California Institute Of Technology Research Articles

Irving Langmuir Award in Chemical Physics: George W. Flynn

Sponsor: ACS and the ACS Division of Physical Chemistry Citation: For contributions to our fundamental understanding of the structural and chemical behavior of graphene interfaces. Current position: Eugene Higgins Professor of Chemistry, Columbia University Education: B.S., chemistry, Yale University; Ph.D., chemistry, Harvard University Flynn on his scientific role model and why: “Four mentors have had a significant influence in determining the course of my scientific career: my high school chemistry teacher, Mr. Coburn, who made chemistry a remarkably clear discipline and introduced me to independent research; Ali Javan, who taught me to think like a physicist about the interaction of light and matter; and John Baldeschwieler and E. Bright Wilson, who were my Ph.D. mentors and taught me the importance of clear thinking in scientific discussions and about being fearless in attacking new research areas.” What his colleagues say: “In groundbreaking work, he demonstrated that single sheet graphenes are much more reactive than multiple sheet materials. His fundamental work will surely be of great help to investigators who are working on electronic devices based on graphene and doped-graphene materials.”—Harry B. Gray, California Institute of Technology.

Herbert C. Brown Award for Creative Research in Synthetic Methods: Gregory C. Fu

Sponsor: Purdue Borane Research Fund and the Herbert C. Brown Award Endowment Citation: For the development of nickel- and copper-catalyzed cross-coupling methods and of nucleophile-catalyzed enantioselective reactions. Current position: Norman Chandler Professor of Chemistry & Chemical Engineering, California Institute of Technology Education: B.S., chemistry, Massachusetts Institute of Technology; Ph.D., chemistry, Harvard University Fu on what he hopes to accomplish in the next decade: “During the next decade, we hope to provide general solutions to coupling a wide range of nucleophiles and alkyl electrophiles, including enantioconvergent processes. We believe that success in this area could be transformative for organic synthesis.” What his colleagues say: “Fu has made several pathfinding contributions to the development of synthetic methods that have impacted the way that chemists think about building organic molecules.”—Peter Dervan, California Institute of Technology.

ACS Award for Creative Work in Synthetic Organic Chemistry: Brian M. Stoltz

Sponsor: MilliporeSigma Citation: For the development of efficient methods, particularly cascade reactions, that allow for the efficient synthesis of complex organic molecules. Current position: professor of chemistry, California Institute of Technology Education: B.S., chemistry, Indiana University of Pennsylvania; B.A., German, Indiana University of Pennsylvania; M.S., organic chemistry, Yale University; Ph.D., organic chemistry, Yale University Stoltz on what gets his creative juices flowing: “Creativity is the beauty that underscores the science. I’ve been incredibly lucky to have had a number of critically important mentors throughout the course of my scientific development. Additionally, I have benefited from exceedingly talented and quite brilliant students and colleagues in my 17 years at Caltech. It is the collective of these individuals that inspires and pushes me to a higher level.” What his colleagues say: “He is well recognized as one of the young leaders in organic synthesis and is one of the few who not only develop both new catalytic methodology but also demonstrate the methods in complex total synthesis.”—Robert H. Grubbs, California Institute of Technology.

Modelling gene regulation: (De)compositional and template-based strategies

Although the interdisciplinary nature of contemporary biological sciences has been addressed by philosophers, historians, and sociologists of science, the different ways in which engineering concepts and methods have been applied in biology have been somewhat neglected. We examine – using the mechanistic philosophy of science as an analytic springboard – the transfer of network methods from engineering to biology through the cases of two biology laboratories operating at the California Institute of Technology. The two laboratories study gene regulatory networks, but in remarkably different ways. The research strategy of the Davidson lab fits squarely into the traditional mechanist philosophy in its aim to decompose and reconstruct, in detail, gene regulatory networks of a chosen model organism. In contrast, the Elowitz lab constructs minimal models that do not attempt to represent any particular naturally evolved genetic circuits. Instead, it studies the principles of gene regulation through a template-based approach that is applicable to any kinds of networks, whether biological or not. We call for the mechanists to consider whether the latter approach can be accommodated by the mechanistic approach, and what kinds of modifications it would imply for the mechanistic paradigm of explanation, if it were to address modelling more generally.

Immortality, and: The Visitation, and: Casanova: A Translation from Fellini

Immortality, and: The Visitation, and: Casanova: A Translation from Fellini Yun Wang (bio) Immortality My father washed his only shirt at nightdried it by the fire in a haunted houseby a white river in the mountainsHe pours osmanthus black teainto blue porcelain cups in my dreamsfive years after his death My mother gazed at Venus at dawnas she cleaned chamber potsfor wealthy classmatesShe bought me the diamond ringthat she had wanted all her lifea few months before she died I watch peonies of white cloudsbloom in the Maya blue skycontemplate the filaments of galaxiesand the voids they frameThe Universe expandsMy son promises to build me a spaceship The Visitation The doctor said it was nerve disorderthat caused noises in the earsSchumann listened and went mad [End Page 91] The voices chose him because of his musicA thousand fairies dancing in shoes of flame It created a riot in their worldThey wanted him to stop They came through the piano'sblack and white doorsThey stitched his mind into a maze Casanova: A Translation from Fellini Famous for private entertainment and winning public competitions of copulation, he received an invitation from an anonymous dignitary. He rode for miles in the gondola to perform. After saluting, he swirled, the curious nun on his waist, his scarlet cape a flag pulling eyes behind carved peeping holes. When the show ended, he asked for permission to present his essays and inventions. His voice echoed in the deserted monastery. ________ Her Royal Highness in disguise put a slender finger on his lips. She played the cello in a string quartet, in the marble court lit by crystal chandeliers. The deep calm of the cello overcame him. He fled into the rose garden, tears streaming. He planned a future with her. She departed in a gilded carriage while he slept. ________ Old and gray, he begged for food. The same waltz haunted his dreams each night. A procession of red hooded priests. Then the princess stepped out of a golden carriage. Breaking into the shop where she was displayed, he once made love to her in despair. She jerked her painted head, reached out a porcelain hand. He held it. They danced. [End Page 92] Yun Wang Yun Wang is the author of poetry books The Book of Totality (Salmon Poetry Press) and The Book of Jade (Winner of the 15th Nicholas Roerich Poetry Prize, Story Line Press); the poetry chapbooks Horse by the Mountain Stream (Word Palace Press) and The Carp (Bull Thistle Press); and a book of poetry translations, Dreaming of Fallen Blossoms: Tune Poems of Su Dong-Po (White Pine Press, forthcoming). Her poems have been published in numerous literary journals including the Kenyon Review, Cimarron Review, Salamander Magazine, Green Mountains Review, and International Quarterly. She is a cosmologist at California Institute of Technology. Copyright © 2018 University of Nebraska Press

Multiple sclerosis: what's it got to do with your guts?

Multiple sclerosis: what's it got to do with your guts?

Parting ways with ABET

ABET, formerly the Accreditation Board for Engineering & Technology, has been evaluating and endorsing chemical engineering programs at universities in the U.S. since the 1930s. California Institute of Technology was one of the first to have its program accredited by ABET in October 1936. Despite that long history, Caltech’s chemical engineering department has now decided that neither it nor its students benefit from the ABET stamp of approval. The department decided last year and publicly announced this fall that it would no longer pursue accreditation and published an open letter on its website. And Caltech isn’t alone. At their annual retreat in September, the chemical engineering faculty at Stanford University voted to withdraw from the ABET process as well. More universities may follow suit. Seven engineering societies, including the American Institute of Chemical Engineers, or AIChE, originally founded ABET to establish criteria for the professional development of engineers and to

The invisible hand

There's something odd going on in the solar system. People once settled and peaceful home is looking increasingly disturbed and deranged. Bits of it are flying about in eccentric and inexplicable ways. Other bits seemingly shouldn't be there at all. Meanwhile, the sun is rotating at a rakish angle they are hard-pressed to explain. Mike Brown, a planetary scientist at the California Institute of Technology in Pasadena, thinks he can explain these strange goings on. There is an unsettling influence in the room: something big and distinctly mobile. Not a poltergeist--but another planet. Here, Lovett investigates a theory of a bizarre hidden planet manipulating the solar system.

Quantum origins of space-time

Chunjun Cao and Sean Carroll at the California Institute of Technology in Pasadena have tried to extract the kind of space-time we would find in the vicinity of our solar system from standard quantum mechanics. This type of space-time is one whose curvature is mostly flat, but with small undulations due to weak gravitational fields. To see if space-time can emerge from this quantum description, Cao and Carroll used an abstract mathematical concept called Hilbert space that can be split into different tiny parts, such that each one corresponds to a single point in 3D space. The researchers relate entanglement to geometry by further assuming that the greater the entanglement between two parts, the closer they are. The entire system is also assumed to be in some state of equilibrium, such that increasing the entanglement in one region decreases it elsewhere, and vice versa. Given a handful of such assumptions, Cao and Carroll have shown that the equations governing the dynamics of entanglement are similar to Einstein's equations of general relativity. In other words, space-time and gravity emerge from entanglement.

Trio surfs gravitational waves to Nobel glory.

Testy debate over who should win defused by potential laureate's death.

Combinatorial Magnetron Sputtering

SummaryCombinatorial Magnetron Sputtering is a process where large numbers of chemically distinct thin film samples can be made in a single deposition. Utilizing a multiple cathode sputter system manufactured by the Kurt J. Lesker Company, researchers at the California Institute of Technology have developed a process which enables them to make 5,000 unique compositions on one 4″ wafer in one deposition. Compositional control is achieved by varying the tilt angle of the cathodes and Z‐distance relative to the substrate. In addition to this extraordinary fabrication capability, the group also developed a model which can predict the range of future compositions as well as a rapid characterization technique which can sort through thousands of compositions in a 24 hour period.

