researchers in WMG at the University of Warwick, in collaboration with Imperial College London, have found a way to enhance hybrid flow batteries and their commercial use. The new approach can store electricity in these batteries for very long durations for about a fifth the price of current technologies, with minimal location restraints and zero emissions.

The researchers enhanced three hybrid flow cells using nitrogen doped graphene (exposed to nitrogen plasma) in a binder-free electrophoresis technique (EPD)

Wind and solar power are increasingly popular sources for renewable energy. Unfortunately, intermittency issues keep them from connecting widely to the National grid. One potential solution to this problem involves in the deployment of long-duration battery technology, such as the redox flow battery. Despite its great promise the current costs of this system are a key determining factor to real-world adoption. An affordable grid battery should cost £75/kWh, according to the US Department of Energy. Lithium-ion batteries, which lead the charge for grid storage, cost about £130/kWh.

Now WMG researchers have found a way of enhancing hybrid flow batteries or regenerative fuel cell (RFC) technology that could store electricity for very long durations for about one-fifth the cost of current storage technologies, with flexibility in siting and with minimal environmental impact. The technology combines carbon-based electrodes with economically sourced electrolytes, (manganese or sulphur, which are abundant chemicals in the planet) by means of a simple and yet highly effective electrophoretic deposition of nano-carbon additives (nitrogen-doped graphene) that enhance the electrode durability and performance significantly in highly acidic or alkaline environments.

The researchers have published their findings in a paper entitled, ‘Hybrid Redox Flow Cells with Enhanced Electrochemical Performance via Binderless and Electrophoretically Deposited Nitrogen-Doped Graphene on Carbon Paper Electrodes’ in the December 2020 edition of the journal ACS Applied Materials & Interfaces.

Dr Barun Chakrabarti, a Research Fellow in WMG at the University of Warwick and one of the lead authors on the paper said:

“This EPD technique is not only simple but also improves the efficiencies of three different economical hybrid flow batteries thereby increasing their potential for widespread commercial adoption for grid-scale energy storage.”

The hybrid flow battery’s total chemical cost is about 1/30th the cost of competing batteries, such as lithium-ion systems. Scaled-up technologies may be used to store electricity from wind or solar power, for multiple days to entire seasons, for about £15 to £20 per kilowatt hour. These batteries are also extremely useful for grid-scale load levelling applications as their design is very flexible due to their unique feature of sizing their power independently of their energy.

The energy density of a hybrid flow battery, especially the polysulphide/air system (S-Air), is 500 times higher than pumped hydroelectric storage. It is also so much more compact and can be placed near any renewable generation.

ENDS

22 JANUARY 2021

Notes for Editors

High-res image available at:
https://warwick.ac.uk/services/communications/medialibrary/images/january_2021/barun_release_image.jpg
Caption: A Binder-Free Horizontal Electrophoretic Deposition (EPD) Process Is Used to Activate Commercial Carbon Paper Electrodes Using Nitrogen-Doped Graphene
Credit: WMG, University of Warwick

Full list of researchers: Co-investigators with Dr Chakrabarti at the WMG Energy Innovation Centre at the University of Warwick are: Evangelos Kalamaras (Project Engineer, Battery Testing) and Professor Jon Low (Associate Professor, Electrochemical Engineering). Co-investigators from Imperial include Anthony Kucernak and Nigel Brandon.

The full paper with all author details can be found here: Hybrid Redox Flow Cells with Enhanced Electrochemical Performance via Binderless and Electrophoretically Deposited Nitrogen-Doped Graphene on Carbon Paper Electrodes

Background history to this area of research
Development of the EPD technology began in 2013, when Professor Low joined WMG as an Assistant Professor and researched industrial Lithium-ion battery manufacturing processes. EPD involves the migration of electrically charged particles through a fluid that is under the influence of an electric field generated by applying the right potential.

Although EPD is an industrially adopted process such as for depositing industrial coatings onto conductive substrates, its mass-scale adoption for energy storage applications has only recently seen some success. Supported by EPSRC’s First Grant (EP/P026818/1, https://gtr.ukri.org/projects?ref=EP%2FP026818%2F1) and Industrial Strategy Challenge Fund on battery and supercapacitor manufacturing (EP/R023034/1, https://gtr.ukri.org/projects?ref=EP%2FR023034%2F1), Low’s research team have developed EPD for preparing lithium-ion battery electrodes that meet industrial standards for thickness and mass loadings and published their finding in ‘Batteries and Supercaps’ (https://chemistry-europe.onlinelibrary.wiley.com/doi/full/10.1002/batt.201900017). They have also produced carbon electrodes with nanomaterials for improving the practical performance of vanadium-based flow batteries using deep eutectic solvent electrolytes, and published their finding in ‘Batteries’ (https://www.mdpi.com/2313-0105/6/3/38).

