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"Knapp, Michael"
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Data-driven capacity estimation of commercial lithium-ion batteries from voltage relaxation
Accurate capacity estimation is crucial for the reliable and safe operation of lithium-ion batteries. In particular, exploiting the relaxation voltage curve features could enable battery capacity estimation without additional cycling information. Here, we report the study of three datasets comprising 130 commercial lithium-ion cells cycled under various conditions to evaluate the capacity estimation approach. One dataset is collected for model building from batteries with LiNi
0.86
Co
0.11
Al
0.03
O
2
-based positive electrodes. The other two datasets, used for validation, are obtained from batteries with LiNi
0.83
Co
0.11
Mn
0.07
O
2
-based positive electrodes and batteries with the blend of Li(NiCoMn)O
2
- Li(NiCoAl)O
2
positive electrodes. Base models that use machine learning methods are employed to estimate the battery capacity using features derived from the relaxation voltage profiles. The best model achieves a root-mean-square error of 1.1% for the dataset used for the model building. A transfer learning model is then developed by adding a featured linear transformation to the base model. This extended model achieves a root-mean-square error of less than 1.7% on the datasets used for the model validation, indicating the successful applicability of the capacity estimation approach utilizing cell voltage relaxation.
Accurate capacity estimation is crucial for lithium-ion batteries' reliable and safe operation. Here, the authors propose an approach exploiting features from the relaxation voltage curve for battery capacity estimation without requiring other previous cycling information.
Journal Article
Lithium lanthanum titanate perovskite as an anode for lithium ion batteries
Conventional lithium-ion batteries embrace graphite anodes which operate at potential as low as metallic lithium, subjected to poor rate capability and safety issues. Among possible alternatives, oxides based on titanium redox couple, such as spinel Li
4
Ti
5
O
12
, have received renewed attention. Here we further expand the horizon to include a perovskite structured titanate La
0.5
Li
0.5
TiO
3
into this promising family of anode materials. With average potential of around 1.0 V vs. Li
+
/Li, this anode exhibits high specific capacity of 225 mA h g
−1
and sustains 3000 cycles involving a reversible phase transition. Without decrease the particle size from micro to nano scale, its rate performance has exceeded the nanostructured Li
4
Ti
5
O
12
. Further characterizations and calculations reveal that pseudocapacitance dictates the lithium storage process and the favorable ion and electronic transport is responsible for the rate enhancement. Our findings provide fresh impetus to the identification and development of titanium-based anode materials with desired electrochemical properties.
Exploration of high performance materials for lithium storage presents as a critical challenge. Here authors report micron-sized La
0.5
Li
0.5
TiO
3
as a promising anode material, which demonstrates improved capacity, rate capability and suitable voltage as anode for lithium ion batteries.
Journal Article
Structural insights into the formation and voltage degradation of lithium- and manganese-rich layered oxides
One major challenge in the field of lithium-ion batteries is to understand the degradation mechanism of high-energy lithium- and manganese-rich layered cathode materials. Although they can deliver 30 % excess capacity compared with today’s commercially- used cathodes, the so-called voltage decay has been restricting their practical application. In order to unravel the nature of this phenomenon, we have investigated systematically the structural and compositional dependence of manganese-rich lithium insertion compounds on the lithium content provided during synthesis. Structural, electronic and electrochemical characterizations of Li
x
Ni
0.2
Mn
0.6
O
y
with a wide range of lithium contents (0.00 ≤
x
≤ 1.52, 1.07 ≤
y
< 2.4) and an analysis of the complexity in the synthesis pathways of monoclinic-layered Li[Li
0.2
Ni
0.2
Mn
0.6
]O
2
oxide provide insight into the underlying processes that cause voltage fading in these cathode materials, i.e. transformation of the lithium-rich layered phase to a lithium-poor spinel phase via an intermediate lithium-containing rock-salt phase with release of lithium/oxygen.
