Sulfur Nanodots Electrodeposited on Ni Foam as High-Performance Cathode for Li–S Batteries

In this Letter, we report the preparation of sulfur nanodots (2 nm average) electrodeposited on flexible nickel foam and their application as high-performance cathode of Li–S batteries. An electrodepostion method was applied to prepare the cathode at room temperature and the sulfur mass was controllable from 0.21 to 4.79 mg/cm² in a large area of over 100 cm². The optimized cathode with 0.45 mg/cm² S on Ni foam displayed high initial discharge capacity (1458 mAh/g at 0.1 C), high rate capability (521 mAh/g at 10 C), and long cycling stability (895 mAh/g after 300 cycles at 0.5 C and 528 mAh/g after 1400 cycles at 5 C). Moreover, in situ Raman and transmission electron microscopy analysis demonstrated the fundamentals of reversible electrochemical reaction between S and Li₂S nanodots. This fast, facile, and one-step cathode preparation method with excellent electrochemical performance will lead to technological advances of S cathode in Li–S batteries

MCNTs@MnO₂ Nanocomposite Cathode Integrated with Soluble O₂‑Carrier Co-salen in Electrolyte for High-Performance Li–Air Batteries

Li–air batteries (LABs) are promising because of their high energy density. However, LABs are troubled by large electrochemical polarization during discharge and charge, side reactions from both carbon cathode surface/peroxide product and electrolyte/superoxide intermediate, as well as the requirement for pure O₂. Here we report the solution using multiwall carbon nanotubes (MCNTs)@MnO₂ nanocomposite cathode integrated with <i>N</i>,<i>N</i>′-bis­(salicylidene)­ethylenediaminocobalt­(II) (Co^II-salen) in electrolyte for LABs. The advantage of such a combination is that on one hand, the coating layer of δ-MnO₂ with about 2–3 nm on MCNTs@MnO₂ nanocomposite catalyzes Li₂O₂ decomposition during charge and suppresses side reactions between product Li₂O₂ and MCNT surface. On the other hand, Co^II-salen works as a mobile O₂-carrier and accelerates Li₂O₂ formation through the reaciton of (Co^III-salen)₂-O₂^2– + 2Li⁺ + 2e^– → 2Co^II-salen + Li₂O₂. This reaction route overcomes the pure O₂ limitation and avoids the formation of aggressive superoxide intermediate (O₂^– or LiO₂), which easily attacks organic electrolyte. By using this double-catalyst system of Co-salen/MCNTs@MnO₂, the lifetime of LABs is prolonged to 300 cycles at 500 mA g^–1 (0.15 mA cm^–2) with fixed capacity of 1000 mAh g^–1 (0.30 mAh cm^–2) in dry air (21% O₂). Furthermore, we up-scale the capacity to 500 mAh (5.2 mAh cm^–2) in pouch-type batteries (∼4 g, 325 Wh kg^–1). This study should pave a new way for the design and construction of practical LABs

Enabling All-Solid-State Lithium–Carbon Dioxide Battery Operation in a Wide Temperature Range

Flexible all-solid-state lithium–carbon dioxide batteries (FASSLCBs) are recognized as a next-generation energy storage technology by solving safety and shuttle effect problems. However, the present FASSLCBs rely heavily on high-temperature operation due to sluggish solid–solid–gas multiphase mass transfer and unclear capacity degradation mechanism. Herein, we designed bicontinuous hierarchical porous structures (BCHPSs) for both solid polymer electrolyte and cathode for FASSLCBs to facilitate the mass transfer in all connected directions. The formed large Lewis acidic surface effectively promotes the lithium salt dissociation and the CO2 conversion. Furthermore, it is unraveled that the battery capacity degradation originates from the “dead Li2CO3” formation, which is inhibited by the fast decomposition of Li2CO3. Accordingly, the assembled FASSLCBs exhibit an excellent cycling stability of 133 cycles at 60 °C, which is 2.7 times longer than that without BCHPSs, and the FASSLCBs can be operated repeatedly even at room temperature. This BCHPS method and fundamental deactivation mechanism provide a perspective for designing FASSLCBs with long cycling life

Experimental data of HES

Original experimental data of HE

Brain regions showing marked difference of efficiency between PD and HC.

†<p>FDR multiple comparison correction (p<0.05, cluster size>50).</p><p>PD, Parkinson's disease; HC, healthy control; L, left; R, right; PoCG, postcentral gyrus; M1, primary motor cortex; SMA-proper, supplementary motor area-proper; pre-SMA, pre-supplementary motor area; PUT, putamen; THA, thalamus; GP, globus pallidus.</p><p>Brain regions showing marked difference of efficiency between PD and HC.</p

Demographic and clinical characteristics of the PD and HC groups.

a<p>The p value was calculated using two-tail two-sample t test.</p>b<p>The p value was calculated using chi-squared test.</p><p>PD, Parkinson's disease; HC, healthy control; R, right.</p><p>Demographic and clinical characteristics of the PD and HC groups.</p

Brain regions with blue color indicated significant (FDR multiple comparison correction, p<0.05) decreases of efficiency map in PD relative to healthy control using two-tailed two sample t test with age, gender and frame-wise displacement as covariance.

<p>Those regions were presented in axial view. HC, healthy control; PD, Parkinson's disease.</p

Association of UPDRS motor score with nodal efficiency value in brain areas obtained from comparison of efficiency map between the two groups.

<p>UPDRS motor score was significantly correlated with efficiency value in the left M1, right pre-SMA, bilateral GP and THA (p<0.05). The r_s donates the spearman correlation coefficient. M1, primary motor cortex; pre-SMA, pre-supplementary motor area; GP, globus pallidus; THA, thalamus.</p

Schematic illustration of analysis.

<p>We first constructed functional connectivity network (step A–D) within the CBG motor network (A) at voxel-wise scale (B), and optimal sparsity threshold was estimated and applied (D). Once network was constructed, efficiency for each node was computed and efficiency map for each subject was generated (E).</p

High-Performance Lithium–Sulfur Batteries via Molecular Complexation

Beyond lithium-ion technologies, lithium–sulfur batteries stand out because of their multielectron redox reactions and high theoretical specific energy (2500 Wh kg–1). However, the intrinsic irreversible transformation of soluble lithium polysulfides to solid short-chain sulfur species (Li2S2 and Li2S) and the associated large volume change of electrode materials significantly impair the long-term stability of the battery. Here we present a liquid sulfur electrode consisting of lithium thiophosphate complexes dissolved in organic solvents that enable the bonding and storage of discharge reaction products without precipitation. Insights garnered from coupled spectroscopic and density functional theory studies guide the complex molecular design, complexation mechanism, and associated electrochemical reaction mechanism. With the novel complexes as cathode materials, high specific capacity (1425 mAh g–1 at 0.2 C) and excellent cycling stability (80% retention after 400 cycles at 0.5 C) are achieved at room temperature. Moreover, the highly reversible all-liquid electrochemical conversion enables excellent low-temperature battery operability (>400 mAh g–1 at −40 °C and >200 mAh g–1 at −60 °C). This work opens new avenues to design and tailor the sulfur electrode for enhanced electrochemical performance across a wide operating temperature range