Lithium-Ion Batteries: Applications for Renewable Power Grids

Grant Tipton gctipton@umd.edu Science and Global Change

Atmospheric and Oceanic Sciences May, 2016

Why Batteries?

Conclusions Results

Lithium-Ion Batteries

Acknowledgments to Dr. David Eubanks, Dr. Thomas Holtz, Dr. John Merck, and John Smirnow

Our current society is addicted to power. Not the abstract sense of power, but literal electrical power. Conventional means for generating this power have been shown to be very damaging to the planet, and there is a large movement towards renewable sources. Unfortunately these renewable sources are not directly controllable, and require batteries to stabilize power flow. For example a solar system requires batteries to store power for the night. These batteries are going to be an essential part of our updated power grids, and it is important for policy makers to be well informed of their options. According to the US Department of Energy, power grid storage has 4 major challenges. These are,

1. Cost Effectiveness 2. Safety and Reliability 3. An Equitable Regulatory

Environment 4. Industry Acceptance

I have investigated several types of batteries for these qualities, and have used my findings to make an informed decision.

Lithium-ion Batteries (LIB’s) are widely accepted as superior to conventional battery technologies, and as such are the focus of this project. An LIB has 3 general parts, the negative terminal (anode) which is most commonly graphite, the organic electrolyte through which lithium ions flow, and the positive terminal (cathode) which is some metal oxide. The cathode currently has the largest variety in viable materials and makeups, and for this reason I focused on only changing the cathode. There were three cathode variants I examined, lithium iron phosphate (LFP), lithium cobalt oxide (LCO) and lithium nickel manganese cobalt oxide composite (LCO-NMC).

Through my research, I have determined that LFP batteries are best suited to use in power grids. Compared to the other batteries examined they perform better in each DOE challenge category.

The scope of this project was rather limited, however the question posed has a rather definitive answer. There has been enough data published on these varieties of LIB’s to make a fairly confident statement that LFP’s are superior to LCO’s and LCO-NMC’s. With that being said the one category I would like to further investigate is the safety of these various batteries. Unfortunately I was unable to find quantitative data on safety or stability. While almost all sources agree that LFP’s are safer than the conventional alternatives, I could not find a satisfactory explanation for that. I would suggest that the most important direction of continued research on these battery technologies is to quantify the safety. Another important side of research that was beyond my capabilities, is developing new battery technologies. Currently it appears LFP batteries are the best available, but some new system could very easily surpass them. There are many exciting paths being explored in the field of LIB’s, but all of them are outside the scope of this project.

My methods for this project focused on collecting quantitative data on LIB’s to enable an unbiased comparison. For certain facets of the batteries this was quite simple. There is quite a bit of data published in journals such as Energy on battery lifespans and charge density. The one challenge with this data was synthesizing several articles. Most publications I found only dealt with one aspect of one type of battery. The other aspects of batteries I examined were more difficult to find quantitative data on. Most researchers did not focus on the cost or safety of their specific technologies. The most useful source of information I was able to find on these areas were reports by the US Department of Energy. Reports by the DOE and the few other sources I could find, although they did not give me quantitative data, did answer enough of my questions for me to feel reasonably confident in my results.

Methods

Which type of Lithium-Ion Battery is best for renewable power grid stabilization?

Adapted from “A comparison of lead-acid and lithium-based battery behavior and capacity fade in off-grid renewable charging applications”

ViPer Group, Purdue University. Li_1.jpg [Technical figure of a lithium ion battery]. Retrieved from https://engineering.purdue.edu/ViPER/research.html

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LFP LCO-NMC LCO

Cost by Charge ($/Ah)

Adapted from “Modeling the Performance and Cost of Lithium-Ion Batteries for Electric-Drive Vehicles”, “An Advanced Lithium-Ion Battery Based on a GrapheneAnode and a Lithium Iron Phosphate Cathode”, “Synthesis and high rate properties of nanoparticled lithium cobalt oxides as the cathode material for lithium-ion battery”, and “Development and challenges of LiFePO4 cathode material for lithium-ion batteries”

Cobalt batteries are described as “unsafe and environmentally toxic”. While LFP’s are described as thermally stable and environmentally benign

Yuan, L., Wang, Z., Zhang, W., Hu, X., Chen, J., & Goodenough, J. B. (2011). Development and challenges of LiFePO4 cathode material for lithium-ion batteries. Energy & Environmental Science 0

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LFPLCOLCO-NMCLead Acid

The chart to the left shows the cost of each battery by charge capacity, and illustrates the affordability of LFP’s. The graph above demonstrates the superior lifespans of LIB’s and LFP’s in particular.

Gyuk, I., Johnson, M., Vetrano, J., Lynn, K., Parks, W., Handa, R., . . . Braccio, R. (2013, December). (USA, Department of Energy). Retrieved from http://www.sandia.gov/ess/docs/other/Grid_Energy_Storage_Dec_2013.pdf