Tailoring Pore Size and Polarity for Liquid Phase Adsorption by Porous Carbons

Adsorption is a versatile purification technique to selectively separate different peptide fractions from a mixture using mild operation conditions. Porous carbons are ideally suited to separate ACE-inhibiting dipeptides by combining tailored size exclusion and polarity selectivity. The desired peptide fraction is mostly hydrophobic and very small and should adsorb inside hydrophobic micropores. The second topic of this thesis is linked to energy storage. The lithium-sulfur battery is a promising alternative to common lithium-ion batteries with theoretical capacities of up to 1672 mAh g−1 sulfur. The second aim of this thesis is to conduct an in-depth investigation of polysulfides interacting with selected carbon materials in a simplified battery electrolyte environment. The focus of this study is laid on the impact of surface polarity and pore size distribution of the carbon to develop a quantitative correlation between polysulfide retention and porosity metrics. Both, the enrichment of ACE-inhibitors and the retention of polysulfides rely on liquid phase adsorption in porous materials, linking the above mentioned topics. This thesis not only aims to develop an enrichment process or to find a superior battery cathode but also strives to explore structure-property relationships that are universally valid. Understanding the complex interplay of pore size and polarity leading to selective interactions between pore wall and the adsorbed species is given a high priority

Mechanistic insights into the reversible lithium storage in an open porous carbon via metal cluster formation in all solid-state batteries

Porous carbons are promising anode materials for next generation lithium batteries due to their large lithium storage capacities. However, their highsloping capacity during lithiation and delithiation as well as capacity fading due to intense formation of solid electrolyte interphase (SEI) limit their gravimetric and volumetric energy densities. Herein we compare a microporous carbide derived carbon material (MPC) as promising future anode for all solid state batteries with a commercial high performance hard carbon anode. The MPC obtains high and reversible lithiation capacities of 1000 mAh g 1 carbon in half cells exhibiting an extended plateau region near 0 V vs. Li/Liþ preferable for full cell application. The well defined microporosity of the MPC with a specific surface area of >1500 m2 g 1 combines well with the argyrodite type electrolyte (Li6PS5Cl) suppressing extensive SEI formation to deliver high coulombic efficiencies. Preliminary full cell measurements vs. nickel rich NMC cathodes (LiNi0.9Co0.05Mn0.05O2) provide a considerably improved average potential of 3.76 V leading to a projected energy density as high as 449 Wh kg 1 and reversible cycling for more than 60 cycles. 7Li Nuclear Magnetic Resonance spectroscopy was combined with ex situ Small Angle X ray Scattering to elucidate the storage mechanism of lithium inside the carbon matrix. The formation of extended quasi metallic lithium clusters after electrochemical lithiation was revealed

Tailoring Pore Size and Polarity for Liquid Phase Adsorption by Porous Carbons

Adsorption is a versatile purification technique to selectively separate different peptide fractions from a mixture using mild operation conditions. Porous carbons are ideally suited to separate ACE-inhibiting dipeptides by combining tailored size exclusion and polarity selectivity. The desired peptide fraction is mostly hydrophobic and very small and should adsorb inside hydrophobic micropores. The second topic of this thesis is linked to energy storage. The lithium-sulfur battery is a promising alternative to common lithium-ion batteries with theoretical capacities of up to 1672 mAh g−1 sulfur. The second aim of this thesis is to conduct an in-depth investigation of polysulfides interacting with selected carbon materials in a simplified battery electrolyte environment. The focus of this study is laid on the impact of surface polarity and pore size distribution of the carbon to develop a quantitative correlation between polysulfide retention and porosity metrics. Both, the enrichment of ACE-inhibitors and the retention of polysulfides rely on liquid phase adsorption in porous materials, linking the above mentioned topics. This thesis not only aims to develop an enrichment process or to find a superior battery cathode but also strives to explore structure-property relationships that are universally valid. Understanding the complex interplay of pore size and polarity leading to selective interactions between pore wall and the adsorbed species is given a high priority

