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All‐solid‐state batteries (ASSBs) with silicon anodes are promising candidates to overcome energy limitations of conventional lithium‐ion batteries. However, silicon undergoes severe volume changes during cycling leading to rapid degradation. In this study, a columnar silicon anode (col‐Si) fabricated by a scalable physical vapor deposition process (PVD) is integrated in all‐solid‐state batteries based on argyrodite‐type electrolyte (Li6PS5Cl, 3 mS cm−1) and Ni‐rich layered oxide cathodes (LiNi0.9Co0.05Mn0.05O2, NCM) with a high specific capacity (210 mAh g−1). The column structure exhibits a 1D breathing mechanism similar to lithium, which preserves the interface toward the electrolyte. Stable cycling is demonstrated for more than 100 cycles with a high coulombic efficiency (CE) of 99.7–99.9% in full cells with industrially relevant areal loadings of 3.5 mAh cm−2, which is the highest value reported so far for ASSB full cells with silicon anodes. Impedance spectroscopy revealed that anode resistance is drastically reduced after first lithiation, which allows high charging currents of 0.9 mA cm−2 at room temperature without the occurrence of dendrites and short circuits. Finally, in‐operando monitoring of pouch cells gave valuable insights into the breathing behavior of the solid‐state cell.

Polysulfide shuttling is a crucial factor in lithium sulfur batteries responsible for capacity fading and degradation. Liquid phase adsorption in combination with nuclear magnetic resonance and X‐ray photoelectron spectroscopy are used to elucidate and quantify polysulfide retention in typical porous cathode materials used in lithium sulfur batteries without cell assembly to achieve a more fundamental understanding of liquid phase adsorption phenomena as a responsible mechanism for polysulfide retention. The individual impact of each pore size increment is quantified on the polysulfide adsorption (PSA). Ultramicropores show eight times higher PSA (1.48 mmol cm−3) than mesopores. Strong heteroatom‐doped ultramicropores show even stronger interactions with polysulfides leading to 25 times higher adsorption compared to hydrophobic mesopores. These findings allow to precisely tailor pore structure and heteroatom distribution of cathode materials for next generation lithium sulfur batteries with prolonged cycle life and reduced capacity fading.

Si is a promising anode material for Li storage due to its high theoretical specific capacity surpassing 4200 Ah/kg. Si based anodes exhibit an extreme instability upon electrochemical incorporation of Li given the accompanied large volume expansion of about 400%. We show innovative anode assemblies composed of a forest of free standing Si nanowires conformally integrated on carbon meshes. The morphology of silicon nanowires allows a volume expansion and compression lowering strain incorporation. In this paper, we demonstrate the utilization of SiNW grown on top of a current collector made of a carbon fiber network. This leads to an increase of stability of Si with a remaining effective capacitance above 2000 Ah/kg(Si) after 225 full charge/discharge cycles. This is significantly better compared to previous results shown in literature. The anodes are fabricated by a simple and inexpensive method promising for a transfer into industrial integration.

Vertical aligned carbon nanotube (CNT) films are promising candidates for electrode surfaces in super capacitors suitable for electric energy storage. The CNT films provide a matrix with low internal resistance and a directed pore system for fast ion diffusion, both being crucial for high power supercap devices. The contribution describes the deposition process and properties of multiwalled and single walled CNTs on various metallic substrates by thermal CVD. Up to 100 micron thick, well-aligned CNT films were obtained on Ni-substrates. For steel substrates CNT forests with heights up to 20 µm were observed. The influence of several parameters on the CNT morphology was investigated.

