̽��ֱ�� of Cambridge - Faraday Institution

What does it take to make a better battery?

lw355 — Tue, 01 Oct 2024 08:20:28 +0000

Cambridge researchers are working to solve one of technology’s biggest puzzles: how to build next-generation batteries that could power a green revolution.

Oxygen ‘holes’ could hold the key to higher performing EV batteries

sc604 — Wed, 19 Jul 2023 14:59:04 +0000

Nickel is already used in lithium-ion batteries, but increasing the proportion of nickel could significantly improve battery energy density, making them especially suitable for electric vehicles and grid-scale storage. However, practical applications for these materials have been limited by structural instability and the tendency to lose oxygen atoms, which cause battery degradation and failure.

̽��ֱ��researchers, led by the ̽��ֱ�� of Cambridge and the ̽��ֱ�� of Birmingham, found that ‘oxygen hole’ formation – where an oxygen ion loses an electron – plays a crucial role in the degradation of nickel-rich battery materials. These oxygen holes accelerate the release of oxygen that can further degrade the battery’s cathode, one of its two electrodes. Their results are reported in the journal Joule.

Using a set of computational techniques on UK regional supercomputers, the researchers examined the behaviour of nickel-rich cathodes as they charged. They found that during charging, the oxygen in the material undergoes changes while the nickel charge remains essentially unchanged.

“We found that the charge of the nickel ions remains around +2, regardless of whether it’s in its charged or discharged form,” said Professor Andrew J Morris, from the ̽��ֱ�� of Birmingham, who co-led the research. “At the same time, the charge of the oxygen varies from -1.5 to about -1.

“This is unusual, the conventional model assumes that the oxygen remains at -2 throughout charging, but these changes show that the oxygen is not very stable, and we have found a pathway for it to leave the nickel-rich cathode.”

̽��ֱ��researchers compared their calculations with experimental data and found that their results aligned well with what was observed. They proposed a mechanism for how oxygen is lost during this process, involving the combination of oxygen radicals to form a peroxide ion, which is then converted into oxygen gas, leaving vacancies in the material. This process releases energy and forms singlet oxygen, a highly reactive form of oxygen.

“Potentially, by adding compounds that shift the electrochemical reactions from oxygen more to the transition metals, especially at the surface of the battery materials, we can prevent the formation of singlet oxygen,” said first author Dr Annalena Genreith-Schriever from the Yusuf Hamied Department of Chemistry. “This will enhance the stability and longevity of these lithium-ion batteries, paving the way for more efficient and reliable energy storage systems.”

Lithium-ion batteries are widely used for various applications because of their high energy density and rechargeability, but challenges associated with the stability of cathode materials have hindered their overall performance and lifespan.

̽��ֱ��research was supported in part by the Faraday Institution, the UK’s flagship battery research programme.

Reference:
Annalena R Genreith-Schriever et al. ‘Oxygen Hole Formation Controls Stability in LiNiO2 Cathodes: DFT Studies of Oxygen Loss and Singlet Oxygen Formation in Li-Ion Batteries.’ Joule (2023). DOI: 10.1016/j.joule.2023.06.017

Adapted from a ̽��ֱ�� of Birmingham media release.

For more information on energy-related research in Cambridge, please visit Energy IRC, which brings together Cambridge’s research knowledge and expertise, in collaboration with global partners, to create solutions for a sustainable and resilient energy landscape for generations to come.

Scientists have made a breakthrough in understanding and overcoming the challenges associated with nickel-rich materials used in lithium-ion batteries.

This will enhance the stability and longevity of these lithium-ion batteries, paving the way for more efficient and reliable energy storage systems

Annalena Genreith-Schriever

Cavan images via Getty Images

View of woman's hand plugging in charging lead to her electric car

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Watching lithium in real time could improve performance of EV battery materials

sc604 — Fri, 14 Oct 2022 13:46:50 +0000

̽��ֱ��team, led by the ̽��ֱ�� of Cambridge, tracked the movement of lithium ions inside a promising new battery material in real time.

It had been assumed that the mechanism by which lithium ions are stored in battery materials is uniform across the individual active particles. However, the Cambridge-led team found that during the charge-discharge cycle, lithium storage is anything but uniform.

