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Na Superionic Conductor (NASICON) materials stand out as an important class of ionic conductors, offering high ionic conductivity and notable electrochemical stability for applications such as solid electrolytes. While advances through compositional engineering have been made to enhance the ionic conductivity of NASICONs, the fundamental mechanisms underlying their superionic conducting behavior remain unresolved. In this study, the interplay between local and global factors—specifically, bottleneck volume and Na site ordering— that influence ionic conduction within the NASICON framework is elucidated. Analysis of reported ionic conductivity data indicates that optimal bottleneck volumes exceed 3.7 Å3, adjustable through the choice of metal cations and polyanions. Additionally, the findings imply that weaker Na site ordering, which enhances ionic conduction, can be induced by increasing the Na content, selecting metal cations with a d0 electron configuration, or mixing elements at the cation or polyanion sites. Moreover, it is proposed that the predominant diffusion mechanism can shift between occupancy‐conserved hopping (OCH), occurring under conditions of strong Na site ordering, and single‐ion hopping (SIH), which becomes possible when site ordering is minimal. These insights offer strategic guidelines for designing NASICONs with superionic conductivity, promoting the development of solid electrolytes for safer and more energy‐dense all‐solid‐state batteries. [ABSTRACT FROM AUTHOR]

Garnet-type Li7La3Zr2O12 (LLZO) is one of the most promising solid-state electrolytes (SSEs). However, the application of LLZO is limited by structural instability, low ionic conductivity, and poor lithium stability. To obtain a garnet-type solid electrolyte with a stable structure and high ionic conductivity, a series of TaCe co-doping cubic Li6·4La3Zr1.4-xTa0.6CexO12 (LLZTCO, x = 0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, 0.30) electrolytes were successfully synthesized through conventional solid-phase method. The Ta5+ doping can introduce more lithium vacancies and effectively maintain the stability of the cubic phase. The Ce4+ with a larger ionic radius is introduced into the lattice to widen the Li+ migration bottleneck size, which significantly increased the ionic conductivity to 1.05 × 10−3 S/cm. It also shows excellent stability to lithium metal by the optimization of Li+ transport channel. Li||LLZTCO||Li symmetric cells can cycle stably for more than 6 000 h at a current density of 0.1 mA/cm2 without any surface modifications. The commercialization potential of LLZTCO samples in all solid-state lithium batteries (ASSLBs) is confirmed by the prepared LiFePO4||LLZTCO||Li cells with a capacity retention rate of 98% after 100 cycles at 0.5C. This new co-doping method presents a practical solution for the realization of high-performance ASSLBs.

With increasing resolution of microbial diversity at the genomic level, experimental and modeling frameworks that translate such diversity into phenotypes are highly needed. This is particularly important when comparing drug-resistant with drug-sensitive pathogen strains, when anticipating epidemiological implications of microbial diversity, and when designing control measures. Classical approaches quantify differences between microbial strains using the exponential growth model, and typically report a selection coefficient for the relative fitness differential between two strains. The apparent simplicity of such approaches comes with the costs of limiting the range of biological scenarios that can be captured, and biases strain fitness estimates to polarized extremes of competitive exclusion. Here, we propose a mathematical and statistical framework based on the Lotka-Volterra model, that can capture frequency-dependent competition between microbial strains within-host and upon transmission. As a proof-of-concept, the model is applied to a previously-published dataset from in-vivo competitive mixture experiments with influenza strains in ferrets (McCaw et al., 2011). We show that for the same data, our model predicts a scenario of coexistence between strains, and supports a higher bottleneck size in the range of 35–145 virions transmitted from donor to recipient host. Thanks to its simplicity and generality, such framework could be applied to other ecological scenarios of microbial competition, enabling a more complex and nuanced view of possible outcomes between two strains, beyond competitive exclusion.

With increasing resolution of microbial diversity at the genomic level, experimental and modeling frameworks that translate such diversity into phenotypes are highly needed. This is particularly important when comparing drug-resistant with drug-sensitive pathogen strains, when anticipating epidemiological implications of microbial diversity, and when designing control measures. Classical approaches quantify differences between microbial strains using the exponential growth model, and typically report a selection coefficient for the relative fitness differential between two strains. The apparent simplicity of such approaches comes with the costs of limiting the range of biological scenarios that can be captured, and biases strain fitness estimates to polarized extremes of competitive exclusion. Here, we propose a mathematical and statistical framework based on the Lotka-Volterra model, that can capture frequency-dependent competition between microbial strains within-host and upon transmission. As a proof-of-concept , the model is applied to a previously-published dataset from in-vivo competitive mixture experiments with influenza strains in ferrets (McCaw et al., 2011). We show that for the same data, our model predicts a scenario of coexistence between strains, and supports a higher bottleneck size in the range of 35–145 virions transmitted from donor to recipient host. Thanks to its simplicity and generality, such framework could be applied to other ecological scenarios of microbial competition, enabling a more complex and nuanced view of possible outcomes between two strains, beyond competitive exclusion. [ABSTRACT FROM AUTHOR]

