<i>In Situ</i> Transmission Electron Microscopy Study of Electrochemical Lithiation and Delithiation Cycling of the Conversion Anode RuO₂

Conversion-type electrodes represent a broad class of materials with a new Li⁺ reactivity concept. Of these materials, RuO₂ can be considered a model material due to its metallic-like conductivity and its high theoretical capacity of 806 mAh/g. In this paper, we use <i>in situ</i> transmission electron microscopy to study the reaction between single-crystal RuO₂ nanowires and Li⁺. We show that a large volume expansion of 95% occurs after lithiation, 26% of which is irreversible after delithiation. Significant surface roughening and lithium embrittlement are also present. Furthermore, we show that the initial reaction from crystalline RuO₂ to the fully lithiated mixed phase of Ru/Li₂O is not fully reversible, passing through an intermediate phase of Li_<i>x</i>RuO₂. In subsequent cycles, the phase transitions are between amorphous RuO₂ in the delithiated state and a nanostructured network of Ru/Li₂O in the fully lithiated phase

<i>In Situ</i> Transmission Electron Microscopy Study of Electrochemical Lithiation and Delithiation Cycling of the Conversion Anode RuO₂

Conversion-type electrodes represent a broad class of materials with a new Li⁺ reactivity concept. Of these materials, RuO₂ can be considered a model material due to its metallic-like conductivity and its high theoretical capacity of 806 mAh/g. In this paper, we use <i>in situ</i> transmission electron microscopy to study the reaction between single-crystal RuO₂ nanowires and Li⁺. We show that a large volume expansion of 95% occurs after lithiation, 26% of which is irreversible after delithiation. Significant surface roughening and lithium embrittlement are also present. Furthermore, we show that the initial reaction from crystalline RuO₂ to the fully lithiated mixed phase of Ru/Li₂O is not fully reversible, passing through an intermediate phase of Li_<i>x</i>RuO₂. In subsequent cycles, the phase transitions are between amorphous RuO₂ in the delithiated state and a nanostructured network of Ru/Li₂O in the fully lithiated phase

<i>In Situ</i> Transmission Electron Microscopy Study of Electrochemical Lithiation and Delithiation Cycling of the Conversion Anode RuO₂

Conversion-type electrodes represent a broad class of materials with a new Li⁺ reactivity concept. Of these materials, RuO₂ can be considered a model material due to its metallic-like conductivity and its high theoretical capacity of 806 mAh/g. In this paper, we use <i>in situ</i> transmission electron microscopy to study the reaction between single-crystal RuO₂ nanowires and Li⁺. We show that a large volume expansion of 95% occurs after lithiation, 26% of which is irreversible after delithiation. Significant surface roughening and lithium embrittlement are also present. Furthermore, we show that the initial reaction from crystalline RuO₂ to the fully lithiated mixed phase of Ru/Li₂O is not fully reversible, passing through an intermediate phase of Li_<i>x</i>RuO₂. In subsequent cycles, the phase transitions are between amorphous RuO₂ in the delithiated state and a nanostructured network of Ru/Li₂O in the fully lithiated phase

Lithium Electrodeposition Dynamics in Aprotic Electrolyte Observed <i>in Situ</i> <i>via</i> Transmission Electron Microscopy

Electrodeposited metallic lithium is an ideal negative battery electrode, but nonuniform microstructure evolution during cycling leads to degradation and safety issues. A better understanding of the Li plating and stripping processes is needed to enable practical Li-metal batteries. Here we use a custom microfabricated, sealed liquid cell for <i>in situ</i> scanning transmission electron microscopy (STEM) to image the first few cycles of lithium electrodeposition/dissolution in liquid aprotic electrolyte at submicron resolution. Cycling at current densities from 1 to 25 mA/cm² leads to variations in grain structure, with higher current densities giving a more needle-like, higher surface area deposit. The effect of the electron beam was explored, and it was found that, even with minimal beam exposure, beam-induced surface film formation could alter the Li microstructure. The electrochemical dissolution was seen to initiate from isolated points on grains rather than uniformly across the Li surface, due to the stabilizing solid electrolyte interphase surface film. We discuss the implications for <i>operando</i> STEM liquid-cell imaging and Li-battery applications

Best maximum likelihood tree of the Teleostei from analysis of the <i>mt-seq</i> data subset “12RT,” using the software RAxML.