FOR FURTHER INFORMATION PLEASE CONTACT:

Alice Scott
Media Relations Manager – Science
University of Warwick
Tel: +44 (0) 7920 531 221
E-mail: alice.j.scott@warwick.ac.uk

As the inevitable growth of transport electrification continues, the types of batteries that will be used in such vehicles, their charging parameters, infrastructure and timeframes are key considerations that will speed up the transition to electrification.

In the paper, ‘Determining the Limits and Effects of High-Rate Cycling on Lithium Iron Phosphate Cylindrical Cells’ published in and on the cover of the Journal Batteries, researchers from WMG, University of Warwick investigated the impacts on battery cell ageing from high current operation using commercial cells.

They used two tests to establish the maximum current limits before cell failure and applied this maximum current until cell failure. Testing was performed to determine how far cycling parameters could progress beyond the manufacturer’s recommendations.

During testing, current fluxes were increased up to 100 C cycling conditions. Charge and discharge current capabilities were possible at magnitudes of 1.38 and 4.4 times, respectively, more than that specified by the manufacturers’ claims. This increased current was applied for 500 charge-discharge.

However, the application of these currents resulted in a rapid decrease in capacity in the first 60 cycles as well as an increase in resistance. Furthermore, the application of such currents resulted in the increase of cell temperature, during both charge and discharge with natural convection during the rest step cooling the cell. Batteries operate in an optimum temperature range, and any deviations outside this can cause components and chemicals to start decomposing inside them.

They also identified deformation of the “jelly roll” (coiled electrodes and separator) with formation of lithium plating from testing and ageing. These deformations emanate from the centre of the cell in an axial direction towards the outside of the cell, suggesting the core of the cell was the hottest.

Lead Engineer, Justin Holloway, from WMG, University of Warwick comments:

“The testing showed there is a window for operating batteries above manufacturer stated current limits, however, whilst maintaining manufacturer stated voltage limits. We need to ensure that batteries operate in as the safest manner possible, and for an appropriate practical lifetime, which is why the manufacturers have these limits.

“We also identified thermal fatigue as the driving mechanism for jelly roll deformation. With each cycle of charge and discharge, the cell experienced thermal stresses causing deformation of its components. These deformations grew progressively with cycle number, while the jelly roll was constrained mechanically by the rigid outer can and centre pin.

“If convection cooling could be applied to the centre of the cell where the cell was the hottest, these deformations could be mitigated and controlled, allowing the cell to maintain capacity and resistance criteria for longer.”

The researchers would like to thank all involved in this work, including WMG’s High Value Manufacturing Catapult and The Faraday Institution. WMG’s Battery Forensic Group, led by Dr Mel Loveridge is keen to engage with industry and academia alike to grow advances in understanding new materials, battery performance and degradation modes.

ENDS

14 DECEMBER 2020

NOTES TO EDITORS

High-res images available at:
https://warwick.ac.uk/services/communications/medialibrary/images/december_2020/justin_holloway.jpg
Caption: Justin Holloway, from WMG, University of Warwick
Credit: WMG, University of Warwick

Paper available to view at: https://www.mdpi.com/2313-0105/6/4/57/pdf

For further information please contact:

Alice Scott
Media Relations Manager – Science
University of Warwick
Tel: +44 (0) 7920 531 221
E-mail: alice.j.scott@warwick.ac.uk

• The issue of how long a battery pack will remain in useful operation, to guarantee a warranty for an electric vehicle battery, is a challenge faced by most car manufacturers, as they haven’t been around long enough for them to know their full lifetime
• Working as part of an APC6 funded project, WMG at the University of Warwick developed a battery model capable of forecasting the battery health for realistic usage cases
• Researchers at WMG experimentally tested the batteries for several usage cases and the model predicted the evolution of battery health with 98% accuracy

Extensive research, carried out by researchers from WMG, University of Warwick included characterisation, performance, safety and degradation testing of an EV battery, with degradation being the key focus to understand the impact on battery pack warranty.

To predict the degradation of the battery capacity researchers had to build a complex battery model, incorporating the key physics that causes batteries to age. The model was capable to predict scenarios under which a battery health will gradually fade and fulfil the warranty requirements and scenarios where the battery health will suddenly decrease after a certain usage duration.

