Advanced anode material designs utilizing dual phase alloy systems like Si/FeSi2 nano-composites show great potential to decrease the capacity degrading and improve the cycling capability for Lithium (Li)-ion batteries. Here, we present a multi-scale characterization approach to understand the (de-)lithiation and irreversible volumetric changes of the amorphous silicon (a-Si)/crystalline iron-silicide (c-FeSi2) nanoscale phase and its evolution due to cycling, as well as their impact on the proximate pore network. Scattering and 2D/3D imaging techniques are applied to probe the anode structural ageing from nm to μm length scales, after up to 300 charge-discharge cycles, and combined with modeling using the collected image data as an input. We obtain a quantified insight into the inhomogeneous lithiation of the active material induced by the morphology changes due to cycling. The electrochemical performance of Li-ion batteries does not only depend on the active material used, but also on the architecture of its proximity.

Our study demonstrates that differences of the formalin composition have substantial effects on MRI signal characteristics after fixation, which can explain the divergence of reported relaxation times beyond the effect of differences in formalin concentration. Magn Reson Med 79:1111-1115, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Energy storage will be according to the European Energy Storage Technology Development Roadmap (EASE/EERA) towards 2030 [1], of high importance for worldwide climate energy objectives as it has the potential to cover the entire energy value chain. Especially lithium-based technology will play an important role in this context [1]. However, lithium (Li)-ion batteries still have to struggle with several shortcomings, mainly due to material deficiencies, leading to a limited lifetime and the still high energy costs per kWh. In order to conquer these shortcomings, the use of novel material approaches and processing steps need to be investigated, which are also suitable for industrial applications. A breakthrough in this manner can be achieved e.g. by the use of, (1) carbon-based materials, (2) silicon(Si)-based material and (3) cost efficient electrode and cell manufacturing processes. However, still several scientific and technological questions for silicon based lithium-ion batteries e.g. the impact of various loading cycles, which reduce the life time of batteries and components and of storage capacity, are open. In this context especially the microstructure of the electrode material plays an important role since it has big impact on the performance on the battery. Therefore, experimental methods which include 2D and 3D from the electrode material over the mm to the nm scale as well as accurate image analyzing algorithm are necessary.In this work we develop a characterization toolbox suitable to analyze the micro structure of pristine Si-based anode material which is relevant for future Li-ion batteries used in industrial related storage solutions. This comprises (1) the measurement of the microstructure by using focused ion beamscanning electron microscopy (FIB-SEM) and X-ray computed tomography (XCT) to cover the length scales from mm to nm including 2D and 3D information, (2) the development of suitable image analysis algorithm to obtain accurate results regarding the microstructure of the electrode, and (3) the validation of the data by comparing FIB-SEM and XCT results.The active region of the sample is basically defined by a graphite matrix, a binder and the distributed Si particles within the graphite/binder matrix. The electrode material is manufactured by mixing the components directly and cast them for instance on a copper foil. Samples are then prepared for the individual methods. In addition we compare different samples having different weight percentage of the Si phase. The XCT system has a focal spot size of 800 nm and gives the possibility to measure for these particular samples a Voxel size V down to about V x = V y = V z = 700 nm. This gives the opportunity to gain 3D information between the mm to the m scale. For the m to the nm scale we use FIB-SEM. For the analysis of the 2D and 3D structural data we discuss the use of the commercially available imaging software Avizo ® from FEI and Python. For the segmentation of the different phases of the electrode material we are using an approach to ite...

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High-density silicon composite anodes show large volume changes upon charging/discharging triggering the reformation of the solid electrolyte interface (SEI), an interface initially formed at the silicon surface. The question remains how the reformation process and accompanied material evolution, in particular for industrial up-scalable cells, impacts cell performance. Here, we develop a correlated workflow incorporating X-ray microscopy, field-emission scanning electron microscopy tomography, elemental imaging and deep learning-based microstructure quantification suitable to witness the structural and chemical progression of the silicon and SEI reformation upon cycling. The nanometer-sized SEI layer evolves into a micron-sized silicon electrolyte composite structure at prolonged cycles. Experimental-informed electrochemical modelling endorses an underutilisation of the active material due to the silicon electrolyte composite growth affecting the capacity. A chemo-mechanical model is used to analyse the stability of the SEI/silicon reaction front and to investigate the effects of material properties on the stability that can affect the capacity loss.