<p>Branch lengths are proportional to the number of substitutions per nucleotide position (scale bar  = 0.05 substitutions). Numbers at nodes give node support in terms of bootstrap proportions. The tree is rooted with <i>Amia calva</i>. Light grey gradient boxes highlight the Mormyroidea (African weakly electric fishes) and the Gymnotiformes (South American weakly electric fishes). Arrowheads indicate nodes for which topological differences were found compared to trees reconstructed using the two other data subsets (“123ryRT” and “123RT,” shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287.s001" target="_blank">Fig. S1</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287.s002" target="_blank">S2</a>, respectively).</p

Phylogenetic distribution of electroreception within the Craniata and its evolution according to the criterion of parsimony.

<p>The phylogenetic backbone shown here follows Nelson <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-Nelson1" target="_blank">[140]</a>, with modifications according to Gardiner et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-Gardiner1" target="_blank">[141]</a>, Lavoué et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-Lavou6" target="_blank">[119]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-Lavou7" target="_blank">[142]</a>, Heimberg et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-Heimberg1" target="_blank">[143]</a>, Kikugawa et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-Kikugawa1" target="_blank">[144]</a>, Li et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-Li3" target="_blank">[120]</a>, and Takezaki et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-Takezaki1" target="_blank">[145]</a>. Approximate timeline adapted from the fossil record; data on electroreception and electroreceptors taken from Bullock et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-Bullock1" target="_blank">[1]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-Bullock2" target="_blank">[26]</a> and Albert and Crampton <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-Albert1" target="_blank">[25]</a>. Colored branches indicate electroreceptive lineages possessing electroreceptors: as modified mucous glands (orange); of the ampullary sense organ type (deep blue); of both the tuberous sense organ type and the ampullary sense organ type found in teleosts (yellow). White branches signify non-electroreceptive lineages following secondary loss of electroreceptive capability; four (possibly five) such losses are indicated by white hash marks. The origins of different forms of electroreception are indicated by black hash marks. The electroreceptive conditions of the ancestors of the Craniata and of the clade (hagfishes, lampreys) are unresolved (indicated with grey and question marks) because there are several equi-parsimonious hypotheses concerning them. The end bud electroreceptor of the lampreys and the ampullary electroreceptor of the basal gnathostomes are anatomically very different, suggesting independent origins. The tree does not map atypical reports of electroreceptive gains in single species, which are in need of further study, such as tuberous electroreceptors in a blind catfish <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-Andres1" target="_blank">[146]</a>. Recently, Czech-Damal et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-CzechDamal1" target="_blank">[147]</a> discovered a novel sensory organ and possible electroreceptors associated with the hairless vibrissal crypts on the snout of the Guiana Dolphin (<i>Sotalia guianensis</i>), which appear to be sensitive to weak D.C. electric fields on the order of 4.6 microvolts per cm. Although their studies so far involve only one captive specimen trained to respond to the presence or absence of weak electric fields, it indeed suggests that additional research is needed on the sensory capabilities of aquatic mammals that might have independently evolved electroreception. Piranha (<i>Catoprion mento</i>) and platypus illustrations modified from images downloaded from Wikimedia Commons; paddlefish (<i>Polyodon spathula</i>) illustration modified from NOAA’s Historic Fisheries Collection Catalog of Images; other fish illustrations modified from Nelson <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-Nelson1" target="_blank">[140]</a>; other tetrapod illustrations taken from Léo Lavoué’s coloring book.</p

Phylogenetic chronogram of the Teleostei based on a Bayesian relaxed clock approach using the <i>mt-seq</i> data subset “12RT” under the second fossil calibration strategy.

