Eliminating Graphite Exfoliation with an Artificial Solid Electrolyte Interphase for Stable Lithium-Ion Batteries.

Although graphite materials with desirable comprehensive properties dominate the anode market of commercial lithium-ion batteries (LIBs), their low capacity during fast charging precludes further commercialization. In the present work, natural graphite (G) is reported not only to suffer from low capacity during fast charging, but also from charge failure after many charging cycles. Using different characterization techniques, severe graphite exfoliation, and continuously increasing solid electrolyte interphase (SEI) are demonstrated as reasons for the failure of G samples. An ultrathin artificial SEI is proposed, addressing these problems effectively and ensuring extremely stable operation of the graphite anode, with a capacity retention of ≈97.5% after 400 cycles at 1 C. Such an artificial SEI modification strategy provides a universal approach to tailoring and designing better anode materials for next-generation LIBs with high energy densities.

Labilibacter sediminis sp. nov., isolated from marine sediment.

A Gram-stain-negative, rod-shaped and facultatively anaerobic strain, designated CG51T, was isolated from marine sediment collected from a coastal area in Weihai, PR China. Strain CG51T grew at 4-37 °C (optimum, 28-30 °C), with 1.0-6.0 % (w/v) NaCl (2.0-3.0 %) and at pH 6.0-8.5 (pH 7.0-7.5). The predominant fatty acids were iso-C15 : 0, anteiso-C15 : 0 and iso-C14 : 0. Major polar lipids included an unidentified lipid and a phospholipid. The respiratory quinone was MK-7 and the genomic DNA G+C content was 35.9 mol%. The results of phylogenetic analysis based on 16S rRNA gene sequences placed strain CG51T in the genus Labilibacter with the close relatives being Labilibacter marinus Y11T and Labilibacter aurantiacus HQYD1T, exhibiting 96.5 and 96.3 % 16S rRNA pairwise similarity, values which are clearly below the 98.7 % threshold value recommended for species demarcation. Based on the phylogenetic, physiological, chemotaxonomic and genetic data, strain CG51T represents a novel species within the genus Labilibacter, for which the name Labilibacter sediminis sp. nov. is proposed. The type strain is CG51T (=MCCC 1K03739T=JCM 33138T).

Accelerating O-Redox Kinetics with Carbon Nanotubes for Stable Lithium-Rich Cathodes.

Lithium-rich cathodes (LRCs) show great potential to improve the energy density of commercial lithium-ion batteries owing to their cationic and anionic redox characteristics. Herein, a complete conductive network using carbon nanotubes (CNTs) additives to improve the poor kinetics of LRCs is fabricated. Ex situ X-ray photoelectron spectroscopy first demonstrates that the slope at a low potential and the following long platform can be assigned to the transition metal and oxygen redox, respectively. The combination of galvanostatic intermittent titration technique and electrochemical impedance spectroscopy further reveal that a battery with CNTs exhibited accelerated kinetics, especially for the O-redox process. Consequently, LRCs with CNTs exhibit a much better rate and cycling performance (≈89% capacity retention at 2 C for over 200 cycles) than the Super P case. Eventually, TEM results imply that the improved electrochemical performance of the CNTs case also benefits from its more stable bulk and surface structures. Such a facile conductive additive modification strategy also provides a universal approach for the enhancement of the electron diffusion properties of other electrode materials.