When the battery is near the end of its discharge cycle, the surfaces of the active particles become saturated by lithium while their cores are lithium deficient. This results in the loss of reusable lithium and a reduced capacity.

̽��ֱ��research, funded by the Faraday Institution, could help improve existing battery materials and could accelerate the development of next-generation batteries. ̽��ֱ��results are published in Joule.

Electrical vehicles (EVs) are vital in the transition to a zero-carbon economy. Most electric vehicles on the road today are powered by lithium-ion batteries, due in part to their high energy density.

However, as EV use becomes more widespread, the push for longer ranges and faster charging times means that current battery materials need to be improved, and new materials need to be identified.

Some of the most promising of these materials are state-of-the-art positive electrode materials known as layered lithium nickel-rich oxides, which are widely used in premium EVs. However, their working mechanisms, particularly lithium-ion transport under practical operating conditions, and how this is linked to their electrochemical performance, are not fully understood, so we cannot yet obtain maximum performance from these materials.

By tracking how light interacts with active particles during battery operation under a microscope, the researchers observed distinct differences in lithium storage during the charge-discharge cycle in nickel-rich manganese cobalt oxide (NMC).

“This is the first time that this non-uniformity in lithium storage has been directly observed in individual particles,” said co-first author Alice Merryweather, from Cambridge’s Yusuf Hamied Department of Chemistry. “Real time techniques like ours are essential to capture this while the battery is cycling.”

Combining the experimental observations with computer modelling, the researchers found that the non-uniformity originates from drastic changes to the rate of lithium-ion diffusion in NMC during the charge-discharge cycle. Specifically, lithium ions diffuse slowly in fully lithiated NMC particles, but the diffusion is significantly enhanced once some lithium ions are extracted from these particles.

“Our model provides insights into the range over which lithium-ion diffusion in NMC varies during the early stages of charging,” said co-first author Dr Shrinidhi Pandurangi from Cambridge’s Department of Engineering. “Our model predicted lithium distributions accurately and captured the degree of heterogeneity observed in experiments. These predictions are key to understanding other battery degradation mechanisms such as particle fracture.”

Importantly, the lithium heterogeneity seen at the end of discharge establishes one reason why nickel-rich cathode materials typically lose around ten percent of their capacity after the first charge-discharge cycle.

“This is significant, considering one industrial standard that is used to determine whether a battery should be retired or not is when it has lost 20 percent of its capacity,” said co-first author Dr Chao Xu, from ShanghaiTech ̽��ֱ��, who completed the research while based at Cambridge.

̽��ֱ��researchers are now seeking new approaches to increase the practical energy density and lifetime of these promising battery materials.

̽��ֱ��research was supported in part by the Engineering and Physical Sciences Research Council (EPSRC), part of UK Research and Innovation (UKRI). Alice Merryweather is jointly supervised by Professor Dame Clare Grey and Dr Akshay Rao, who are both co-authors on the current paper.

Reference:
Chao Xu et al. ‘Operando visualization of kinetically induced lithium heterogeneities in single-particle layered Ni-rich cathodes.’ Joule (2022). DOI: 10.1016/j.joule.2022.09.008

Researchers have found that the irregular movement of lithium ions in next-generation battery materials could be reducing their capacity and hindering their performance.

Andrew Roberts via Unsplash

Electric car charging

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Colour-changing magnifying glass gives clear view of infrared light

sc604 — Thu, 02 Dec 2021 19:00:00 +0000

Detecting light beyond the visible red range of our eyes is hard to do, because infrared light carries so little energy compared to ambient heat at room temperature. This obscures infrared light unless specialised detectors are chilled to very low temperatures, which is both expensive and energy-intensive.

Now researchers led by the ̽��ֱ�� of Cambridge have demonstrated a new concept in detecting infrared light, showing how to convert it into visible light, which is easily detected.

In collaboration with colleagues from the UK, Spain and Belgium, the team used a single layer of molecules to absorb the mid-infrared light inside their vibrating chemical bonds. These shaking molecules can donate their energy to visible light that they encounter, ‘upconverting’ it to emissions closer to the blue end of the spectrum, which can then be detected by modern visible-light cameras.

