One pot synthesis of ordered mesoporous carbon–silica–titania with parallel alignment against graphene as advanced anode material in lithium ion batteries

Nitrogen-Doped Carbon-Encapsulated Ordered Mesoporous SiOx as Anode for High-Performance Lithium-Ion Batteries

SiO_x (0<x<2) has been broadly investigated as a promising anode in lithium-ion batteries (LIBs) due to its high theoretical capacity, low cost, and proper working voltage. Nevertheless, its practical application is hindered by volume expansion during the lithiation process and low electrical conductivity, resulting in rapid capacity decay. Herein, we designed a core-shell structured nitrogen-doped carbon-encapsulated ordered mesoporous SiO_x composite (SiO_x @NC) using 3-aminophenol-formaldehyde (3-AF) as carbon and nitrogen precursor, tetraethyl orthosilicate (TEOS) as the silica precursor, and cationic surfactant cetyltrimethylammonium bromide (C₁₆ TAB) as the mesoporous template. The obtained composite electrode not only can effectively reduce the volume expansion, but also can effectively improve electronic conductivity and further enhance the charge and ion transfer kinetics. Benefiting from the unique structural merits, the obtained SiO_x @NC-2 delivers a high reversible capacity of 602.4 mAh g^-1 at 0.1 A g^-1 after 100 cycles and long-term cyclability (maintain 426.1 mAh g^-1 over 1000 cycles at 1 A g^-1 ).

The Development of Graphene/Silica Hybrid Composites: A Review for Their Applications and Challenges

Graphene and silica are two materials that have wide uses and applications because of their unique properties. Graphene/silica hybrid composite, which is a combination of the two, has the good properties of a combination of graphene and silica while reducing the detrimental properties of both, so that it has promising future prospects in various fields. It is very important to design a synthesis method for graphene/silica composite hybrid materials to adapt to its practical application. In this review, the synthesis strategies of graphene, silica, and hybrid graphene/silica composites such as hydrothermal, sol-gel, hydrolysis, and encapsulation methods along with their results are studied. The application of this composite is also discussed, which includes applications such as adsorbents, energy storage, biomedical fields, and catalysts. Furthermore, future research challenges and futures need to be developed so that hybrid graphene/silica composites can be obtained with promising new application prospects.

Thermal Decomposition Study on Li2O2 for Li2NiO2 Synthesis as a Sacrificing Positive Additive of Lithium-Ion Batteries

Herein, thermal decomposition experiments of lithium peroxide (Li₂O₂) were performed to prepare a precursor (Li₂O) for sacrificing cathode material, Li₂NiO₂. The Li₂O₂ was prepared by a hydrometallurgical reaction between LiOH·H₂O and H₂O₂. The overall reaction during annealing was found to involve the following three steps: (1) dehydration of LiOH·H₂O, (2) decomposition of Li₂O₂, and (3) pyrolysis of the remaining anhydrous LiOH. This stepwise reaction was elucidated by thermal gravimetric and quantitative X-ray diffraction analyses. Furthermore, over-lithiated lithium nickel oxide (Li₂NiO₂) using our lithium precursor was synthesized, which exhibited a larger yield of 90.9% and higher irreversible capacity of 261 to 265 mAh g^-1 than the sample prepared by commercially purchased Li₂O (45.6% and 177 to 185 mAh g^-1, respectively) due to optimal powder preparation conditions.