PDF Publication Title:
Text from PDF Page: 046
REPORT OF THE BASIC RESEARCH NEEDS WORKSHOP Structuring of Ions at Interfaces and Electrical Double Layer: While interfacial fluid structure and transport of aqueous-based electrolytes at low (micromolar) and moderate (millimolar to molar) salt concentrations are mature areas of inquiry, the analogous features for aqueous electrolytes containing very high concentrations (e.g., 10-20 M) of dissolved salts and for non-aqueous electrolytes, including room-temperature ionic liquids and hybrid electrolytes containing nanoparticulate additives, are poorly understood. An emerging theme from recent experiments is that these materials exhibit complex structure and unusual interfacial transport behavior with a rich variety of features on different length scales. This includes the presence of dislocation-type defects in liquid crystal-like arrangement of ions at solid interfaces, lateral ordering on the electrode surface on the molecular scale, and the presence of large-scale structural domains composed of particles or molecules as seen in Figure 2.3.3. There is evidence that the presence of such structures at a liquid electrolyte/solid interface can increase the electrochemical stability of the liquid by more than 1 V.12 The evolution of these interfaces under a bias voltage has not been explored, and the effect on ionic transport across the structured electrical double layer (EDL) is entirely unknown. Similar experimental observations with high lateral resolution for organic electrolytes are entirely missing. However, molecular dynamics simulations13 and neutron scattering experiments14 suggest rich interfacial physical phenomena in such systems. Further, the structural details of the EDL are not captured by theoretical simulations, despite their importance to explain unusual charging dynamics, as observed with scattering techniques,15,16 and the enhanced electrochemical stability of aqueous electrolyte with high salt concentration.5 Likewise, understanding is lacking of the EDL structures across multiple length scales involving local surface charges and chemistry, their evolution with bias, and their correlation to energy storage properties. Of special interest is the role played by field-induced structuring of ions in electrolytes on interphase formation processes and morphology. A potential added benefit for understanding the EDL in confined spaces is that such knowledge will allow a deeper understanding of the processes by which multivalent ions are transported in electrochemical membranes and at electrodes. Electrode/Solid-Electrolyte Interfaces: Replacing liquid electrolytes with solid electrolytes could revolutionize battery technology. Long-standing challenges related to poor room-temperature ionic conductivity of solid- state electrolytes, higher overhead costs associated with high temperature operation of electrochemical cells, and environmental sensitivity of promising solid electrolytes have limited progress in this area. While there have been recent advances in solid ion conductors exhibiting conductivities comparable to liquid electrolytes, little is known about their integration with solid electrodes and into solid-state batteries. What are the design rules? How are solid-solid interfaces formed? How does charge transport and charge transfer occur at these interfaces? What mechanical stresses arise during fabrication and during cycling? How does the material respond to these stresses and influence reaction rates at the electrodes? These are examples of aspects that must be considered to realize the potential of all-solid-state batteries. These questions relate to solid electrolyte interfaces at the anode and cathode. Phase or grain boundaries within the solid electrolyte or the electrodes provide additional interfaces, which may evolve during cycling as changes in crystal phases or grain boundaries or the formation of a crystalline/amorphous interface. Research on these interfaces is needed to understand, quantify, and control reaction kinetics during metal plating both at the current collector and within a solid electrolyte due to defects. To date, there is a good predictive foundation for reactions at a crystalline interface, but these models break down with glasses and meta-stable materials that can cycle thousands of times with Li anodes in micro-batteries.17 Among all solid-state electrochemical cells, batteries based on Li, Na, and Si anodes are considered most promising because they enable battery designs that offer large improvements in specific energies on a volume or mass basis. Solid-state thin film batteries provide a mechanism to prepare materials with well-defined and stable interfaces. Recent work on a 5-V solid-state battery (Li/LiMn1.5Ni0.5O4) revealed that, with the formation of the right interface structure, these batteries can operate for over 10,000 cycles with greater than 90% capacity retention (Figure 2.3.4).17 This result demonstrates that it is possible to cycle Li metal and an advanced high- energy cathode. Detailed knowledge of the interfaces between the Li metal, a lithium phosphorus oxynitride (LiPON) solid electrolyte, and LiMn1.5Ni0.5O4 cathode will provide a pathway to prepare suitable interfaces on new solid electrolytes that may be compatible with Li metal and other cathode chemistries. This understanding could be leveraged to direct the formation of suitable bonding motifs and configurations to enable low impedance interfaces. If further developed, these techniques could also be utilized to understand the structure and morphology for the solid-liquid interface in non-aqueous as well as aqueous electrolytes. 40 PRIORITY RESEARCH DIRECTION – 3PDF Image | Next Generation Electrical Energy Storage
PDF Search Title:
Next Generation Electrical Energy StorageOriginal File Name Searched:
BRN-NGEES_rpt-low-res.pdfDIY PDF Search: Google It | Yahoo | Bing
Sulfur Deposition on Carbon Nanofibers using Supercritical CO2 Sulfur Deposition on Carbon Nanofibers using Supercritical CO2. Gamma sulfur also known as mother of pearl sulfur and nacreous sulfur... More Info
CO2 Organic Rankine Cycle Experimenter Platform The supercritical CO2 phase change system is both a heat pump and organic rankine cycle which can be used for those purposes and as a supercritical extractor for advanced subcritical and supercritical extraction technology. Uses include producing nanoparticles, precious metal CO2 extraction, lithium battery recycling, and other applications... More Info
| CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com | RSS | AMP |