Battery Power - Spring 2015 - (Page 30)

Research & Development Compact Batteries Enhanced by Spontaneous Silver Matrix Formations In a promising lithium-based battery, the formation of a highly conductive silver matrix transforms a material otherwise plagued by low conductivity. To optimize these multi-metallic batteries, and enhance the flow of electricity, scientists needed a way to see where, when and how these silver, nanoscale "bridges" emerge. Now, researchers from the US Department of Energy's Brookhaven National Laboratory and Stony Brook University have used x-rays to map this changing atomic architecture and revealed its link to the battery's rate of discharge. The study shows that a slow discharge rate early in the battery's life creates a more uniform and expansive conductive network, suggesting new design approaches and optimization techniques. "Armed with this insight into battery cathode discharge processes, we can target new materials designed to address critical battery issues associated with power and efficiency," said study coauthor Esther Takeuchi, a SUNY Distinguished professor at Stony Brook University and chief scientist in Brookhaven Lab's Basic Energy Sciences Directorate. The scientists used bright x-ray beams at Brookhaven Lab's National Synchrotron Light Source (NSLS), a DOE Office of Science User Facility, to probe lithium batteries with silver vanadium diphosphate (Ag2VP2O8) electrodes. This promising cathode material, which may be useful in implantable medical devices, exhibits the high stability, high voltage and spontaneous matrix formation central to the research. "The experimental work, in particular the in-situ x-ray diffraction in batteries totally encased in stainless steel, should prove useful for industry as it can penetrate prototype and production-level batteries to track their structural evolution during operation," Takeuchi said. Into the Matrix As these single-use batteries discharge, the lithium ions stored in the anode travel to the cathode, displacing silver ions along the way. The displaced silver then combines with free electrons and unused cathode material to form the conductive silver metal matrix, acting as a conduit for the otherwise impeded electron flow. "To visualize the cathode processes within the battery and watch the silver network take shape, we needed a very precise system with high-intensity xrays capable of penetrating a steel battery casing," said study coauthor and Stony Brook University Research Associate professor Amy Marschilok. "So we turned to NSLS." Energy dispersive x-ray diffraction (EDXRD) at NSLS provided this real-time, in situ, visualization data. In EDXRD, intense beams of x-rays passed through the sample, losing energy as the battery structure bent the beams. Each set of detected beam angles, like time-lapse images, revealed the shifting chemistry as a function of battery discharge. Optical images of the non-discharged cathode, showing key differences in the lithium-facing and steel-facing sides. 30 Battery Power * Spring 2015

Table of Contents for the Digital Edition of Battery Power - Spring 2015

Battery Power - Spring 2015
Batteries: An Integrated Solution
Preventing Counterfeiting: Challenges and Selection Criteria for An Ideal Authentication Solution
Extending Battery Life
Batter Management with an Intelligent Battery Sensor is Vital to The Success of Future Automotive Designs
ICs & Semiconductors
Testing & Monitoring
Conference Preview: Critical Power 2015
Research & Development
Industry News
Application Profile
Calendar of Events

Battery Power - Spring 2015