Functional Role of Aramid Coated Separator for Dendrite Suppression in Lithium-Ion Batteries

The separator is an essential important key material in lithium-ion batteries (LIBs) because it is in contact with the positive and negative electrodes and the electrolyte. Aramid coated separators (ACS) are widely used in automotive and consumer batteries as high-performance separators for LIBs with high safety and excellent lifetime characteristics. Although much effort has been made to improve the electrolyte composition, the lithium deposition on the surface of the graphite electrode at low temperature and the high charge rate is still an unsolved problem in LIBs. In this work, lithium metal is used as a counter electrode, and a separator was placed between lithium metal and graphite composite electrode. The lithium was deposited on the surface of the graphite composite electrode through the separator. Then, the functional role of ACS in the initial deposition process was investigated. The dendrite blocking effect of ACS was studied by the observation of dendrite growth and pulse cycle performance.

Preparation of Hollow Core–Shell Fe3O4/Nitrogen-Doped Carbon Nanocomposites for Lithium-Ion Batteries

Iron oxides are potential electrode materials for lithium-ion batteries because of their high theoretical capacities, low cost, rich resources, and their non-polluting properties. However, iron oxides demonstrate large volume expansion during the lithium intercalation process, resulting in the electrode material being crushed, which always results in poor cycle performance. In this paper, to solve the above problem, iron oxide/carbon nanocomposites with a hollow core–shell structure were designed. Firstly, an Fe2O3@polydopamine nanocomposite was prepared using an Fe2O3 nanocube and dopamine hydrochloride as precursors. Secondly, an Fe3O4@N-doped C composite was obtained by means of further carbonization treatment. Finally, Fe3O4@void@N-Doped C-x composites with core–shell structures with different void sizes were obtained by means of Fe3O4 etching. The effect of the etching time on the void size was studied. The electrochemical properties of the composites when used as lithium-ion battery materials were studied in more detail. The results showed that the sample that was obtained via etching for 5 h using 2 mol L−1 HCl solution at 30 °C demonstrated better electrochemical performance. The discharge capacity of the Fe3O4@void@N-Doped C-5 was able to reach up to 1222 mA g h−1 under 200 mA g−1 after 100 cycles.

POM-based Metal Organic Frameworks with Woven Fabric Structure for Lithium Storage

The development of new anode materials for LIBs with high specific energy density and long cycle performance have been became urgent increasing demand for further applications. Polyoxometalates (POMs), as a...

Rational design of nickel-cobalt selenides@selenium nanostructure by adjusting the synthesis environment for high performance sodium-ion batteries

The exploitation of metal selenides in sodium-ion batteries has attracted significant interest. However, an effective balance among their energy density, rate and cycle performance has been beset, as the complexity...

Ultraflexible All-in-one Supercapacitors with High Capacitance and Ultrastable Cycle Performance Enabled by Wood Cellulose Network

Herein, we demonstrate a structure-enabled strategy to construct an ultrastable, high-performance, ultraflexible all-in-one supercapacitor with a one-piece wood cellulose network/polyaniline/multiwalled carbon nanotube composite as both the electrodes and the separator....

Communication—Lithium Titanate as Mg-Ion Insertion Anode for Mg-Ion Sulfur Batteries Based on Sulfurated Poly(acrylonitrile) Composite

Spinel lithium-titanate Li4Ti5O12 (LTO) is a promising anode material for magnesium batteries due to its non-toxicity, low-cost, zero-strain characteristics and long-term stability. Nevertheless, the application of LTO in a magnesium full cell has been rarely investigated. Herein, we give a proof of concept for the feasibility of LTO as anode in full magnesium ion batteries, which might prevent the passivation of metallic Mg anodes. Mg2+ was electrochemically inserted into LTO prior to cycling against a sulfur-based cathode material, i.e. sulfurated poly(acrylonitrile), SPAN, resulting in stable cycle performance with 800 mAh/gS at 0.3C and high-rate capability.

VERTICAL JUMPING PERFORMANCE RELATES TO SPRINTING PERFORMANCE OVER SHORT DISTANCES AND DIFFERENT SECTIONS

A high level of sprinting performance is relevant in various sports. Because of the transition of movement patterns in different sprint sections there is a shift in the relevance of speed-strength of the knee and hip extensors, and stretch-shortening cycle performance seems conceivable. Fifty-six physical education students (23.70 ± 3.00 years, 176.9 ± 8.10cm, 74.20 ± 10.30kg) were investigated. They performed sprints up to 30m in which different sections were analyzed and vertical jumps (squat jump, countermovement jump, drop jump from different dropping heights). Vertical jumping tests in squat jump and countermovement jump revealed mean values of 31.95 ± 6.56cm and 34.28 ± 7.47cm, respectively, while the drop jumps showed mean RSI values between 155.11 ± 36.77 and 168.24 ± 36.29 dependent on the dropping height. The sprint test showed a mean performance of 4.464 ± .343s (30m). The correlational analysis showed significant correlations (p < .01) for vertical jumping height with all sprinting sections (r = −.652 to −.834). Drop jump performance also showed significant correlations (p < .01) with all the sections (r = −.379 to −.594). The results let us hypothesize that the observed sample generated similar ground-reaction forces in the sprint and drop jump from a height of 40 cm.

Synthesis of Fe2+ Substituted High-Performance LiMn1−xFexPO4/C (x = 0, 0.1, 0.2, 0.3, 0.4) Cathode Materials for Lithium-Ion Batteries via Sol-Gel Processes

A series of carbon-coated LiMn1−xFexPO4 (x = 0, 0.1, 0.2, 0.3, 0.4) materials are successfully constructed using glucose as carbon sources via sol-gel processes. The morphology of the synthesized material particles are more regular and particle sizes are more homogeneous. The carbon-coated LiMn0.8Fe0.2PO4 material obtains the discharge specific capacity of 152.5 mAh·g−1 at 0.1 C rate and its discharge specific capacity reaches 95.7 mAh·g−1 at 5 C rate. Iron doping offers a viable way to improve the electronic conductivity and lattice defects of materials, as well as improving transmission kinetics, thereby improving the rate performance and cycle performance of materials, which is an effective method to promote the electrical properties.

Investigation on Structural and Electrochemical Properties of Olivine-Structured LiMn1-xFexPO4/C Cathode Materials Based on First-Principles Calculation

Currently, LiMnPO4 is a highly prevalent cathode material in lithium-ion batteries. However, its low conductivity and Li+ diffusion rate limit its practical application. To overcome these inherent defect, we have modified its properties by doping Fe at the Mn site. In the LiMn1-xFexPO4 system, the total density of states of electrons near the Fermi level and the energy band of the Fermi surface are obtained by first-principles calculation. The adjustment of the energy band width immediately influences the electronic conductivity of LiMn1-xFexPO4 system, which is positively related to the electrochemical performance. According to the results of first-principles calculation, we speculated that x=1/4 was the optimal doping concentration. Then, the LiMn1-xFexPO4/C systems were compounded by hydrothermal method to verify the first-principles’ hypothesis. The electrochemical tests show that the LiMn3/4Fe1/4PO4/C material has the best cycle performance and rate performance. At the condition of 0.05 C rate, this material possesses an initial discharge capacity of 142.5 mAh/g. with the capacity retention maintained 93.9% after 100 cycles. The theoretical calculation in consistent with the experimental findings, which accounts for the fact that the first-principles strategy is very effective in the research and development of lithium-ion batteries.