Tailoring Pore Size and Polarity for Liquid Phase Adsorption by Porous Carbons

Adsorption is a versatile purification technique to selectively separate different peptide fractions from a mixture using mild operation conditions. Porous carbons are ideally suited to separate ACE-inhibiting dipeptides by combining tailored size exclusion and polarity selectivity. The desired peptide fraction is mostly hydrophobic and very small and should adsorb inside hydrophobic micropores. The second topic of this thesis is linked to energy storage. The lithium-sulfur battery is a promising alternative to common lithium-ion batteries with theoretical capacities of up to 1672 mAh g−1 sulfur. The second aim of this thesis is to conduct an in-depth investigation of polysulfides interacting with selected carbon materials in a simplified battery electrolyte environment. The focus of this study is laid on the impact of surface polarity and pore size distribution of the carbon to develop a quantitative correlation between polysulfide retention and porosity metrics. Both, the enrichment of ACE-inhibitors and the retention of polysulfides rely on liquid phase adsorption in porous materials, linking the above mentioned topics. This thesis not only aims to develop an enrichment process or to find a superior battery cathode but also strives to explore structure-property relationships that are universally valid. Understanding the complex interplay of pore size and polarity leading to selective interactions between pore wall and the adsorbed species is given a high priority

Mechanochemistry-assisted synthesis of hierarchical porous carbons applied as supercapacitors

A solvent-free synthesis of hierarchical porous carbons is conducted by a facile and fast mechanochemical reaction in a ball mill. By means of a mechanochemical ball-milling approach, we obtained titanium(IV) citrate-based polymers, which have been processed via high temperature chlorine treatment to hierarchical porous carbons with a high specific surface area of up to 1814 m2 g−1 and well-defined pore structures. The carbons are applied as electrode materials in electric double-layer capacitors showing high specific capacitances with 98 F g−1 in organic and 138 F g−1 in an ionic liquid electrolyte as well as good rate capabilities, maintaining 87% of the initial capacitance with 1 M TEA-BF4 in acetonitrile (ACN) and 81% at 10 A g−1 in EMIM-BF4

Mechanochemistry-assisted synthesis of hierarchical porous carbons applied as supercapacitors

A solvent-free synthesis of hierarchical porous carbons is conducted by a facile and fast mechanochemical reaction in a ball mill. By means of a mechanochemical ball-milling approach, we obtained titanium(IV) citrate-based polymers, which have been processed via high temperature chlorine treatment to hierarchical porous carbons with a high specific surface area of up to 1814 m2 g−1 and well-defined pore structures. The carbons are applied as electrode materials in electric double-layer capacitors showing high specific capacitances with 98 F g−1 in organic and 138 F g−1 in an ionic liquid electrolyte as well as good rate capabilities, maintaining 87% of the initial capacitance with 1 M TEA-BF4 in acetonitrile (ACN) and 81% at 10 A g−1 in EMIM-BF4

Facile storage and release of white phosphorus and yellow arsenic

White phosphorus and yellow arsenic represent useful elemental sources for synthetic applications, but their poor stabilities make their storage highly challenging. Here, Scheer and colleagues encapsulate P4 and As4 molecules within porous activated carbons and demonstrate their use in subsequent chemical reactions

Nanomaterials for future generation Lithium-Sulphur batteries: Final report : collaborative project : subproject: Nanostructured carbons for carbon-sulfur nanocomposites : time of the project: From 01 May 2012 to 30 June 2015, reporting period: From 01 May 2012 to 30 June 2015