The authors here look into the phase transitions in Li-/Mn-rich layered cathode materials during synthesis and cycling. It is revealed that the Li-rich layered structure tends to transform to a Li-poor spinel phase via an intermediate Li-containing rock salt phase, with release of lithium/oxygen.
Journal Article
Complete mitochondrial genome sequence of a Middle Pleistocene cave bear reconstructed from ultrashort DNA fragments
Although an inverse relationship is expected in ancient DNA samples between the number of surviving DNA fragments and their length, ancient DNA sequencing libraries are strikingly deficient in molecules shorter than 40 bp. We find that a loss of short molecules can occur during DNA extraction and present an improved silica-based extraction protocol that enables their efficient retrieval. In combination with single-stranded DNA library preparation, this method enabled us to reconstruct the mitochondrial genome sequence from a Middle Pleistocene cave bear (Ursus deningeri) bone excavated at Sima de los Huesos in the Sierra de Atapuerca, Spain. Phylogenetic reconstructions indicate that the U. deningeri sequence forms an early diverging sister lineage to all Western European Late Pleistocene cave bears. Our results prove that authentic ancient DNA can be preserved for hundreds of thousand years outside of permafrost. Moreover, the techniques presented enable the retrieval of phylogenetically informative sequences from samples in which virtually all DNA is diminished to fragments shorter than 50 bp.
Journal Article
We’re all in this together: Focus on community attenuates effects of pandemic-related financial hardship on reactance to COVID-19 public health regulations
There has been resistance to COVID-19 public health restrictions partly due to changes and reductions in work, resulting in financial stress. Psychological reactance theory posits that such restrictions to personal freedoms result in anger, defiance, and motivation to restore freedom. In an online study (N = 301), we manipulated the target of COVID-19 restrictions as impacting self or community. We hypothesized that (a) greater pandemic-related financial stress would predict greater reactance, (b) the self-focused restriction condition would elicit greater reactance than the community-focused restriction condition, (c) reactance would be greatest for financially-stressed individuals in the self-focused condition, and (d) greater reactance would predict lower adherence to social distancing guidelines. Independent of political orientation and sense of community, greater financial stress predicted greater reactance only in the self-focused condition; the community-focused condition attenuated this association. Additionally, greater reactance was associated with lower social distancing behavior. These findings suggest that economic hardship exacerbates negative responses to continued personal freedom loss. Community-focused COVID-19 health messaging may be better received during continued pandemic conditions.
Journal Article
Tailoring superstructure units for improved oxygen redox activity in Li-rich layered oxide battery’s positive electrodes
The high-voltage oxygen redox activity of Li-rich layered oxides enables additional capacity beyond conventional transition metal (TM) redox contributions and drives the development of positive electrode active materials in secondary Li-based batteries. However, Li-rich layered oxides often face voltage decay during battery operation. In particular, although Li-rich positive electrode active materials with a high nickel content demonstrate improved voltage stability, they suffer from poor discharge capacity. Here, via physicochemical and electrochemical measurements, we investigate the correlation between oxygen redox activity and superstructure units in Li-rich layered oxides, specifically the fractions of LiMn
6
and Ni
4+
-stabilized LiNiMn
5
within the TM layer. We prove that an excess of LiNiMn
5
hinders the extraction/insertion of lithium ions during Li metal coin cell charging/discharging, resulting in incomplete oxygen redox activity at a cell potential of about 3.3 V. We also demonstrate that lithium content adjustment could be a beneficial approach to tailor the superstructure units. Indeed, we report an improved oxygen redox reversibility for an optimized Li-rich layered oxide with fewer LiNiMn
5
units.
The high-voltage oxygen redox activity of Li-rich layered oxides enables additional capacity beyond conventional transition metal redox contributions. Here, authors investigate the correlation between oxygen redox activity and superstructure units. They prove that an excess of LiNiMn5 hinders the extraction/insertion of lithium ions.