<p>In this approach, we used 17 fossil-derived calibration constraints following uniform distributions (i.e., reconstruction #2). 95% age credibility intervals are shown as black horizontal bars (calibration constraints on corresponding nodes), yellow horizontal bars (focal nodes of interest), and white horizontal bars (all other nodes). Daggers indicate that minimum ages were used to calibrate the nodes, and adjacent numbers in brackets refer to source fossils listed in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#s4" target="_blank">Materials and Methods</a>. Dashed lines between daggers and lower age limits of corresponding nodes (within the 95% age credibility intervals) depict putative ghost lineages in the fossil record. All other details as in Fig. 4.</p

Previously estimated ages of the Mormyroidea and the Gymnotiformes.

1<p>Identified as <i>Marcusenius</i> sp. in Kumazawa and Nishida <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-Kumazawa1" target="_blank">[83]</a>; ²the order Characiformes was found not to be monophyletic by Peng et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-Peng1" target="_blank">[84]</a>.</p><p>Ages were inferred from direct evidence (based on the fossil record, with strict minimum ages <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-Gayet1" target="_blank">[70]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-Murray1" target="_blank">[72]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-Patterson2" target="_blank">[94]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-Forey1" target="_blank">[148]</a>) or via indirect evidence (molecular-based estimates <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-AlvesGomes3" target="_blank">[82]</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-Lavou4" target="_blank">[87]</a>). Ages are given as millions of years ago (Mya). Following convention, daggers (†) indicate extinct taxa.</p

Distributions of estimated ages for focal nodes of interest under each fossil calibration scheme.

<p>For each plot, estimated ages were sampled every 5,000 generations from two independent BEAST runs of 1×10⁸ generations each. Resulting age histograms are shown for the estimated times of the most recent common ancestors (tMRCAs) of the Mormyroidea and the Gymnotiformes (<b>A</b>) under reconstruction #1 (also see Fig. 4) and (<b>C</b>) under reconstruction #2 (also see Fig. 5); histograms are similarly shown for tMRCAs of the Notopteroidei and the Characiphysae under (<b>B</b>) reconstruction #1 and (<b>D</b>) reconstruction #2. The span of blue bars along the vertical axis of each plot gives the 95% credibility interval for that particular age estimate. Tails of each distribution are shown in red. All time scales in millions of years ago (Mya).</p

Phylogenetic chronogram of the Teleostei based on a Bayesian relaxed clock approach using the <i>mt-seq</i> data subset “12RT” under the first fossil calibration strategy.

<p>In this approach, we used seven fossil-derived calibration constraints following lognormal distributions and ten others following uniform distributions (i.e., reconstruction #1). <i>Amia calva</i> is used to root the tree. Light grey gradient boxes highlight the Mormyroidea and Gymnotiformes. Horizontal timescale is in millions of years ago (Mya). Only selected epoch names are given. Abbreviations: E, early; Paleo, Paleocene; Eo, Eocene; and Oligo, Oligocene. Standardized timescale colors taken from the Commission for the Geological Map of the World. 95% age credibility intervals are shown as black and grey horizontal bars (calibration constraints on corresponding nodes), yellow horizontal bars (focal nodes of interest), and white horizontal bars (all other nodes). Daggers indicate that minimum ages were used to calibrate the nodes, and adjacent numbers in brackets refer to source fossils listed in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#s4" target="_blank">Materials and Methods</a>. Numbers at nodes are the posterior probability support values (shown only when <1). Timing of the separation of Africa and South America is depicted by the three insets at the top, modified from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036287#pone.0036287-Lawver1" target="_blank">[81]</a>. Here, “origin of electroreception” refers to the initial origin of any kind of electroreceptive system in the broadest sense (see text for elaboration).</p