Nanocrystals from Oriented-Attachment for Energy Applications by Weidong He Kechun Wen & Yinghua Niu

Author:Weidong He, Kechun Wen & Yinghua Niu
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

Fig. 3.6 a Rate-performances of Co0.85Se nanosheets and microspheres, (b, c) Cyclic performances at the current densities of b 200 mA g−1 and c 500 mA g−1, and d EIS spectra recorded at 3.0 V.

Adopted from Ref. [10]

3.4 Oriented-Attachment Nanocrystals as Cathodes of LIBs

Rangappa et al. [29] synthesized ultrathin Li2MSiO4 (M = Mn, Fe) nanosheets by employing a one-pot supercritical fluid method. The small Li2MSiO4 nuclei first assemble to form small platelike particles and nanoplates, followed by formation of NSs via OA growth and/or Ostwald Ripening mechanism. The solvent ratio (ethanol/water) plays an important role in determining the growth process and morphologies of Li2MSiO4 nanosheets. As shown in Figs. 3.7 and c, after coating with conductive polymer (5 wt%) and MWCNT (5 wt%), Li2MnSiO4 and Li2FeSiO4 NSs deliver high specific capacities of 350 mAh/g and 340 mAh/g at 45 °C, respectively, which are much higher than those of spherical-shaped Li2MnSiO4 (145 mAh/g) and Li2FeSiO4 (105 mAh/g) structures. In addition, Figs. 3.7b, d show the excellent stability and reversibility of Li2MSiO4 NS electrodes. After 20 cycles, both samples still have a ~85% capacity retention at 1/50 C. These enhanced properties mainly arise from the NSs structures with large surface area and nanoscale thickness, leading to excellent mechanical and electrical properties.

Fig. 3.7Charge and discharge profiles of first and second cycles. a Li2FeSiO4, c Li2MnSiO4 samples measured at 45 °C at 0.02 C. b, d Cyclic performances of Li2FeSiO4 and Li2MnSiO4 samples, respectively.

Adopted from [29]

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