̽��ֱ��results, reported in the journal Science, open up new low-cost ways to sense contaminants, track cancers, check gas mixtures, and remotely sense the outer universe.

̽��ֱ��challenge faced by the researchers was to make sure the quaking molecules met the visible light quickly enough. “This meant we had to trap light really tightly around the molecules, by squeezing it into crevices surrounded by gold,” said first author Angelos Xomalis from Cambridge’s Cavendish Laboratory.

̽��ֱ��researchers devised a way to sandwich single molecular layers between a mirror and tiny chunks of gold, only possible with ‘meta-materials’ that can twist and squeeze light into volumes a billion times smaller than a human hair.

“Trapping these different colours of light at the same time was hard, but we wanted to find a way that wouldn’t be expensive and could easily produce practical devices,” said co-author Dr Rohit Chikkaraddy from the Cavendish Laboratory, who devised the experiments based on his simulations of light in these building blocks.

“It’s like listening to slow-rippling earthquake waves by colliding them with a violin string to get a high whistle that’s easy to hear, and without breaking the violin,” said Professor Jeremy Baumberg of the NanoPhotonics Centre at Cambridge’s Cavendish Laboratory, who led the research.

̽��ֱ��researchers emphasise that while it is early days, there are many ways to optimise the performance of these inexpensive molecular detectors, which then can access rich information in this window of the spectrum.

From astronomical observations of galactic structures to sensing human hormones or early signs of invasive cancers, many technologies can benefit from this new detector advance.

̽��ֱ��research was conducted by a team from the ̽��ֱ�� of Cambridge, KU Leuven, ̽��ֱ�� College London (UCL), the Faraday Institution, and Universitat Politècnica de València.

̽��ֱ��research is funded as part of a UK Engineering and Physical Sciences Research Council (EPSRC) investment in the Cambridge NanoPhotonics Centre, as well as the European Research Council (ERC), Trinity College Cambridge and KU Leuven.

Jeremy Baumberg is a Fellow of Jesus College, Cambridge.

Reference:
Angelos Xomalis et al. ‘Detecting mid-infrared light by molecular frequency upconversion with dual-wavelength hybrid nanoantennas’, Science (2021). DOI: 10.1126/science.abk2593

By trapping light into tiny crevices of gold, researchers have coaxed molecules to convert invisible infrared into visible light, creating new low-cost detectors for sensing.

It’s like listening to slow-rippling earthquake waves by colliding them with a violin string to get a high whistle that’s easy to hear, and without breaking the violin

Jeremy Baumberg

NanoPhotonics Cambridge /Ermanno Miele, Jeremy Baumberg

Nano-antennas convert invisible infrared into visible light

Yes

New insights into lithium-ion battery failure mechanism

sc604 — Mon, 24 Aug 2020 14:59:00 +0000

̽��ֱ��researchers, from the Universities of Cambridge and Liverpool, and the Diamond Light Source, have identified one of the reasons why state-of-the-art ‘nickel-rich’ battery materials become fatigued, and can no longer be fully charged after prolonged use.

Their results, reported in the journal Nature Materials, open the door to the development of new strategies to improve battery lifespans.

As part of efforts to combat climate change, many countries have announced ambitious plans to replace petrol or diesel vehicles with electric vehicles (EVs) by 2050 or earlier.

̽��ֱ��lithium-ion batteries used by EVs are likely to dominate the EV market for the foreseeable future, and nickel-rich lithium transition-metal oxides are the state-of-the-art choice for the positive electrode, or cathode, in these batteries.

Currently, most EV batteries contain significant amounts of cobalt in their cathode materials. However, cobalt can cause severe environmental damage, so researchers have been looking to replace it with nickel, which also offers higher practical capacities than cobalt. However, nickel-rich materials degrade much faster than existing technology and require additional study to be commercially viable for applications such as EVs.

“Unlike consumable electronics which typically have lifetimes of only a few years, vehicles are expected to last much longer and therefore it is essential to increase the lifetime of an EV battery,” said Dr Chao Xu from Cambridge’s Department of Chemistry, and the first author of the article. “That’s why a comprehensive, in-depth understanding of how they work and why they fail over a long time is crucial to improving their performance.”

