Ball-in-ball composite nanospheres show favorable sodiation evolution

How can uniquely structured nanoparticles improve performance of silicon-based sodium-ion battery anode materials?

Fei-Hu Du, Yong Wang, and their colleagues at Shanghai University and Shanghai Jiao Tong University published work using their Hummingbird Scientific in-situ biasing nano-manipulator TEM sample holder to perform in-situ battery performance testing on ball-in-ball polypyrrole and amorphous silicon hollow nanospheres (a-Si@void@PPy) synthesized by sodiothermic reduction. The particles were characterized using scanning/transmission electron microscopy (S/TEM) with energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD).

a) Schematic diagram of the synthesis route for a-Si@void@PPy composite nanosphere. b–d) SEM images of (b) the MHSiO2, (c) a-Si, and (d) a-Si@void@PPy e–g) TEM images of (e) the MHSiO2, (f) a-Si, and (g) a-Si@void@Ppy composite. h) Dark field STEM image of the a-Si@void@PPy composite. i) EDX mappings of C, N, and Si in the a-Si@void@PPy composite. j) EDX spectrum of the a-Si@void@PPy composite. Copyright 2022 Wiley-VCH GmbH

Charge-discharge tests and cyclic voltammetry were performed on the nanoparticles alongside in-situ sodiation inside of a nanobattery assembly under TEM. Electrochemical testing indicated excellent rate performance, cycle life, and large reversible anodic capacities. The porous a-Si combined with the shell gap accommodated the volume expansion of a large influx of electrolyte, facilitating Li+ transport, while the PPy shell increased overall conductivity and provided partial shielding of the electrode from electrolyte contact. The range of acceptable void thicknesses (25-91 nm) was determined by finite element modeling. The team demonstrated the promise of the ball-in-ball nanoparticle synthesis technique for amorphous Si-based sodium-ion battery (SIB) anode design, relying on the Hummingbird Scientific biasing nano-manipulator TEM sample holder for their in-situ sodiation experiments.

TEM video showing time lapse of the sodiation of a-Si@void@PPy nanosphere. Copyright 2022 Wiley-VCH GmbH

Reference: Fei-Hu Du, Ling Zhang, Yun-Cheng Tang, Shang-Qi Li, Yu Huang, Le Dong, Qianqian Li, Hong Liu, Dong Wang, and Yong Wang, Advanced Materials Interfaces 9 (9) 2102158 (2022) DOI: 10.1002/admi.202102158

Full paper Copyright © 2022 Wiley-VCH GmbH


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