PDF Publication Title:
Text from PDF Page: 071
2.5 PRD 5 — Promote Self-healing and Eliminate Detrimental Chemistries to Extend Lifetime and Improve Safety Extending the lifetime and improving the safety of electrical energy storage devices are critical needs for next generation energy storage systems designed for higher energy density and power. Future batteries, for applications such as vehicles or the electricity grid, will require long lifetimes (15-20 years) without significant capacity degradation or catastrophic failure. For many applications, useful battery life is a critical metric: doubling the lifetime effectively cuts the cost in half, a major consideration wherever more cost-effective solutions compete with battery technology. At the same time, catastrophic failure modes (e.g., dendrite shorting) pose critical safety concerns with major liability and market consequences. Successful management of battery design to mitigate degradation, ensure safety, and deliver high performance requires a much deeper understanding of fundamental degradation and failure mechanisms for current and future storage technologies, which can then inform designs that avoid, mitigate, or self- repair these mechanisms. Electrochemical Complexity Drives Degradation and Failure: The complexity of electrochemical devices opens many avenues for degradation and failure. At the cell level, batteries consist of electrodes, electrolytes, and inert components such as current collectors and separators (Figure 2.5.1), arranged such that ions and electrons move across various interfaces in the devices during charging and discharging. Electrodes are typically porous composites or assemblies of micro- or nano-particles containing binders and conductive (usually carbon) additives to provide uninterrupted percolation pathways for both ions and electrons. Alternatively, electrodes may be monolithic structures, particularly polycrystalline thin films, so that complexity is introduced by the presence of grain boundaries and differing orientations of crystallites. Whether composites or monoliths, the electrodes may undergo phase and/or volume changes associated with redox processes during cycling, which can lead to fracture and loss of electrical contact within the electrode and from the current collector. Side reactions with electrolytic solutions or inert components can lead to gas evolution, corrosion, and deleterious changes in interfacial properties. These processes are dependent on the state of charge and cycling conditions and may also occur upon storage (static aging) or rest. Abuse conditions such as a dramatic temperature rise during operation or inadvertent over-charge or over-discharge can, at the least, exacerbate side reactions and mechanical changes in the electrodes and, at worst, lead to catastrophic failure. Controlling the consequences of this complexity in a systematic, rational, and quantitative manner is a grand challenge itself and is fundamental not only in designing electrochemical energy storage devices but also in reducing performance fade and extending lifetime. Degradation Mechanisms: The primary causes of gradual battery degradation and failure are illustrated in Figure 2.5.2.1 They can be grouped into three generic categories, based on losing electrochemical functionality of the working ion (Li+ in the case of Li-ion batteries), the active anode material, and the active cathode material. The loss of working ions in the electrolyte can be caused by side reactions that do not directly store or release energy, such as formation of solid-electrolyte interphases, precipitation from reactions with electrolytes, plating on electrode surfaces instead of intercalating into the electrode interior, or trapping in electrode fragments that have separated from the electrode by fracture. Loss of the activity in the anode or cathode material can result from fracture following repeated volume changes or phase transitions, blocking by surface films, isolation from the working ion by grain boundaries, phase boundaries or other defects, loss of electrical contact to the current collector, or dissolution in the electrolyte.2 NEXT GENERATION ELECTRICAL ENERGY STORAGE PRIORITY RESEARCH DIRECTION – 5 65PDF 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 (Standard Web Page)