PITA Fiscal Year 2010 Projects - Environmental Technologies

Physicochemical Transport in Ultra-Thick Battery Electrodes for Large-scale Energy Storage

Principal Investigators: Shawn Lister, Jay Whitacre

Advancements in energy storage technologies are crucial to furthering the integration of renewable electricity generation into the national grid and improving grid reliability. Effective energy storage for renewables must be efficient, reliable, dynamically-matched, environmentally benign, versatile, and cost effective. Although many candidate technologies exist, none yet meet these criteria. A promising technology is the hybrid secondary battery being developed by our industrial partner 44 Tech Inc., which is based on sodium intercalation and electric double layer capacitance electrodes. These potentially transformative batteries use low cost, safe materials, exhibit high durability and reliably sustain charge. However, they require ultra-thick electrodes to meet utility-scale cost targets. Thick electrodes are problematic because of greater transport distances that hinder power and charging/discharging dynamic range.

This interdisciplinary collaboration with industry is aimed at advancing this battery technology with fundamental studies and optimization of transport and electrochemistry in these ultra-thick electrodes. To this end, we will apply advanced diagnostics and computational modeling. Our novel diagnostics use a micro-structured electrode scaffold (MES) to obtain through-plane distribution measurements of electric potential and species concentration through the electrode; a unique capability. The MES provides a structure for intersecting sensing materials with the electrode cross-section at discrete distances through its thickness. Thin electrolyte layers coupled with external reference electrodes allow us to measure electrolyte potential, and potentiometric sensing materials enable measurements of species concentration. In concert with computational modeling, we will use these diagnostics to answer several key questions: 1) how effectively are the thick electrodes utilized, 2) what are the dominant loss mechanisms, and 3) how do alterations in fabrication and materials impact the transport mechanisms and performance? Furthermore, in this project we will use our diagnostics to validate through-plane predictions of porous electrode models for the first time.