Status, Opportunities, and Challenges of Electrochemical Energy Storage

INTRODUCTION Today’s electricity generation and transportation depend heavily on fossil fuels. As such, electricity generation and transportation have become two major sources of CO2 emissions leading to global warming. The concerns over environmental pollution and finite fossil fuel resources have spurred great interest in generating cleaner electricity from renewable energy sources such as solar, ocean/lake wave, and wind, and in developing electric vehicles (EV). However, the renewable energy sources and energy/power demands by industries and transportation are not constant. For example, sunlight and wind vary from time-totime and from location-to-location, and energy/power demands change from peak time to off-peak time for industries and from accelerating-to-braking for EVs. In order to harvest the renewable energies effectively and for widespread electrification of transportation, electrochemical energy storage (EES) is necessary to smooth the intermittency of renewable electricity generation and reduce or eliminate the CO2 emissions from traditional transportation. The EESs are an indispensable component for future smart grids that integrate significant amounts of renewable energy resources and provide electricity to electrical vehicles. In this article, the status, opportunities, and challenges will be discussed for the future research and development of EESs.