To monitor the changes of the battery materials in real time over several months of battery testing, the researchers used laser technology to design a new coin cell, also known as button cell. “This design offers a new possibility of studying degradation mechanisms over a long period of cycling for many battery chemistries,” said Xu. During the study, the researchers found that a proportion of the cathode material becomes fatigued after repetitive charging and discharging of the cell, and the amount of the fatigued material increases as the cycling continues.

Xu and his colleagues dived deep into the structure of the material at the atomic scale to seek answers as to why such fatigue process occurs. “In order to fully function, battery materials need to expand and shrink as the lithium ions move in and out,” said Xu. “However, after prolonged use, we found that the atoms at the surface of the material had rearranged to form new structures that are no longer able to store energy.”

What’s worse is that these areas of reconstructed surface apparently act as stakes that pin the rest of the material in place and prevent it from the contraction which is required to reach the fully charged state. As a result, the lithium remains stuck in the lattice and this fatigued material can hold less charge.

With this knowledge, the researchers are now seeking effective countermeasures, such as protective coatings and functional electrolyte additives, to mitigate this degradation process and extend the lifetime of such batteries.

̽��ֱ��research, led by Professor Clare P Grey from the Chemistry Department at Cambridge, has been supported by the Faraday Institution Degradation Project.

Reference:
Chao Xu et al. ‘Bulk fatigue induced by surface reconstruction in layered Ni-rich cathodes for Li-ion batteries.’ Nature Materials (2020). DOI: 10.1038/s41563-020-0767-8

Researchers have identified a potential new degradation mechanism for electric vehicle batteries – a key step to designing effective methods to improve battery lifespan.

Yes

AI techniques used to improve battery health and safety

sc604 — Mon, 06 Apr 2020 10:58:14 +0000

̽��ֱ��researchers, from Cambridge and Newcastle Universities, have designed a new way to monitor batteries by sending electrical pulses into them and measuring the response. ̽��ֱ��measurements are then processed by a machine learning algorithm to predict the battery’s health and useful lifespan. Their method is non-invasive and is a simple add-on to any existing battery system. ̽��ֱ��results are reported in the journal Nature Communications.

Predicting the state of health and the remaining useful lifespan of lithium-ion batteries is one of the big problems limiting widespread adoption of electric vehicles: it’s also a familiar annoyance to mobile phone users. Over time, battery performance degrades via a complex network of subtle chemical processes. Individually, each of these processes doesn’t have much of an effect on battery performance, but collectively they can severely shorten a battery’s performance and lifespan.

Current methods for predicting battery health are based on tracking the current and voltage during battery charging and discharging. This misses important features that indicate battery health. Tracking the many processes that are happening within the battery requires new ways of probing batteries in action, as well as new algorithms that can detect subtle signals as they are charged and discharged.

"Safety and reliability are the most important design criteria as we develop batteries that can pack a lot of energy in a small space," said Dr Alpha Lee from Cambridge’s Cavendish Laboratory, who co-led the research. "By improving the software that monitors charging and discharging, and using data-driven software to control the charging process, I believe we can power a big improvement in battery performance."

̽��ֱ��researchers designed a way to monitor batteries by sending electrical pulses into it and measuring its response. A machine learning model is then used to discover specific features in the electrical response that are the tell-tale sign of battery aging. ̽��ֱ��researchers performed over 20,000 experimental measurements to train the model, the largest dataset of its kind. Importantly, the model learns how to distinguish important signals from irrelevant noise. Their method is non-invasive and is a simple add-on to any existing battery systems.

̽��ֱ��researchers also showed that the machine learning model can be interpreted to give hints about the physical mechanism of degradation. ̽��ֱ��model can inform which electrical signals are most correlated with aging, which in turn allows them to design specific experiments to probe why and how batteries degrade.

"Machine learning complements and augments physical understanding," said co-first author Dr Yunwei Zhang, also from the Cavendish Laboratory. " ̽��ֱ��interpretable signals identified by our machine learning model are a starting point for future theoretical and experimental studies."

̽��ֱ��researchers are now using their machine learning platform to understand degradation in different battery chemistries. They are also developing optimal battery charging protocols, powering by machine learning, to enable fast charging and minimise degradation.

