624 Ingenieurbau und Umwelttechnik
Refine
Document Type
Language
- English (6)
Has Fulltext
- yes (6)
Is part of the Bibliography
- yes (6)
Keywords
- Lithium-ion storage (1)
- MXene (1)
- NMR spectroscopy (1)
- aqueous electrolytes (1)
- battery production (1)
- battery research (1)
- carboxylation (1)
- cell production (1)
- data structures (1)
- desalination (1)
Scientific Unit
- Energy Materials (6)
- Structure Formation (1)
Microporous carbonaceous electrode materials store charge by ion electrosorption onto the electrode surface. Despite significant efforts to understand this phenomenon, a definitive picture of the adsorption mechanisms within these complex nanoscale structures is lacking. Here, we use nuclear magnetic resonance (NMR) spectroscopy to directly observe and quantify aqueous adsorbate partitioning behavior driven by spontaneous physisorption within the micropores. Our results show that the solvation properties of the electrolyte ions influence the ionophilicity/ionophobicity of the adsorbate-carbon system, with ionophilic and ionophobic systems exhibiting distinct behavior concerning the electrolyte loading volume. Micropore diameter is also shown to influence spontaneous electrolyte partitioning behavior and disturb ion solvation. In situ NMR spectroscopy using a working supercapacitor comprising microporous carbon electrodes with aqueous sodium sulfate and aqueous sodium bis(trifluoromethane)sulfonimide electrolytes indicates that spontaneous electrolyte partitioning behavior influences the charge-balancing mechanism. Our results suggest that spontaneously ionophilic systems favor charge-balancing by counter-ion adsorption under an applied voltage, and spontaneously ionophobic systems favor a co-ion ejection mechanism under an applied potential. These results provide new molecular-level insight into the role of electrolyte properties on spontaneous physisorption behavior and charged electrosorption behavior within microporous carbon electrodes.
MXene is investigated as an electrode material for different energy storage systems due to layered structures and metal-like electrical conductivity. Experimental results show MXenes possess excellent cycling performance as anode materials, especially at large current densities. However, the reversible capacity is relatively low, which is a significant barrier to meeting the demands of industrial applications. This work synthesizes N-doped graphene-like carbon (NGC) intercalated Ti3C2Tx (NGC-Ti3C2Tx) van der Waals heterostructure by an in situ method. The as-prepared NGC-Ti3C2Tx van der Waals heterostructure is employed as sodium-ion and lithium-ion battery electrodes. For sodium-ion batteries, a reversible specific capacity of 305 mAh g−1 is achieved at a specific current of 20 mA g−1, 2.3 times higher than that of Ti3C2Tx. For lithium-ion batteries, a reversible capacity of 400 mAh g−1 at a specific current of 20 mA g−1 is 1.5 times higher than that of Ti3C2Tx. Both sodium-ion and lithium-ion batteries made from NGC-Ti3C2Tx shows high cycling stability. The theoretical calculations also verify the remarkable improvement in battery capacity within the NGC-Ti3C2O2 system, attributed to the additional adsorption of working ions at the edge states of NGC. This work offers an innovative way to synthesize a new van der Waals heterostructure and provides a new route to improve the electrochemical performance significantly.
An ontology for the structured storage, retrieval, and analysis of data on lithium-ion battery materials and electrode-to-cell production is presented. It provides a logical structure that is mapped onto a digital architecture and used to visualize, correlate, and make predictions in battery production, research, and development. Materials and processes are specified using a predetermined terminology; a chain of unit processes (steps) connects raw materials and products (items) of battery cell production. The ontology enables the attachment of analytical methods (characterization methods) to items. Workshops and interviews with experts in battery materials and production processes are conducted to ensure that the structure is conformable both for industrial-scale and laboratory-scale data generation and implementation. Raw materials and intermediate products are identified and defined for all steps to the final battery cell. Steps and items are defined based on current standard materials and process chains using terms that are in common use. Alternative structures and the connection of the ontology to other existing ontologies are discussed. The contribution provides a pragmatic, accessible way to unify the storage of materials-oriented lithium-ion battery production data. It aids the linkage of such data with domain knowledge and the automation of data analysis in production and research.
Owing to an expanding economy and growing population, there is increasing consumer demand for freshwater. However, with global climate change and water pollution issues, there is rising water stress in many countries worldwide. Electrochemical water desalination technologies such as capacitive deionization (CDI) utilize electrical energy to store ions in porous materials and provide energy-efficient water desalination. However, due to the cation and anion exchange process during the charging and discharging processes, CDI is considered suitable for low salinity water desalination (salinity of 1-10 g/L). This dissertation explores novel approaches to next-generation CDI for better desalination performances and water desalination at high ionic strength. In particular, the ability of sub-nanometer carbon pores (ultramicropores) to enable highly efficient CDI even at seawater salinity is demonstrated based on unexpected simulation predictions. This unique ability originates from the energy barrier of ion solvation for pores smaller than the solvation shell. Consequently, uncharged carbon ultramicropores behave ionophobic and overcome the limitation of CDI only to be suitable for remediation of brackish water. Ultramicropores also provide novel perspectives for ion separation via the interplay of intrinsic and kinetic ion selectivity. This work also establishes electrocatalytic fuel cell desalination, whereby conventional fuel cell technology can easily be adapted to generate electricity, heat, and desalinated water concurrently.
Energy-efficient technologies for the remediation of water and generation of drinking water is a key towards sustainable technologies. Electrochemical desalination technologies are promising alternatives towards established methods, such as reverse osmosis or nanofiltration. In the last few years, hydrogen-driven electrochemical water purification has emerged. This review article explores the concept of desalination fuel cells and capacitive-Faradaic fuel cells for ion separation.
Environmentally sustainable, low-cost, flexible, and lightweight energy storage technologies require advancement in materials design in order to obtain more efficient organic metal-ion batteries. Synthetically tailored organic molecules, which react reversibly with lithium, may address the need for cost-effective and eco-friendly anodes used for organic/lithium battery technologies. Among them, carboxylic group-bearing molecules act as high-energy content anodes. Although organic molecules offer rich chemistry, allowing a high content of carboxyl groups to be installed on aromatic rings, they suffer from low conductivity and leakage to the electrolytes, which restricts their actual capacity, the charging/discharging rate, and eventually their application potential. Here, a densely carboxylated but conducting graphene derivative (graphene acid (GA)) is designed to circumvent these critical limitations, enabling effective operation without compromising the mechanical or chemical stability of the electrode. Experiments including operando Raman measurements and theoretical calculations reveal the excellent charge transport, redox activity, and lithium intercalation properties of the GA anode at the single-layer level, outperforming all reported organic anodes, including commercial monolayer graphene and graphene nanoplatelets. The practical capacity and rate capability of 800 mAh g−1 at 0.05 A g−1 and 174 mAh g−1 at 2.0 A g−1 demonstrate the true potential of GA anodes in advanced lithium-ion batteries.
