Technical University of Berlin

An improved charging protocol might help lithium-ion batteries to last much longer. Charging with a high-frequency pulsed current reduces aging effects, an international team demonstrated. An improved charging protocol might help lithium-ion batteries to last much longer. Charging with a high-frequency pulsed current reduces ageing effects, an international team demonstrated. The study was led by Philipp Adelhelm (HZB and Humboldt University) in collaboration with teams from the Technical University of Berlin and Aalborg University in Denmark. Experiments at the X-ray source BESSY II were particularly revealing. Lithium-ion batteries are powerful, and they are used everywhere, from electric vehicles to electronic devices. However, their capacity gradually decreases over the course of hundreds of charging cycles. The best commercial lithium-ion batteries with electrodes made of so-called NMC532 (molecular formula: LiNi0.5Mn0.3Co0.2O2) and graphite have a service life of up to eight years. Batteries are usually charged with a constant current flow. But is this really the most favourable method? A new study by Prof Philipp Adelhelm's group at HZB and Humboldt-University Berlin answers this question clearly with no. The study in the journal Advanced Energy Materials analyses the effect of the charging protocol on the service time of the battery. Ageing effects analysed Part of the battery tests were carried out at Aalborg University. The batteries were either charged conventionally with constant current (CC) or with a new charging protocol with pulsed current (PC). Post-mortem analyses revealed clear differences after several charging cycles: In the CC samples, the solid electrolyte interface (SEI) at the anode was significantly thicker, which impaired the capacity. The team also found more cracks in the structure of the NMC532 and graphite electrodes, which also contributed to the loss of capacity. In contrast, PC-charging led to a thinner SEI interface and fewer structural changes in the electrode materials. Synchrotron experiments at BESSY II and PETRA III HZB researcher Dr Yaolin Xu then led the investigation into the lithium-ion cells at Humboldt University and BESSY II with operando Raman spectroscopy and dilatometry as well as X-ray absorption spectroscopy to analyse what happens during charging with different protocols. Supplementary experiments were carried out at the PETRA III synchrotron. "The pulsed current charging promotes the homogeneous distribution of the lithium ions in the graphite and thus reduces the mechanical stress and cracking of the graphite particles. This improves the structural stability of the graphite anode," he concludes. The pulsed charging also suppresses the structural changes of NMC532 cathode materials with less Ni-O bond length variation. The pulse current frequency is crucial However, the frequency of the pulsed current counts: High-frequency PC charging protocols with square-wave current extend the service life of commercial LIBs the most, with a doubled cycle life (with 80% capacity retention) achieved in this study. Co-author Prof. Dr Julia Kowal, an expert in electrical energy storage technology at TU Berlin, emphasises: "Pulsed charging could bring many advantages in terms of the stability of the electrode materials and the interfaces and significantly extend the service life of batteries."

The traveling salesman problem is considered a prime example of a combinatorial optimization problem. Now a team has shown that a certain class of such problems can actually be solved better and much faster with quantum computers than with conventional methods. The travelling salesman problem is considered a prime example of a combinatorial optimisation problem. Now a Berlin team led by theoretical physicist Prof. Dr. Jens Eisert of Freie Universität Berlin and HZB has shown that a certain class of such problems can actually be solved better and much faster with quantum computers than with conventional methods. Quantum computers use so-called qubits, which are not either zero or one as in conventional logic circuits, but can take on any value in between. These qubits are realised by highly cooled atoms, ions or superconducting circuits, and it is still physically very complex to build a quantum computer with many qubits. However, mathematical methods can already be used to explore what fault-tolerant quantum computers could achieve in the future. "There are a lot of myths about it, and sometimes a certain amount of hot air and hype. But we have approached the issue rigorously, using mathematical methods, and delivered solid results on the subject. Above all, we have clarified in what sense there can be any advantages at all," says Prof. Dr. Jens Eisert, who heads a joint research group at Freie Universität Berlin and Helmholtz-Zentrum Berlin. The well-known problem of the travelling salesman serves as a prime example: A traveller has to visit a number of cities and then return to his home town. Which is the shortest route? Although this problem is easy to understand, it becomes increasingly complex as the number of cities increases and computation time explodes. The travelling salesman problem stands for a group of optimisation problems that are of enormous economic importance, whether they involve railway networks, logistics or resource optimisation. Good enough solutions can be found using approximation methods. The team led by Jens Eisert and his colleague Jean-Pierre Seifert has now used purely analytical methods to evaluate how a quantum computer with qubits could solve this class of problems. A classic thought experiment with pen and paper and a lot of expertise. "We simply assume, regardless of the physical realisation, that there are enough qubits and look at the possibilities of performing computing operations with them," explains Vincent Ulitzsch, a PhD student at the Technical University of Berlin. In doing so, they unveiled similarities to a well-known problem in cryptography, i.e. the encryption of data. "We realised that we could use the Shor algorithm to solve a subclass of these optimisation problems," says Ulitzsch. This means that the computing time no longer "explodes" with the number of cities (exponential, 2N), but only increases polynomially, i.e. with Nx, where x is a constant. The solution obtained in this way is also qualitatively much better than the approximate solution using the conventional algorithm. "We have shown that for a specific but very important and practically relevant class of combinatorial optimisation problems, quantum computers have a fundamental advantage over classical computers for certain instances of the problem," says Eisert.