Journal Article
Tuning Li occupancy and local structures for advanced Co-free Ni-rich positive electrodes
Structure evolution and surface reactivity have long been regarded as the most crucial points for studying Ni-rich positive electrodes for Li-ion batteries. Unfortunately, the influence of Li occupancy as a single factor on electro-chemomechanical stability has been overlooked and is missing, owing to the challenge of Li determination in the lattice. Here, a comprehensive analysis reveals different Li occupancies and related structural domains (Ni/Li exchange, Li
a
XO
b
, Li/Mn/X(Ni) ordering domains, X = Nb
5+
, W
6+
, and Mo
6+
) by using a combination of Li-sensitive characterization techniques. By introducing a Li-regulation strategy, the relative ratio of each domain is effectively tuned in the Ni-rich positive electrodes. Through tuning, two specific positive electrodes are designed, exhibiting notable improvement in battery cyclability. The specific Li structural units induce significant changes in redox mechanisms. This Li-occupancy-tuning approach highlights the necessity of focusing on Li distribution and opens up ideas for designing advanced Ni-rich positive electrodes with high durability.
The influence of Li occupancy on electro-chemomechanical stability in Co-free Ni-rich layered oxides for Li-ion batteries has been overlooked. Here, authors investigate different Li structural units in the oxide lattice and show that tuning the Li occupancy improves battery cycling stability.
Journal Article
Identification of the remains of King Richard III
In 2012, a skeleton was excavated at the presumed site of the Grey Friars friary in Leicester, the last-known resting place of King Richard III. Archaeological, osteological and radiocarbon dating data were consistent with these being his remains. Here we report DNA analyses of both the skeletal remains and living relatives of Richard III. We find a perfect mitochondrial DNA match between the sequence obtained from the remains and one living relative, and a single-base substitution when compared with a second relative. Y-chromosome haplotypes from male-line relatives and the remains do not match, which could be attributed to a false-paternity event occurring in any of the intervening generations. DNA-predicted hair and eye colour are consistent with Richard’s appearance in an early portrait. We calculate likelihood ratios for the non-genetic and genetic data separately, and combined, and conclude that the evidence for the remains being those of Richard III is overwhelming.
King Richard III was a controversial English King whose remains are presumably deposited in Grey Friars in Leicester. Here the authors sequence the mitochondrial genome and Y-chromosome DNA of the skeletal remains and living relatives of Richard III and confirm that the remains belong to King Richard III.
Journal Article
Odorant binding protein 69a connects social interaction to modulation of social responsiveness in Drosophila
Living in a social environment requires the ability to respond to specific social stimuli and to incorporate information obtained from prior interactions into future ones. One of the mechanisms that facilitates social interaction is pheromone-based communication. In Drosophila melanogaster, the male-specific pheromone cis-vaccenyl acetate (cVA) elicits different responses in male and female flies, and functions to modulate behavior in a context and experience-dependent manner. Although it is the most studied pheromone in flies, the mechanisms that determine the complexity of the response, its intensity and final output with respect to social context, sex and prior interaction, are still not well understood. Here we explored the functional link between social interaction and pheromone-based communication and discovered an odorant binding protein that links social interaction to sex specific changes in cVA related responses. Odorant binding protein 69a (Obp69a) is expressed in auxiliary cells and secreted into the olfactory sensilla. Its expression is inversely regulated in male and female flies by social interactions: cVA exposure reduces its levels in male flies and increases its levels in female flies. Increasing or decreasing Obp69a levels by genetic means establishes a functional link between Obp69a levels and the extent of male aggression and female receptivity. We show that activation of cVA-sensing neurons is sufficeint to regulate Obp69a levels in the absence of cVA, and requires active neurotransmission between the sensory neuron to the second order olfactory neuron. The cross-talk between sensory neurons and non-neuronal auxiliary cells at the olfactory sensilla, represents an additional component in the machinery that promotes behavioral plasticity to the same sensory stimuli in male and female flies.
Journal Article