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Trending Papers in materials science

Scientists create a highly deformable, non-cuttable material
From Paper: Non-cuttable material created through local resonance and strain rate effects
  • This study reports the creation of a new architected material, which is both highly deformable and ultra‐resistant to dynamic point loads
Submitted by Patrick Joyce
Batteries for self-driving cars
From Paper: Trade-offs between automation and light vehicle electrification
Weight, computing load, sensor load and possibly higher drag may increase the energy use of automated electric vehicles relative to human-driven electric vehicles, although this increase may be offset by smoother driving. Here, we use a vehicle dynamics model to evaluate the trade-off between automation and electric vehicle range and battery longevity. We find that automation will likely reduce electric vehicle range by 5–10% for suburban driving and by 10–15% for city driving. The effect on range is strongly influenced by sensor drag for suburban driving and computing loads for city driving. The impact of automation on battery longevity is negligible. While some commentators have suggested that the power and energy requirements of automation mean that the first automated vehicles will be gas–electric hybrids, our results suggest that this need not be the case if automakers can implement energy-efficient computing and aerodynamic sensor stacks.
Submitted by Tim Holme
One theory of how battery solid state electrolytes fail
From Paper: Dendrite nucleation in lithium-conductive ceramics
Solid-state lithium batteries cannot achieve reasonable power densities because of dendrites, whose formation mechanisms remain uncertain. This paper applies principles of chemomechanics to investigate the critical current above which dendrites form in lithium-conductive ceramics. Applied voltage induces stress in solid electrolytes; dendrites appear to nucleate in the exemplary garnet-oxide material Li7La3Zr2O12 (LLZO) when the interfacial pressure exceeds a particular value. The critical pressure of polycrystalline LLZO correlates well with the surface-energy changes incurred by lithium plating in its grain boundaries. A derived formula, validated by experiments, predicts quantitatively how critical current varies with properties including interfacial impedance, bulk permittivity, and grain size. As well as suggesting novel strategies to create more resilient ion-conductive ceramics, the proposed mechanism rationalizes experimental observations of bulk lithium plating and explains how LLZO exhibits an electrically activated transition from stable low-current cyclability to high-current dendrite nucleation.
Submitted by Tim Holme
High-energy long-cycling all-solid-state lithium metal batteries (ASSBs) enabled by silver–carbon composite anodes
From Paper: High-energy long-cycling all-solid-state lithium metal batteries enabled by silver–carbon composite anodes
Published: Mar 2020
  • A series of heating and cutting tests were conducted which confirmed the high safety of the ASSBs based on the SSE.
  • The stacking process during the construction of ASSBs is known to be vital for their performance. With the current prototype cell structure, it is possible to design an energy density of > 1,000/l by increasing the number of cell stacks and cell area.
Submitted by Cullyn Newman
Slide 1 of 1
Lithium Battery Reusing and Recycling: A Circular Economy Insight
Driven by the rapid uptake of battery electric vehicles, Li-ion power batteries are increasingly reused in stationary energy storage systems, and eventually recycled to recover all the valued components. Offering an updated global perspective, this study provides a circular economy insight on lithium-ion battery reuse and recycling.
Submitted by Patrick Joyce
Teardown of Tesla's Lithium-Ion Battery
From Paper: Aging of Tesla’s 18650 Lithium-Ion Cells: Correlating Solid-Electrolyte-Interphase Evolution with Fading in Capacity and Power
The long-term performance of commercial lithium-ion batteries used in today’s electric vehicles is of utmost importance forautomotive requirements. Here, we use Tesla’s 18650 cells manufactured by Panasonic to elucidate the origins of capacity fading andimpedance increase during both calendar and cycle aging. Full cell testing is systematically carried out at three different temperatures(25◦C, 40◦C, 60◦C). The cells are galvanostatically cycled at different C-rates (0.33 C – 1 C) and calendar aging is monitored at 4different state-of-charges (SOC). Operation at high temperatures turns out to have the largest effect on both the capacity and directcurrent (DC) impedance. As an example, after 500 cycles at 25◦C and 40◦C capacity fading is approximately 12%, while at 60◦C thefading reaches 22%. Our DC impedance measurements reveal the same trend. Post mortem analysis indicate that aging is stronglyrelated to changes of the solid electrolyte interphase (SEI). Hence, the changes in performance are correlated with the change incomposition (and thickness) of the SEI formed. In particular, we quantitatively measure the formation of electrically insulating LiFand find a correlation between overall DC impedance of the cells and lithium fluoride of the SEI.
Submitted by Tim Holme
BMW's take on next generation battery materials
From Paper: Future generations of cathode materials: an automotive industry perspective
  • Enabling a lithium metal anode is necessary to make the big improvement in energy density and specific energy that BMW is looking for in EVs
Submitted by Tim Holme
Aerosolized hydrogen peroxide can be used to decontaminate N95 masks exposed to SARS-CoV-2
From Paper: Technical Report for H2O2-Based N95 Reuse Risk Management
  • Using this technique, a 12ft x 12ft room could decontaminate 700 N95 masks every 6-8 hours
  • N95 masks can be decontaminated up to 20 times with hydrogen peroxide vapor without any damage
Submitted by Patrick Joyce
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Nature of the Dirac gap modulation and surface magnetic interaction in axion antiferromagnetic topological insulator MnBi$_2$Te$_4$
M. Shikin, A., et al
Published: Apr 2020
Modification of the gap at the Dirac point (DP) in antiferromagnetic (AFM)axion topological insulator MnBi$_2$Te$_4$ and its electronic and spinstructure has been studied by angle- and spin-resolved photoemissionspectroscopy (ARPES) under laser excitation with variation of temperature(9-35~K), light polarization and photon energy. We have distinguished both alarge (62-67~meV) and a reduced (15-18~meV) gap at the DP in the ARPESdispersions, which remains open above the N\'eel temperature($T_\mathrm{N}=24.5$~K). We propose that the gap above $T_\mathrm{N}$ remainsopen due to short-range magnetic field generated by chiral spin fluctuations.Spin-resolved ARPES, XMCD and circular dichroism ARPES measurements show asurface ferromagnetic ordering for large-gap sample and significantly reducedeffective magnetic moment for the reduced-gap sample. These effects can beassociated with a shift of the topological DC state towards the second Mn layerdue to structural defects and mechanical disturbance, where it is influenced bya compensated effect of opposite magnetic moments.
Retrieved from arxiv
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