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One of the key challenges of the 21st century is the development of rechargeable energy-storage systems that can be coupled to renewable energy sources and for the use in consumer devices. Among them, rechargeable lithium batteries are very attractive candidates due to their high energy densities. One of the most promising next generation systems is the lithium-sulphur (Li-S) battery where sulphur as the cathode material accommodates a maximum of two lithium ions in a non-topotactical assimilation process and offers a theoretical capacity as high as 1672 mAh/g against Lithium significantly exceeding classical Li-ion devices based on intercalation. In addition, sulphur provides a broad operating temperature and an intrinsic protection mechanism against overcharging, which enhances the battery safety [1]. However, it is still associated with various drawbacks including the low electrical conductivity of elemental sulphur and the shuttling mechanism of polysulphides during charging hindering its practical use in these devices. In recent years, it was found that mesoporous carbon materials are very promising as conductive host structures for the active material [2]. Especially hierarchically structured carbon materials seem to be highly suitable due to their large specific surface areas that provide sufficient contact area/interface with the active material. In the present contribution, we report the synthesis and lithium-sulphur performance of two advanced mesoporous carbon structures. Carbide-derived carbon (CDC) mesofoams (designated as DUT-70) were prepared by nanocasting of mesocellular SiO2 foams with polycarbosilanes followed by pyrolysis and template removal. The extraction of the semi-metal atoms from the resulting silicon carbide mesofoams by use of hot chlorine gas leads to the formation of DUT-70 with very high specific surface areas of 2700 m2/g and total pore volumes up to 2.6 cm3/g [3]. It can be infiltrated with sulphur and host the active material in lithium-sulphur battery cathodes. Reversible capacities of 790 mAh/g are achieved at a current rate of C/10 after 100 cycles rendering DUT-70 as an ideal support material for this electrochemical energy storage application due to the strong encapsulation of the active material in the hierarchical pore system. Moreover, we report the synthesis of mesoporous carbon materials, so called Kroll-Carbons (KCs), which can be obtained by high-temperature chlorine treatment of TiO2/Carbon nanocomposites. The reductive carbochlorination selectively removes the template according to the equation TiO2 + 2 Cl2 + (2 + x) C -> TiCl4 + 2 CO + x C and meso- as well as micropores are inserted into the resulting porous carbon material. The mesopore size can be tailored in a wide range by using template particles of different size and high specific surface areas of 1980 m2/g coupled with total pore volumes up to 3.1 cm3/g are obtained. KCs prepared from a commercially available template material (Degussa P 25) show outstanding performance as sulphur host material in high capacity cathodes for lithium-sulphur batteries. Sulphur contents up to 72 wt% cause initial discharge capacities as high as 747 mAh/g and stable cycling with reversible capacities of more than 550 mAh/g (related to the mass of the cathode) [4]. [1] N. Jayaprakash, J. Shen, Surya S. Moganty, A. Corona, L. A. Archer: “Porous Hollow Carbon@Sulphur Composites for High-Power Lithium-Sulphur Batteries”, Angew. Chem. Int. Ed. 2011, 5904 . [2] X. Ji, K. Lee, L. F. Nazar: “A highly ordered nanostructured carbon-sulphur cathode for lithium-sulphur batteries”, Nat. Mater. 2009, 500 . [3] M. Oschatz, L. Borchardt, K. Pinkert, S. Thieme, M. R. Lohe, C. Hoffmann, M. Benusch, F. M. Wisser, C. Ziegler, L. Giebeler, M. H. Rümmeli, J. Eckert, A. Eychmüller, S. Kaskel: „Hierarchical Carbide-Derived Carbon Foams with Advanced Mesostructure as a Versatile Electrochemical Energy-Storage Material“, Adv. Energy Mater. Adv. Energy Mater. 2014, 4, 1. [4] M. Oschatz, S. Thieme, L. Borchardt, M. R. Lohe, T. Biemelt, J. Brückner, H. Althues, S. Kaskel: „A new route for the preparation of mesoporous carbon materials with high performance in lithium-sulphur battery cathodes”, Chem. Commun. 2013, 5832 .

Due to their high theoretical specific energy density and the low costs of sulfur, Lithium-sulfur (Li-S) batteries are of high interest as the storage of electric energy becomes more and more important. After several year of investigation, they still lack of a high cycling stability, which can be mainly ascribed to the formation of dendrites and particularly, to the so-called polysulfide (PS) shuttle mechanism. Therefore, the understanding of the latter and its possible inhibition is the aim of current research. Adding traces of LiNO3 to the electrolyte or using composite cathodes with additional polysulfide reservoirs seems to prolong the battery life.1,2 Other publications report on carbon host materials with specially designed porosity in order to avoid the polysulfide diffusion. Up to now, the detailed mechanism of the shuttle and the effect of PS reservoirs is not fully understood as previous studies concentrated more on electrochemical characterization of half-cells including other components, such as separator and anode.3 This study is focused on the liquid phase adsorption of stoichiometric and ex-situ synthesized polysulfides from a Li-S battery electrolyte on porous carbons to simulate a simplified Li-S cell environment. Several micro and meso and hierarchically structured porous carbons were investigated - both industrial reference materials and specially designed carbons. The latter are already electrochemically tested as carbon-sulfur cathode composite in Li-S cells. Li2Sx(x=4,6,8) were synthesized by stirring stoichiometric amounts of Lithium and sulfur in DOL/DME (1:1) at 70°C under Argon until the solution reached equilibrium condition. Subsequently, the porous carbons were added and the PS adsorption was monitored by UV/Vis spectroscopy. The influence of different carbon porosities on the adsorption properties of the polysulfides species was investigated. (1) Ji, X.; Evers, S.; Black, R.; Nazar, L. F. Nat. Commun. 2011, 2, 325. (2) Aurbach, D.; Pollak, E.; Elazari, R.; Salitra, G.; Kelley, C. S.; Affinito, J. J. Electrochem. Soc. 2009, 156, A694. (3) Evers, S.; Yim, T.; Nazar, L. F. J. Phys. Chem. C 2012, 116, 19653–19658.