Among all potential application fields of graphene, most important are still the electrochemical energy-storage devices, in particular the Li-ion batteries (LIB). Despite of all the efforts, the performance of the graphene-based Li-ion batteries is still far from satisfactory, considered their insufficient electrical capacity, rate performance and long-term stability (1). In the present work, we present the technique allowing the production of hierarchical graphene-based composite aerogels as binder-free anodes for the ultra-long-life Li-ion batteries (LIBs). Our approach is to increase an active area of the composite aerogel for the Li-ion uptake (or adsorption)by the introduction of spacers between the graphene sheets. The spacers are the MoxSy particles of three different size ranges: sub-nanometer (iii), a few nanometers (ii) and several hundreds of nanometer large amorphous carbon balls (i) filled with nanometer-sized MoxSy (see schematic in Figure 1). The incorporation of these poly-dispersed particles as spacers between the graphene sheets results in the hierarchically porous aerogel. Such structures as anodes in LIBs possess high capacity, 1069 mAh/g at 0.35 A/g, rate performance, 425 mAh/g at 10 A/g and 304 mAh/g at 50 A/g, and show ultra-long stability.
In the present work, MoxSy-particle loaded aerogels before and after the Li-ion uptake were studied by HRTEM / HRSTEM. Morphological and elemental analyses of the particle populations were performed (Figure 2). Moreover, all three groups of the spacers were analyzed for their spatial arrangement in relationship to graphene sheets by HRTEM and HRSTEM tomography, revealing the fully homogeneous spatial distribution of two groups of the small-sized clusters on the sheets and the hierarchical nature of the largest spacers consisting of the polymer balls uniformly filled with the small clusters. TEM analyses confirmed that all three kinds of the spacers are very effective in the preventing the graphene sheets from coalescence. Both, graphene sheets and the spacers can intake Li-ion, contributing to the charge-discharge cycles and are as such responsible for the long-life electrochemial performance.
- J. Liu, Charging graphene for energy, Nat. Nanotechnol.2014, 9, 739-741.
To cite this abstract:Alla Sologubenko, Guobo Zeng, Elena Tervoort, Fabian Gramm, Markus Niederberger; 3D-TEM studies of hierarhical graphene-composite aerogels for ultra-long-life Li-ion batteries. The 16th European Microscopy Congress, Lyon, France. https://emc-proceedings.com/abstract/3d-tem-studies-of-hierarhical-graphene-composite-aerogels-for-ultra-long-life-li-ion-batteries/. Accessed: October 29, 2020
EMC Abstracts - https://emc-proceedings.com/abstract/3d-tem-studies-of-hierarhical-graphene-composite-aerogels-for-ultra-long-life-li-ion-batteries/