Technical University of Berlin researcher recognized for his innovative work in bioprocess engineering SANTA CLARA, Calif.--(BUSINESS WIRE)-- Agilent Technologies Inc. (NYSE: A) announced that Dr. Peter Neubauer has been selected to receive a prestigious Agilent Thought Leader Award. As Chair of Bioprocess Engineering at the Technical University of Berlin, Dr. Neubauer leads innovative research to identify new methods for more efficient bioprocess development, including genetic, cultivation, and analytical tools, with a particular focus on industrial-scale applications. Automation and high throughput are important for the real-time determination of critical quality attributes (CQAs), thus optimizing biotechnological applications. To this end, substantial resources are being directed toward developing process analytical technology (PAT) – a mechanism for designing, analyzing, and controlling pharmaceutical manufacturing processes by monitoring parameters that impact quality – to ultimately minimize public health risks. Dr. Neubauer’s work orchestrates hardware, software, automation, mathematical models, and AI to discover optimal conditions for PAT end-to-end workflows. Integrating intelligent technologies and automation into PAT solutions is a key factor for moving the pharmaceutical industry toward optimized bioprocesses that improve safety and reduce hands-on intervention. The Agilent Thought Leader Award will support his ongoing research into understanding and optimizing bioprocesses for difficult-to-express proteins and the development of scale-up/scale-down strategies. “We are truly grateful and excited that Agilent's award will open up the opportunity to incorporate two-dimensional liquid chromatography and mass spectrometry into our upcoming bioprocess laboratory. The use of such leading-edge instrumentation is a fundamental element in our journey towards achieving a higher level in automated bioprocess development,” said Dr. Neubauer who established and heads the KIWI-biolab as an International Future Laboratory for AI for Intelligent Integrated Biolaboratories. “Given our recent progress in seamlessly orchestrating all devices required in the process, ranging from extensive analyte-specific sample preparation to the management of big data, we feel ready to conquer this next logical step of integration.” “Agilent is pleased to grant this Thought Leader Award to Dr. Neubauer to support his scientific developments in the biopharma space,” said Sudharshana Seshadri, vice president and general manager of Agilent’s Liquid Chromatography, Mass Spectrometry, and Automation Divisions, and executive sponsor of the award. “His important work will help the pharmaceutical industry optimize their bioprocesses and accelerate improved healthcare worldwide.” The Agilent Thought Leader Award program promotes fundamental scientific advances by contributing financial support, products, and expertise to the research of influential thought leaders in the life sciences, diagnostics, and chemical analysis space. To learn more, visit the Agilent Thought Leader Award website. About Agilent Technologies Agilent Technologies Inc. (NYSE: A) is a global leader in analytical and clinical laboratory technologies, delivering insights and innovation that help our customers bring great science to life. Agilent’s full range of solutions includes instruments, software, services, and expertise that provide trusted answers to our customers' most challenging questions. The company generated revenue of $6.85 billion in fiscal 2022 and employs 18,000 people worldwide. Information about Agilent is available at . To receive the latest Agilent news, please subscribe to the Agilent Newsroom. Follow Agilent on LinkedIn and Facebook.