This work was carried out with funding from the Faraday Institution. Dr Lee is also a Research Fellow at St Catharine’s College.

Reference:
Yunwei Zhang et al. ‘Identifying degradation patterns of lithium ion batteries from impedance spectroscopy using machine learning.’ Nature Communications (2020). DOI: 10.1038/s41467-020-15235-7

Researchers have designed a machine learning method that can predict battery health with 10x higher accuracy than current industry standard, which could aid in the development of safer and more reliable batteries for electric vehicles and consumer electronics.

Nordwood Themes via Unsplash

Person holding white Android phone

Yes

Cambridge to lead £11.9m research project to extend battery life for electric vehicles

Anonymous — Tue, 23 Jan 2018 23:30:00 +0000

̽��ֱ��funding for the four projects, totalling up to £42 million, was announced this week by the Faraday Institution, the UK’s independent national battery research institute. Cambridge will receive up to £11.9 million to research how to extend battery life for electric vehicles.

Led by Professor Clare Grey from the Department of Chemistry, the Cambridge-led project will examine how environmental and internal battery stresses (such as high temperatures, charging and discharging rates) damage electric vehicle (EV) batteries over time. Results will include the optimisation of battery materials and cells to extend battery life (and hence EV range), reduce battery costs, and enhance battery safety.

̽��ֱ��project includes nine university and 10 industry partners, including the ̽��ֱ�� of Glasgow, ̽��ֱ�� College London, Newcastle ̽��ֱ��, Imperial College London, ̽��ֱ�� of Strathclyde, ̽��ֱ�� of Manchester, ̽��ֱ�� of Southampton, ̽��ֱ�� of Liverpool and WMG, at the ̽��ֱ�� of Warwick.

̽��ֱ��other three projects to be funded by this week’s announcement are Battery system modelling, led by Imperial College London; Recycling and reuse, led by the ̽��ֱ�� of Birmingham; and Next-generation solid-state batteries, led by the ̽��ֱ�� of Oxford.

If successful, this research has the potential to radically increase the speed with which we are able to make the move to electric vehicles, as well as the speed with which we can decarbonise our energy supply, with obvious benefits to the environment.

“With 200,000 electric vehicles set to be on UK roads by the end of 2018 and worldwide sales growing by 45 percent in 2016, investment in car batteries is a massive opportunity for Britain and one that is estimated to be worth £5 billion by 2025,” said Business Minister Richard Harrington. “Government investment, through the Faraday Institution, in the projects announced today will deliver valuable research that will help us seize the economic opportunities presented by battery technology and our transition to a low-carbon economy.”

̽��ֱ��topics for the four projects were chosen in consultation with industry, who will partner closely with each of them. This unique collaboration will help to ensure that the research is producing findings and solutions that meet the needs of industry. In addition, industrial partners will contribute a total of £4.6 million in in-kind support to the following four projects:

“To deliver the much-needed improvement in air quality in our cities and achieve our aspiration for cleaner energy targets we need to shift to electric vehicles quickly,” said Peter B. Littlewood, founding executive chair of the Faraday Institution. “These research programmes will help the UK achieve this. To be impactful on increasing energy density, lowering cost, extending lifetime, and improving battery safety requires a substantial and focused effort in fundamental research. Through steady investment in basic research on specific societal challenges identified by industry and government, the UK will become a world-leading powerhouse in energy storage.”

Professor Philip Nelson, EPSRC’s Chief Executive, said: “There is an urgent imperative for us to increase the efficiency of energy storage as we move towards low carbon economies and attempt to switch to clean methods of energy production.

“ ̽��ֱ��Faraday Institution will bring leading academics in the field of battery development together with industry experts to explore novel application-inspired approaches that will address the challenges we face. ̽��ֱ��UK has an opportunity to accelerate the development of new products and techniques. EPSRC will be working with the Institution and the academic community to help it succeed and keep the UK a prosperous and productive nation.”

Originally published on the Faraday Institution website.

̽��ֱ�� ̽��ֱ�� of Cambridge is leading one of four government-funded projects into battery research, in order to accelerate the transition to electric vehicles and a low-carbon economy.

Chase Lewis

Tesla Supercharger

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes