Single-Source Alkoxide Precursor Approach to Titanium Molybdate, TiMoO5, and Its Structure, Electrochemical Properties, and Potential as an Anode Material for Alkali Metal Ion Batteries

Transition-metal oxide nanostructured materials are potentially attractive alternatives as anodes for Li ion batteries and as photocatalysts. Combining the structural and thermal stability of titanium oxides with the relatively high oxidation potential and charge capacity of molybdenum(VI) oxides was the motivation for a search for approaches to mixed oxides of these two metals. Challenges in traditional synthetic methods for such materials made development of a soft chemistry single-source precursor pathway our priority. A series of bimetallic Ti-Mo alkoxides were produced by reactions of homometallic species in a 1:1 ratio. Thermal solution reduction with subsequent reoxidation by dry air offered in minor yields Ti2Mo2O4(OMe)(6)((OPr)-Pr-i)(6) (1) by the interaction of Ti((OPr)-Pr-i)(4) with MoO-(OMe)(4) and Ti6Mo6O22((OPr)-Pr-i)(16)(iPrOH)(2) (2) by the reaction of Ti((OPr)-Pr-i)(4) with MoO((OPr)-Pr-i)(4). An attempt to improve the yield of 2 by microhydrolysis, using the addition of stoichiometric amounts of water, resulted in the formation with high yield of a different complex, Mo7Ti7+xO31+x((OPr)-Pr-i)(8+2x) (3). Controlled thermal decomposition of 1-3 in air resulted in their transformation into the phase TiMoO5 (4) with an orthorhombic structure in space group Pnma, as determined by a Rietveld refinement. The electrochemical characteristics of 4 and its chemical transformation on Li insertion were investigated, showing its potential as a promising anode material for Li ion batteries for the first time. A lower charge capacity and lower stability were observed for its application as an anode for a Na ion battery

Avires : simulating tiered memory architectures using dynamic binary instrumentation

Increasingly data-centric workloads have challenged and stressed each component of the modern tiered memory architecture. Active research at different levels of granularity is being conducted to accommodate these now normalized workloads. From a feasibility perspective Dynamic Random-Access Memory (DRAM) and its use in memory is one key point of contention for a data-centric application to scale. Various Non-Volatile Memory (NVM) alternatives have emerged as possible solutions to resolve this bottleneck. Of those, at the time of writing, Intel’s DC Persistent Memory (DCPMM) has emerged as the most marketed and commercially viable alternative. Nonetheless, procuring and working with DCPMM Dual In-line Memory Module (DIMM)s has a significantly high barrier to entry. Consequently, progress made to integrate DCPMM into modern tiered memory architectures and application execution is restricted to niche scientific communities. In order to reduce the barrier to entry, we propose AVIRES — A tiered memory architecture simulator that requires no retrofitting of an application with a simple set up. It uses Intel Pin as its Dynamic Binary Instrumentation (DBI) framework to accurately instrument and interpose different tiered memory configurations onto any application’s execution. We have designed, implemented and evaluated AVIRES’ ability to accurately and efficiently simulate impact on real applications. Furthermore, AVIRES can be instrumented at any granularity the developer deems suitable.Computer Science

A Self-Enforced Optimal Framework for Inter-Platoon Transfer in Connected Vehicles.

Platooning has been identified as a promising strategy towards energy, time management and throughput. In such, a Platoon Leader (PL) provides the Platoon Members (PMs) with autonomous driving service to specific locations. This paper investigates and presents an approach for formulating an architecture to coordinate platoon manipulations while at transit rather than at signalized intersections. The data broadcast by the Vehicles are used to evaluate scores such that a PM can choose a PL and the Platoon analogous to it. Based on this, a multiple-stage platoon formation framework is put forward, which considers the aforementioned nature along with the assessment of an optimal velocity and position for the Incoming Member. It utilizes Vehicle-to-Vehicle communication and a negotiation algorithm based on Dynamic Games of Complete Information towards optimal and fair platoon formation. Simulation results demonstrate that the algorithm significantly reduces the energy consumption along with substantial time gains.</jats:p

How Safe Are Li-Metal Batteries?

For last three decades, Li-ion batteries are the energy storage device of choice; however, the limited theoretical capacity of anodes and cathodes hampers its wide adaption in many applications. Li metal batteries (LMBs) encompassing a lithium metal anodes with sulfur/layered oxide-based cathode material (Li-S and Li-NMC532) provide a sustainable possibility to improve energy/power density. However, thermal safety and overall stability issues continues to hinder its use in practical applications. In spite of the significant effort to alleviate the cycle life of LMBs, the thermal safety aspects of these systems remain unknown, therefore could lead to thermal runaway under extreme conditions. This talk will provide an understanding of the thermal stability of LMBs from materials level to cell level. The amount of exothermic heat generated for Li-NMC (2.9 KJ/g) and Li-S (188 J/g) from the coin cell DSC analysis shows amplified safety risk in Li-NMC532 batteries. </jats:p

Advanced Li Metal Batteries: Thermal Safety Evaluation, Analysis and Mechanistic Elucidation

High theoretical capacity coupled with low operating potential makes Lithium the most promising choice for next-generation batteries. Replacing graphite by Li metal can enhance the energy density three times as compared to conventional Li-ion battery. Lithium is also an essential part of the next generation high energy batteries such as Lithium-Sulphur and Lithium-air batteries. However, the high reactivity of Li metal with electrolyte leads to dendritic growth, poor cycle life and safety hazards in Li metal batteries. Till date, there has been no study on the thermal characteristics of Li metal batteries. The thermal characteristics of Li metal batteries using advanced multiple-mode calorimetry (MMC) for the coin cell format under fully charged and discharged conditions is studied. In the conventional differential scanning calorimetry (DSC) ex-situ studies of a component or two from the battery, possibly could lead to some artifacts. Therefore, MMC is utilized to directly study the thermal behavior of whole coin cell comprising anode, cathode, electrolyte, and separator with thermally stable leak proof gasket till 300 oC. Thermal runaway of two types of Li metal batteries with different chemistries namely Li-Sulfur and Li-NMC are measured and compared. The MMC of Li-S battery coin cell in fully charged conditions showed a sharp exothermic peak positioned at 180 °C originating from the reaction between the Li metal and sulfur in presence of the electrolyte. Though Li-S batteries are assumed to be safer, an exothermic reaction between Li and S cathode leads to thermal runaway once the Li metal melts. The MMC of Li-NMC cell in the coin cell format also exhibits endothermic and exothermic peaks arising from the melting of Li and reaction of Li with electrolyte/cathode. This exothermic reaction leads to thermal runaway in Li-NMC around 180°C. The detailed endothermic and exothermic heat generation values in J/g, peak temperature, its source based on interfacial reactions and mechanistic elucidation will be discussed. </jats:p