Nitrogen doped carbon layer of Li2MnSiO4 with enhanced electrochemical performance for lithium ion batteries

Diammonium Hydrogen Citrate-Assisted Spray Pyrolysis Synthesis of Nanostructured LiCoPO4 Microspheres as High-Voltage Cathode Material for Lithium-Ion Batteries

Nanostructured LiCoPO4 (LCP) microspheres were successfully synthesized by one-step spray pyrolysis, adding an appropriate amount of diammonium hydrogen citrate (DHC) additive to the precursor solution. Comprehensive physical characterization confirmed that the obtained LCPs exhibited a desirable orthorhombic olivine structure with nanostructured morphology and a significant increase in specific surface area. This enhancement was attributed to the dispersion effect due to the carboxyl group and the evolution of the ammonium group of DHC during the pyrolysis process. The resultant LCP delivered a high initial discharge capacity of 132 mA h g-1 with 63.3% capacity retention (vs 103 mA h g-1 and 37.1% of bare-LCP) after 50 cycles at 0.1 C using the conventional electrolyte. Moreover, the electrochemical performance showed additional enhancement when a fluorinated electrolyte was introduced, resulting in initial and 50th discharge capacities of 141 and about 100 mA h g-1, respectively, at 0.1 C.

Synthesis and Characterization of Li2Mn0.8Ni0.2SiO4/Mn3O4 Nanocomposite for Photocatalytic Degradation of Reactive Blue (RB5) Dye

This study successfully synthesized Li2MnSiO4/Mn3O4 (LMS/M3) and Li2Mn0.8Ni0.2SiO4/Mn3O4 (LMNS/M3) nanocomposites in a two-step method first, by preparing Mn3O4 (M3) nanoparticles through a hydrothermal method and second, by synthesizing Li2MnSiO4 (LMS) and Li2Mn0.8Ni0.2SiO4 (LMNS) by ethylene diamine tetra-acetic assisted sol–gel method. In the last method, the two nanoparticles are mixed by hand-milling to form nanocomposites. Synthesized nanoparticles were characterized using X-ray diffraction, Fourier-transform infrared, Raman spectra, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, Brunauer–Emmett–Teller surface area, pL and UV–vis spectra measurements. The nanocomposite presents a well-developed orthorhombic crystal structure with a Pmn21 space group. BET surface area measurements indicate that all the prepared materials are mesoporous. The photocatalytic activity of M3, LMS, LMNS, (LMS/M3), and (LMNS/M3) was investigated by the photocatalytic degradation of reactive blue 5 (RB5) under UV light irradiation using a homemade photoreactor. The maximum photodegradation was achieved at optimal pH 4 and photocatalyst dose 0.005 g/50 ml dye. Higher stability for dye degradation efficiency was attained for the LMS and LMNS nanomaterials and LMS/M3 and LMNS/M3 nanocomposites than M3 to photocatalytic activity. The photocatalyst is readily recoverable and shows excellent stability even after three cycles. The photocatalytic degradation for RB5 followed first-order kinetics.

Graphical Abstract

Silkworm Protein-Derived Nitrogen-Doped Carbon-Coated Li[Ni0.8Co0.15Al0.05]O2 for Lithium-Ion Batteries

Li[Ni0.8Co0.15Al0.05]O2 (NCA) is a cathode material for lithium-ion batteries and has high power density and capacity. However, this material has disadvantages such as structural instability and short lifespan. To address these issues, herein, we explore the impact of N-doped carbon wrapping on NCA. Sericin, an easily obtained carbon- and nitrogen-rich component of silk cocoons, is utilized as the precursor material. The electrochemical performance evaluation of N-doped carbon-coated NCA shows that the capacity retention of 0.3 NC@NCA at 1C current density is 69.83% after 200 cycles, which is about 19% higher than the 50.65% capacity retention of bare NCA. The results reveal that the sericin-resultant N-doped carbon surface wrapping improves the cycling stability of NC@NCA.

Characterization of lithium zinc titanate doped with metal ions as anode materials for lithium ion batteries

With the aim of improving the ionic and electronic conductivities of Li₂ZnTi₃O₈ for high performance lithium ion battery applications, Li₂Zn_0.9M_0.1Ti₃O₈ (M = Li⁺, Cu²⁺, Al³⁺, Ti⁴⁺, Nb⁵⁺, Mo⁶⁺) compounds are successfully fabricated using facile high temperature calcination at 800 °C. Physical characterization and lithium ion reversible storage demonstrate that Zn-site substitution by multivalent metal ions is beneficial for improving the migration rate of ions and electrons of Li₂ZnTi₃O₈. X-ray diffraction analysis and scanning electron microscopy reveal that the crystal structure and microscopic morphology of bare Li₂ZnTi₃O₈ do not change by introducing a small amount of foreign metal ions. As a result, Li₂Zn_0.9Nb_0.1Ti₃O₈ retains a reversible capacity as high as 198 mA h g^-1 at the end of the 500th cycle among all samples. Even when cycled at high temperatures, Li₂Zn_0.9Nb_0.1Ti₃O₈ still maintains excellent reversible discharge capacities of 210 mA h g^-1 and 196 mA h g^-1 at 1000 mA g^-1 for the 100th cycle at 50 °C and 60 °C, respectively. All the conclusions indicate that Li₂Zn_0.9Nb_0.1Ti₃O₈ is a high-performance anode material for large-scale energy storage devices.

A bee pupa-infilled honeycomb structure-inspired Li2MnSiO4 cathode for high volumetric energy density secondary batteries

Emerging power batteries with both high volumetric energy density and fast charge/discharge kinetics are required for electric vehicles. The rapid ion/electron transport of mesostructured electrodes enables a high electrochemical activity in secondary batteries. However, the typical low fraction of active materials leads to a low volumetric energy density. Herein, we report a novel biomimetic "bee pupa infilled honeycomb"-structured 3D mesoporous cathode. We found previously the maximum active material filing fraction of an opal template before pinch-off was about 25%, whereas it could be increased to ∼90% with the bee pupa-infilled honeycomb-like architecture. Importantly, even with a high infilling fraction, fast Li+/e- transport kinetics and robust mechanical property were achievable. As the demonstration, a bee pupa infilled honeycomb-shaped Li2MnSiO4/C cathode was constructed, which delivered a high volumetric energy density of 2443 W h L-1. The presented biomimetic bee pupa infilled honeycomb configuration is applicable for a broad set of both cathodes and anodes in high energy density batteries.