Recently, the internationally renowned journals Advanced Materials (IF = 21.95) and Advanced Energy Materials (IF = 21.875) have successively published the team of Professor Ji Xiaobo from the School of Chemistry and Chemical Engineering of Central South University on the sodium selenide negative electrode materials. Series of research work. Professor Ji Xiaobo is the author of the paper, and the 2016 doctoral student Ge Peng is the first author of the paper.
Professor Ji Xiaobo's team has long been committed to the research of new battery materials. It is found that the conversion reaction, which is one of the three major reaction mechanisms, has a volume expansion smaller than the alloying reaction and larger than the sodium storage capacity of the embedded reaction. It is currently considered as a new battery material system with great potential. Such materials mainly include metal oxides, sulfides, selenides, phosphides, etc. Due to the toxicity of the raw materials of phosphides and the limitation of the synthesis methods, the main conversion materials are mainly concentrated to the metal-based sixth main group compounds. Among them, due to the strong electronic conductivity of Se element (1 × 10-5 S m-1) and weak electronegativity (2.5), metal selenide has the potential to have excellent charge-discharge ratio capacity. And cycle stability.
Professor Ji Xiaobo's team has made new progress in designing and regulating the interface characteristics of metal selenium-based materials and carbon substrates. A self-assembly method is designed to synthesize a branched nickel carbonate (Ni-Pr), and a pyrrole monomer is adsorbed therein by a large specific surface area thereof for polymerization. The use of Se elementality and the Kirkendall effect at high temperatures successfully produced a carbon-coated multi-stage hollow structure. The system successfully introduces the metal oxygen-carbon bond and the derivatized double carbon layer structure, which effectively improves the reaction reversibility of the material, alleviates the volume expansion of the material, and deepens the depth of the electrochemical reaction. It exhibits excellent performance in the field of sodium ion energy storage, and this work has important guiding significance for the design and derivation of metal-based materials. The research results were recently published in Advanced Energy Materials (2018, DOI: 10.1002/adma.201803035) (IF = 21.875).
In addition, the team found that the iron-based Prussian blue structure has a wide range of raw materials and simple production processes, but the material itself has internal interstitial crystallization water and relatively weak redox power to Fe2+/Fe3+, resulting in such materials. Cyclic stability and rate performance are poor. Partial iron-based elements are replaced by cations (cobalt, nickel, manganese) for a series of effective regulation of crystallinity, particle size, and electrochemical properties of Prussian blue-like materials. Thanks to excellent physicochemical stability, enhanced kinetic coefficients and “zero strain†structure, the prepared Ni-Fe PBAs can still maintain a capacity of 81 mAh at a current density of 1.0 A g-1. -1. In addition, the double-carbon core-shell structure nickel-iron-based selenide is further derivatized by pyrolytic selenization, exhibiting excellent cycle stability and rapid charge and discharge capability. The nickel-based Prussian blue and the corresponding selenide derived as the positive and negative materials were assembled to correspond to the all-electric system, exhibiting a superior charge-discharge specific capacity of 302.2 mAh g-1 (1.0 A g-1). The research results were recently published in Advanced Materials (2018, DOI: 10.1002/adma.201806092) (IF = 21.95).
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