Knowing when a battery’s health, can suddenly decrease, known as the ‘knee-point’ effect is a hotly studied problem among lithium-ion battery researchers. Researchers found that, for the particular battery investigated, by avoiding deep discharges and reducing the number of fast-charging a week, enabled the battery to perform and last the expected lifetime of the battery pack.

The aged cells were subsequently disassembled and examined for failure evidences. Fully discharging the battery at different rates demonstrated a thin film to deposit on the electrode and deform the electrode causing the active material in the batteries to delaminate. These effects can bring about a sudden reduction in the battery health.

Dr Dhammika Widanalage, from WMG, University of Warwick comments:

“We worked with the project partners to understand the needs of the battery ageing model and the usage scenarios. Using the data from our laboratories, we were then able to calibrate our model and also predict the voltage response and capacity fade of the battery under new usage cases with a very high accuracy of around 98%.”

It is common knowledge in battery manufacturing that many cathode materials are moisture sensitive. However, as the popularity of high nickel-based battery components increases, researchers from WMG, University of Warwick have found that the drier the conditions that these cathodes are stored and processed in, then significant improvement in performance of the battery is gained.

High-Ni (Nickel) batteries are becoming increasingly popular worldwide, with more automotive companies investigating the use of high-Ni batteries for electric vehicles. However, high-Ni cathode materials are prone to reactivity and instability is exposed to humidity, therefore how they are stored in order to offer the best performance is crucial.

In the paper, ‘The effects of Ambient Storage Conditions on the Structural and Electrochemical Properties of NMC-811 Cathodes for Li-ion batteries,’ published in the journal Electrochimica Acta, researchers from WMG, University of Warwick propose the best way to store high-nickel cathodes in order to mitigate premature degradation.

Researchers exposed NMC-811 (high-Ni cathode material) to different temperatures and humidities, then measured the material’s performance and degradation in a battery over a 28 day period, analysing them using a combination of physical, chemical and electrochemical testing. This included high-resolution microscopy to identify the morphological and chemical changes that occurred at the micron and sub-micron scale during the batteries charging and discharging.

The storage conditions included vacuum oven-dried, as exposed (to humidity) and a control measure. Researchers looked for surface impurities, which include carbonates and H₂O, and found there were three processes that can be responsible for impurities, including:

1. Residual impurities emanating from unreacted precursors during synthesis

2. Higher equilibrium coverage of surface carbonates/hydroxides (present to stabilise the surface of Ni-rich materials after the synthesis process)

3. Impurities formed during ambient storage time

They found that in all conditions, (oven dried and as-exposed) showed inferior first discharged specific capacity and cycling performance, compared to the control. However the as-exposed measure showed that after 28 days of ambient moisture exposure the H2O and CO2 react with the Li+ ions in the battery cell, resulting in the formation of lithium carbonate and hydroxide species.

The formation of carbonates and oxides on the surface of NMC-811 contribute to the loss of the electrochemical performance during ageing of the materials, due to the inferior ionic and electronic conductivity, as well as the electrical isolation of the active particles. This means that they can no longer reversibly store lithium ions to convey “charge”. SEM analysis confirmed the inter-granular porosity and micro-cracks on these aggregate particles, following the 28 days of ambient exposure.

They can therefore conclude that the driest conditions, at dew points of around -45 ^oC, are the best for storing AND processing the materials, in order to then produce the best battery performance. Humidity conditions and exposure at junctions along the manufacturing process will cause the materials and components to experience; this results in shorter battery lifespan.

Dr Mel Loveridge from WMG at the University of Warwick comments:

“Whilst moisture is well known to be problematic here, we set about to determine the optimal storage conditions that are required to mitigate unwanted, premature degradation in battery performance. Such measures are critical to improve processing capability, and ultimately maintain performance levels. This is also of relevance to other Ni-rich systems e.g. NCA materials.”

Professor Louis Piper from WMG at the University of Warwick adds:
“Considerable global research effort will continue to focus on these materials, including how to protect their surfaces to eliminate risks of parasitic reactions prior to incorporation into electrodes. In the UK, leading research by the Faraday Institution has a project consortium entirely devoted to unravelling the degradation mechanisms of such industry-relevant materials.”

