That’s how experts call a deviation in the voltage of the battery that can limit the usability of the stored energy as well as the ability to determine the state of charge of the battery reliably.
Scientists at the Paul Scherrer Institute PSI, and the Toyota Central R&D Labs, Inc. in Japan have now however discovered a memory effect in a lithium-ion battery. This finding is particularly relevant for the use of lithium-ion batteries in the electric vehicle market. The work was published today in the scientific journal Nature Materials.Many of our everyday devices that get their energy supply from a battery, whilst not always being as “smart” as they are described in the adverts, often come equipped with a kind of memory. For example, a battery powered shaver or electric toothbrush that is recharged before the battery runs out, can later take revenge on the prudent user. The battery appears to remember that you have only taken part of its storage capacity – and eventually no longer supplies its full energy. Experts refer to this as a “memory effect“, which comes about because the working voltage of the battery drops over time because of incomplete charging-discharging cycles. This means that despite the battery still being discharged, the voltage it supplies is sometimes too low to drive the device in question. The memory effect therefore has two negative consequences: firstly, the usable capacity of the battery is reduced, and secondly the correlation between the voltage and the charge status is shifted, so the latter cannot be determined reliably on the basis of voltage.
According to Professor Petr Novak, Head of the Electrochemical Energy Storage Section at the PSI and co-author of the publication, the study disproves a long cherished misconception: ”Ours is the first study that has specifically looked for a memory effect in lithium-ion batteries. It had simply been assumed that no such effect would arise“. To acquire knowledge via research is often a fruitful mix of speculation and diligence: “Our finding results from a combination of critical investigation and careful observation. The effect is in fact tiny: the relative deviation in voltage is just a few parts per thousand. But the key was the idea of looking for it at all. Normal battery tests usually run deep, and not partial charging/discharging cycles. It thus took a flash of inspiration in order to ask what might happen during partial charging in the first place.For the future use of lithium-ion batteries in vehicles however, this recent discovery is not the final word. It is indeed absolutely possible that the effect could be detected and taken into account through clever adaptation of the software in battery management systems, Novak pointed out. Should that prove successful, the memory effect would not stand in the way of a reliable use of lithium-ion batteries in electric vehicles. So now, engineers face the challenge of finding the correct way of handling the peculiar memory of batteries.
Dagmar Baroke | idw
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20.09.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
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19.09.2017 | DOE/Lawrence Berkeley National Laboratory
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
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