Exploring the Future of Energy Storage on Reddit

On February 21, ACS Publications hosted a Reddit AMA session with ACS Energy Letters Editor-in-Chief Prashant Kamat to discuss peer review, light energy conversion and more. Kamat is the inaugural editor of ACS Energy Letters and is also a principal scientist at the Radiation Laboratory at the University of Notre Dame. His research group focuses on multidisciplinary insight into nanostructure architecture and energy conversion processes, and collaborates with chemists, chemical engineers, and physicists to study the fundamental science and applications of light energy.

ACS Energy Letters launched in July 2016 and is dedicated to showcasing the latest findings in energy conversion and storage from a variety of chemistry disciplines. You can read the first issue here and the first issue of 2017 here.

Professor Kamat’s responses have been lightly edited for clarity.

/u/oolala11: I have 2 parts to my question. What happens when you actually peer review papers?

Also, there are instances of scientists insulting other scientists since their results are different from the known knowledge (say maybe a new discovery), and finding out later on that actually the discovery was major. How can we work to combat this and learn in the 21st century that what is the norm may not actually be right and keep an open mind?

Prashant Kamat: The peer review process maintains the scientific integrity within the publication world. The process of gauging the accuracy of results and validity of the claims by the peers has evolved during last few decades.

The reviewers provide their input to the editors and it is the editors’ decision to weigh in the comments and make a final decision. Since it involves human judgment, it is not fool-proof. The following editorial will provide some insights (Overcoming the Myths of the Review Process and Getting Your Paper Ready for Publication J. Phys. Chem. Lett., 2014, 5 (5) DOI: 10.1021/jz500162r). I have not encountered any case of “insult”, but have seen critical discussion. This is a healthy sign to maintain scientific advance.

Whenever there is a new phenomenon discovered, it is put to rigorous test by the peer reviewers. Usually scientists/reviewers like to critique the observations, analysis, or claims. Often, they demand more explanation. When the authors respond to the reviewers’ concerns the paper becomes scientifically strong.

/u/shiruken: It’s no secret that many of our mobile electronic devices are limited by the capacities of their batteries. Even the promise of solar power is somewhat limited by our ability to store excess energy for use at night. Has battery energy density started to plateau? Are galvanic cells going to be the energy storage device for the foreseeable future or will some other technology supplant it?

Prashant Kamat: For mobile phones and other small-scale applications we need small and light-weight batteries. In some sense we have reached a plateau. Any effort to pack more material to gain higher energy density ends up in disasters. However, we still are in a rising slope in terms of large-scale energy density.

Nearly two-thirds of energy storage is done through 150-year-old lead-acid battery technology. Whether it is a modern-day car or back-up power supply, lead-acid batteries dominate. All electric cars and hybrid cars have shown the potential of Li-ion and other storage batteries for large-scale applications.

Research progress is being made to explore new electrode materials. Redox flow batteries (galvanic cells) are another emerging area that is currently being explored to store energy. It remains to be seen how practical these systems will be in comparison with other storage technologies.

/u/halbornBS: What is your favorite wavelength and why?

Prashant Kamat: My favorite wavelength is 532 nm -green light. Not too high in energy, not too low in energy. Just right (The eyes are more sensitive to green light also).

/u/LateCheckIn: What do you envision as the long term energy solution for the modern world? A hydrogen economy?

Prashant Kamat: Energy derived from hydrogen is clean and one of the highest per mass energy (120.5 kJ/g H2 as opposed to 50.6 kJ/g of methane). It can be cleanly burnt in air or run through fuel cells with water as a byproduct. The problem is the current method of hydrogen generation. It is done using fossil fuels. The best source of hydrogen is water (H2O). We can electrolyze water through PV panels or using photocatalyst assemblies. Imagine a photocatalyst powder that can be spread over a water pond and generate hydrogen by splitting water molecule in sunlight! That’s the Holy Grail in solar fuel generation. Thanks to US Department of Energy for supporting the fundamental research to develop more efficient photocatalyst. Another Holy Grail of hydrogen economy is the storage and transport of hydrogen. Hopefully a hydrogen economy can one day provide us with clean energy.

/u/Chip_N_Charge: Dr. Kamat, thank you for doing this AMA. My question is: from your point of view, considering your extensive knowledge and expertise in the organic-inorganic perovskite solar cells research. What are the current “known” and “unknown” facts about this exciting material? Also, what are the major challenges to implement it commercially, and having it surpass silicon-based solar cells, beside its chemical instability of course?

PS: I’ve actually met you and trained in your labs for few days, couple of years ago. I’d like to say that I thought you were one of the most confident and knowledgeable scientist I’ve ever met in this field. Thank you for the opportunity.

Prashant Kamat: First of all, thank you for your visit and spending time in our laboratory. There are many intriguing aspects of excited state chemistry, especially in mixed halide lead perovskites. Why do they phase segregate in light and recover in dark? How does halide ion mobility influence the solar cell performance? How does surface and intrinsic defects influence the excited state deactivation? Controlling surface chemistry will be another major point of study for future. It is difficult to say where the perovskite solar cell will lead to. Even if we overcome the stability issues, will society accept the lead based system? Given the low price of silicon, can perovskite solar cells compete in the market? Perhaps there is a market for specialized applications such as flexible solar cells.

/u/Chip_N_Charge: Thank you very much for the informative answer.

A follow up regarding the Lead concerns: I’m seeing some research investigating alternative metal centers (like copper) with “some” success, what are your thoughts on these investigations? Wouldn’t a major break-through impact the way our society perceives these materials?

Prashant Kamat: You may want to take a look at this perspective: Toward Lead-Free Perovskite Solar Cells. Feliciano Giustino and Henry J. Snaith ACS Energy Lett., 2016, 1 (6), pp 1233–1240.

/u/Chip_N_Charge: That answers my question perfectly. Thank you and have a wonderful day, sir.


If you have comments or questions for the author of this post, please e-mail: Axial@acs.org.