Experimental evolution is a powerful tool to study genetic trajectories to antibiotic resistance under selection. A confounding factor is that outcomes may be heavily influenced by the choice of experimental parameters. For practical purposes (minimizing culture volumes), most experimental evolution studies with bacteria use transmission bottleneck sizes of 5 × 106 cfu. We currently have a poor understanding of how the choice of transmission bottleneck size affects the accumulation of deleterious versus high-fitness mutations when resistance requires multiple mutations, and how this relates outcome to clinical resistance. We addressed this using experimental evolution of resistance to ciprofloxacin in Escherichia coli. Populations were passaged with three different transmission bottlenecks, including single cell (to maximize genetic drift) and bottlenecks spanning the reciprocal of the frequency of drug target mutations (108 and 1010). The 1010 bottlenecks selected overwhelmingly mutations in drug target genes, and the resulting genotypes corresponded closely to those found in resistant clinical isolates. In contrast, both the 108 and single-cell bottlenecks selected mutations in three different gene classes: 1) drug targets, 2) efflux pump repressors, and 3) transcription-translation genes, including many mutations with low fitness. Accordingly, bottlenecks smaller than the average nucleotide substitution rate significantly altered the experimental outcome away from genotypes observed in resistant clinical isolates. These data could be applied in designing experimental evolution studies to increase their predictive power and to explore the interplay between different environmental conditions, where transmission bottlenecks might vary, and resulting evolutionary trajectories. [ABSTRACT FROM AUTHOR]

Molecular dynamic simulations were performed on element-screened Li7La3Zr2O12 (LLZO)-equivalent doping system to reveal the effect of bottleneck (surface between the polyhedron of 24d and 96h site in cubic LLZO) size on lithium ion diffusion in this garnet-type solid electrolyte. The relationship between lithium ion diffusivity, lattice constant (volume), and bottleneck size were further studied. Herein, we found unneglectable discreteness between lattice constant (volume) and lithium ion diffusivity; beyond that, a quasi-linear relationship between bottleneck size and lithium ion diffusivity under high temperature (1000~1400 K) was unveiled. Our results show that by simply regulating the bottleneck size, the diffusion properties of lithium garnets can be further improved. [ABSTRACT FROM AUTHOR]

Bottleneck size is the minimum Li+ migration channel of Li7La3Zr2O12 (LLZO) and it greatly influences the Li+ conductivity. Doping different elements on the Zr site of LLZO can adjust the bottleneck size and improve the Li+ conductivity. However, the regulation mechanism is not clear. In this work, Li6.4La3Zr1.4M0.6O12 (M = Sb, Ta, Nb) has been prepared and the bottleneck size has been adjusted by doping different pentavalent ions. The results manifest that the cell parameter and bottleneck size decrease with the rise of the radius of doped pentavalent ions. This is because larger pentavalent ion leads to larger bond length of M–O, and weaker covalent component between M5+ and O2‐, corresponding, the formal charge on the M5+ become larger, and the bond length of La–O slightly decreases due to the coulomb repulsion between La3+ and M5+ increase. While, the activation energy drop firstly and then rise with the rise of bottleneck size because of the migration of Li+ not only relate to the size of the migration channel but also to the strength of M–O covalent bonding. The bottleneck size and bond length of M–O synergistically affect the migration of Li+. [ABSTRACT FROM AUTHOR]

The garnet-type lithium ion conductor, nominal Li 7 La 3 Zr 2 O 12 (LLZO) has received a lot of interest as they are considered usable as solid electrolytes in lithium battery. The Li + migration bottleneck size of garnet-type Li 7 La 3 Zr 2 O 12 (LLZO) solid electrolyte are posed significant effect on Li + transportation property. However, the regulation mechanism of the bottleneck size on the Li + migration activation energy is not clear. In the study, equivalent substitution of tetravalent M 4+ (M 4+  = Ge 4+ , Ti 4+ , Sn 4+ , Hf 4+ and Te 4+ ) ions on Zr site of Li 7 La 3 M 0.25 Zr 1.75 O 12 is designed to regulate the bottleneck size. X-ray absorption fine structure (XAFS) is applied to detect the quantitative structural information of M-doped LLZO. Experimental and calculations results show that the M 4+ substitution regulate the Li + migration bottleneck size via changing M–O bond length. The M–O bond length increases with the increase of M 4+ doping ion radius which results in the increase of the bottleneck size. However, larger bottleneck size is not necessarily favorable for Li + migration. Ge 4+ and Ti 4+ doped LLZO have smaller bottleneck size than the un-doped LLZO, which is more suitable for Li + migration (corresponds to lower E a of 0.28 eV, 0.29 eV, respectively). This study is of great significance for obtaining optimum lithium ion migration channel size for LLZO, and the regulation mechanism is universality for crystal ion conductors. [ABSTRACT FROM AUTHOR]