New Progress in Structural Design of Electrode Materials for Lithium-ion Battery

Electrode materials are accompanied by volumetric expansion/contraction during the inlay / delithium process, and this volumetric effect often leads to material fragmentation failure. Therefore, the structure stability of the electrode material during the charging and discharging cycle has a vital influence on the battery capacity, doubling rate and cycle life.

Based on the phenomenon that Silicon dioxide(SiO2) can be used as a filler to improve the mechanical properties of composite materials, the Niuchunming team of Xi'an Jiaotong University Electric School designed and successfully prepared a porous SiO2 reinforced Sb/C fiber composite material. The fibrous structures of Silicon source(ethyl silicate), antimony source(antimony trichloride) and carbon source(polyethylene pyrrolidone) were prepared by electrostatic spinning method. The unique structures of SiO2 and Sb nanoparticles coated with porous carbon fibers were formed by thermal treatment. The introduction of SiO2 greatly enhances the overall structural stability of the fiber. As a negative electrode material for lithium ion batteries, the resulting SiO2 / Sb/C-porous fiber electrodes showed excellent electrochemical properties in both semi-battery and full-battery tests. Carbon fiber not only improves the conductivity of the electrode material, but also its porous structure effectively eliminates the volume changes of SiO2 and Sb during the inlay / delithium process. The structural stability of the material in the process of inlay / delithium was further revealed by in situ and non-in situ electron microscopy. The idea of structural enhancement of electrode materials proposed in this work is that the SiO2 enhancement effect(Silica-Reinforce Effect) is used to synchronously achieve the double improvement of electrode structural stability and lithium storage performance, and the method has universality(Materials Today Energy 2016, 1 -- 2, 24-32; Nanoscale 2016, 8,7595-7603).

The results of the study were published online under the title "Encapsulation Silica/Antimony into Porous Electric Carbon Carbon Nanofibers with Just Robust Quality For High-Eficience" online. The authoritative International Journal ACS Silicon Storm has an impact on factor 1342. The electrical school of Xi'an Jiaotong University is the first completion unit of the paper, and Wanghongkang is the first author and communication author of the paper. The collaborators include Professor Mi Shaobo of the School of Telecommunications of Xi'an Jiaotong University, Professor Zhangqiaobao of Xiamen University and Professor Andrew Rogach of City University of Hong Kong.

The research work was supported by the National Natural Science Foundation, Xi'an Jiaotong University's "Youth Top Talent Support Program", the Tang Zhongying Foundation, the Young Teacher Support Program of the School of Electrical Engineering, the State Key Laboratory of Electrical Insulation of Electric Equipment, and the Xi'an Jiaotong University Analytical Testing and Sharing Center.

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