ENDS

18 NOVEMBER 2020

NOTES TO EDITORS

High-res images available at:
https://warwick.ac.uk/services/communications/medialibrary/images/october_2020/the_effects_of_ambient_air_storage_on_the_surface_stability_of_nmc-811.jpg

(1) Caption: The effects of ambient air storage on the surface of NMC-811

Credit: WMG, University of Warwick

 https://warwick.ac.uk/services/communications/medialibrary/images/october_2020/post-mortem_nmc811_particle.jpg
(2) Caption: a-b) Post-mortem NMC811 particle, with no prior exposure to moist air, analysed by FIB-SIMS, targeting Lithium detection. c-d) Post-mortem NMC811 particle, after 28 days exposure to moist air, analysed by FIB-SIMS, targeting Lithium detection.
Credit: WMG, University of Warwick

https://warwick.ac.uk/services/communications/medialibrary/images/october_2020/schematic.jpg
(3) Caption: Schematic illustration of particle breakdown during charge-discharge of a battery
Credit: WMG, University of Warwick

Paper available to view at: https://www.sciencedirect.com/science/article/pii/S0013468620317515?via%3Dihub

• Lithium (Li)-ion batteries (LIBs) are the electrochemical energy storage systems of choice for a wide variety of applications, however other types of emerging battery technologies are currently on the path to share their dominant position.
• Among them Sodium (Na)-ion batteries (NIBs) have great potential to represent the next generation low cost and environmentally friendly energy storage solution. The diverse key performance indicators required by different applications and the market diversification is the driving force pushing the Na-ion technology closer to the market.
• A team of scientists including WMG at the University of Warwick combined their knowledge and expertise to assess the current status of the Na-ion technology from materials to cell development, offering a realistic comparison of the key performance indicators for NBs and LIBs.

LIBs play a primary role in the transition to a low carbon economy. However, as the market rapidly expands, the environmental and social challenges associated with the mass production of LIBs is triggering large attention toward the search for alternative energy storage solutions based on materials that can be sourced in a sustainable and responsible way. In this scenario, NIBs represent an alternative low cost, sustainable and more environmentally friendly energy storage technology.

In the paper ‘Challenges of today for Na-based batteries of the future: from materials to cell metrics,' published on the 18^th of September 2020 in the Journal of Power Sources, a large team of Na-ion technology expert scientists, led by WMG, at the University of Warwick (UK) analyse the prospect of NIBs taking a spot in the energy storage market. The paper also includes researchers from: Helmholtz Institute Ulm (Germany), College de France (France), Humboldt University Berlin (Germany), Institute for Energy technology (Norway), Université de Picardie Jules Verne (France), University of Bordeaux (France) and CIC energiGUNE (Spain).

Na- based batteries offer a combination of attractive properties. They are low cost, use sustainable precursors and have secure raw material supplies. In addition, they are considered as a drop-in technology which could benefit from the already existing Li-ion batteries manufacturing facilities.

As Li-based systems, Na-based batteries come in different forms, such as Na-ion, Na-all-solid-state-batteries, NaO₂ and Na/S. While the last ones are seen as disruptive future technologies, the Na-ion technology represent an attractive technology almost ready to challenge the Li-ion batteries in specific applications.

Performance metrics are of utmost importance for the SIB technology to ensure a competitive cost per Wh and find a place in the market. In this work, the most promising electrode materials and electrolyte systems have been reviewed and performance metrics from the academic literature have been used to extrapolate full sodium ion cells performance indicators.

Authors indicate that with the ongoing development, the present best materials available for Na-ion cells should allow approaching the energy density of the present generation of Li-ion commercial cells. One of the most important application field for the developed sodium-ion battery prototypes is certainly stationary energy storage systems, where cost and cycle life represent two fundamental parameters. “In this field sodium-ion batteries have the potential to dominate the future market representing the most promising system to fill the gap between energy production and utilization by securing energy supply. However high-power applications in the electrified automotive field are a potential niche field application for NIBs” says Dr Ivana Hasa, Assistant Professor at WMG.

Further technological improvements are needed to increase the performance especially in terms of energy density. Extremely encouraging results have been achieved for the Na-ion technology in a very short time when compared to the Li-ion technology. Technological improvement will be achieved by cell component fabrication/assembly optimization, as occurred in the last thirty years for the LIB technology.

Dr Ivana Hasa, from WMG, University of Warwick comments:

“From an applied research point of view, the future research efforts should be devoted on fundamental research, materials discovery and understanding of the thermodynamic and kinetic processes governing the chemistry of these systems. In addition, the investigation of upscaled Na-ion batteries is of primary importance to obtain realistic data to benchmark the progress of the technology as well as the adoption of a common reporting methodology in the scientific community enabling a fair comparison among performance results.”