Elektromobilität verspricht ein großes Potential, aber weitere Innovationen sind nötig, um die Nachteile der Elektrofahrzeuge gegenüber Verbrennungsmotor betriebenen Fahrzeugen auszugleichen. Limitierend wirken sich vor allem die Kosten und die Energiedichte der Batterie aus. Letztere begrenzt im Wesentlichen die rein elektrische Reichweite der Elektrofahrzeuge. Lithium-Ionen-Batterien nach Stand der Technik erreichen ca. 200 Wh kg-1. Neue Batterien mit signifikant höherer Energiedichte wären ein großer Schritt, um die Elektromobilität massentauglich zu machen. Zukünftige Batteriegenerationen sind dabei eine große Chance für Europa den Technologievorsprung in Asien aufzuholen. Die Lithium-Schwefel-Technologie hat dabei das Potential, deutlich höhere Energiedichten zu erreichen und gleichzeitig Materialkosten zu senken. Im Rahmen des MaLiSu Projektes wurde ein signifikanter Beitrag zum fundamentalem Verständnis der Lithium-Schwefel Batteriemischung geleistet. Kohlenstoffmaterialien agieren als leitfähriges und stabilisierendes Gerüst für die nicht-leitfähigen Schwefelspezies. Der Einfluss der Nanostruktur des Kohlenstoffs auf die Performance in Schwefel-Kompositelektrodden wurde grundlegend untersucht. Kohlenstoffmaterialien mit verschiedenen spezifischen Oberflächen sowie verschiedenen Porenvolumina wurden von der TU Dresden als Projektpartner synthetisiert und den Partner des Fraunhofer IWS übergeben. Aus der elektrochemischen Charakterisierung ergab sich, dass Durchmesser von Transportporen ≥ 40nm, Oberflächen von über 1000m2/g und hohe Porenvolumina von > 3 cm3g-1 entscheiden sind, um hohe Schwefelbeladungen und gleichzeitig eine hohe Schwefel-Ausnutzung zu erreichen. Für die Überführung der Ergebnisse in die Zellproduktion und die Anwendung in Elektrofahrzeugen sind jedoch weitere F&E-Arbeiten nötig

Nanostructured Si-C Composites As High-Capacity Anode Material For All-Solid-State Lithium-Ion Batteries

Silicon carbon void structures (Si-C) are attractive anode materials for Lithium-ion batteries to cope with the volume changes of silicon during cycling. In this study, Si-C with varying Si contents (28 ‑ 37 %) are evaluated in all-solid-state batteries (ASSBs) for the first time. The carbon matrix enables enhanced performance and lifetime of the Si-C composites compared to bare silicon nanoparticles in half-cells even at high loadings of up to 7.4 mAh cm-2. In full cells with nickel-rich NCM (LiNi0.9Co0.05Mn0.05O2, 210 mAh g-1), kinetic limitations in the anode lead to a lowered voltage plateau compared to NCM half-cells. The solid electrolyte (Li6PS5Cl, 3 mS cm-1) does not penetrate the Si-C void structure resulting in less side reactions and higher initial coulombic efficiency compared to a liquid electrolyte (72.7 % vs. 31.0 %). Investigating the influence of balancing of full cells using 3-electrode ASSB cells revealed a higher delithiation of the cathode as a result of the higher cut-off voltage of the anode at high n/p ratios. During galvanostatic cycling, full cells with either a low or rather high overbalancing of the anode showed the highest capacity retention of up to 87.7 % after 50 cycles. </p

Surface Functionalization of LiNi₇.₀Co₀.₁₅Mn₀.₁₅O₂ with Fumed Li₂ZrO₃ via a Cost-Effective Dry-Coating Process for Enhanced Performance in Solid-State Batteries

Applying a thin film coating is a vital strategy to enhance long term and interface stability of Ni-rich layered oxide cathode materials (NRLOs), especially when they are matched with sulfidic solid electrolytes (SSEs) in solid-state batteries (SSBs). The coating prevents direct contact between the cathode active material (CAM) and the SSE, shielding against parasitic side reactions at the cathode electrolyte interface (CEI). Conventional coatings are based on wet-chemical methods and therefore harmful to the environment and require long-lasting processing and high costs. In this study, we present a versatile, facile and highly-scalable dry-coating method (with suitable equipment up to 500 kg per batch) successfully employed for both multiand single-crystalline LiNi₇.₀Co₀.₁₅Mn₀.₁₅O₂ (NCM70) particles by fumed Li₂ZrO₃ nanostructured particles (LZONPs) via high intensity mixing process. The resulting porous coating layer stays firmly attached at the CAM particle surface without a need of post-calcination step at elevated temperatures. The electrochemical testing results signify enhanced rate capability up to 1.5 mAcm⁻² for both particle types and cyclic stability up to 650 cycles with a capacity retention of 86.1% for singlecrystalline NCM70. We attribute the enhanced performance to the reduced CEI reactions as cathodic charge transfer resistance depressed significantly after dry-coating by LZONPs, being an important step towards sulfidic solid-state batteries