Inertial Forces from Earthquakes on a Hyperloop Pod

Brief Report| September 25, 2017 Inertial Forces from Earthquakes on a Hyperloop Pod Thomas H. Heaton Thomas H. Heaton aDepartment of Mechanical and Civil Engineering, California Institute of Technology, MC 104‐44, Pasadena, California 91125, heaton@caltech.edu Search for other works by this author on: GSW Google Scholar Author and Article Information Thomas H. Heaton aDepartment of Mechanical and Civil Engineering, California Institute of Technology, MC 104‐44, Pasadena, California 91125, heaton@caltech.edu Publisher: Seismological Society of America First Online: 27 Sep 2017 Online Issn: 1943-3573 Print Issn: 0037-1106 Bulletin of the Seismological Society of America (2017) 107 (5): 2521–2524. https://doi.org/10.1785/0120170054 Article history First Online: 27 Sep 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Thomas H. Heaton; Inertial Forces from Earthquakes on a Hyperloop Pod. Bulletin of the Seismological Society of America 2017;; 107 (5): 2521–2524. doi: https://doi.org/10.1785/0120170054 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyBulletin of the Seismological Society of America Search Advanced Search Abstract High‐speed transit (⁠1300 km/hr⁠) using pods traveling in evacuated tubes has been proposed. This Short Note addresses how earthquake ground shaking is changed when it is experienced by a high‐speed pod that is confined to a track. In particular, earthquake motions can cause lateral deformations of the tube that cause centripetal forces in the pod. I discuss the nature of these forces for the cases of (1) a tube that crosses a fault offset, (2) a tube that is deformed by traveling waves in the Earth, and (3) a tube that resonates between fixed points (e.g., a simple bridge). I suggest several schemes to control the peak centripetal accelerations of the pod. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

@Caltech: Art, Science and Technology, 1969–1971

In 1969, the vision of a handful of professors at California Institute of Technology resulted in an initiative to bring artists and scientists together to “see what happens.” The experiment embodied insurgent notions of that era—ideas that would once again become manifest a generation later in the young 21st century’s art-science fusion. Out of this venture came hints of new visual vocabularies and ways of making, as well as an awareness of fault lines between the two cultures. To one young student who found his way into it, the Caltech experience became a transforming moment.

Early-career researchers: an interview with Kakani Katija.

Kakani Katija is a Principal Engineer at the Monterey Bay Aquarium Research Institute, USA, where she designs and builds instrumentation to study marine invertebrate ecomechanics. She received her Bachelor's degree in Aeronautics and Astronautics from the University of Washington, USA, before moving to the California Institute of Technology, USA, for her Master's degree in Aeronautics with Morteza Gharib and PhD in Bioengineering in the laboratory of John Dabiri, completed in 2010. Katija was recognised as a National Geographic Emerging Explorer in 2011 and has given presentations at TEDYouth and TEDWomen.

High Energy Density Lithium/Sulfur Batteries for NASA and DoD Applications

High Energy Density Lithium/Sulfur Batteries for NASA and DoD Applications Ratnakumar Bugga*, Simon Jones, John-Paul Jones, Jasmina Pasalic, Frederick C. Krause, Mary Hendrickson** and Edward Plichta** Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 **US Army RDECOM CERDEC, 5100 Magazine Rd., Aberdeen Proving Ground, MD 21005 * rvbugga@jpl.nasa.gov Li-ion batteries, being compact, lightweight, and durable, have contributed to a significant enhancement or even enablement of several planetary and space missions. However, NASA’s future missions, e.g., Astronaut’s Portable Life Support System (PLSS) for Extra-Vehicular Activities (EVA), small planetary rovers, planetary probes, CubeSats etc., require battery technologies with higher specific energies and energy densities, for short cyclic lifetimes. Similarly, DoD is interested in the development of a high energy rechargeable battery system for soldier applications. The lithium/sulfur system is deemed the most viable future technology, because of its high theoretical specific energy (3-4x vs Li-ion). Despite several years of development, this system hasn’t matured yet, mainly due to the challenges from the soluble polysulfides, which results in a ‘redox shuttle’ and a deposition of lihium sulfides and impedance growth at the lithium anode. Several attempts were reported in the literature with novel cathode designs, e.g., hierarchical porous carbon structures to sequester sulfur and its reduction products, and also with electrolyte solutions to minimize their solubility. 1-3 Good cycle life was achieved in some of these cases with nanostructured sulfur cathodes in both organic electrolytes containing suitable additives (LiNO3) and in ionic liquids, but the sulfur loadings in the cathodes are much lower (below 4 mg/cm2) than desired. For example, to realize high specific energy from a Li/S cell, sulfur loading will need to be high, i.e., > 12 mg/cm2 per side or >6 mAh/cm2 areal capacity. Recently, our group4,5 and several others6-8 have been developing new sulfur composite cathodes blended with transition metal sulfides (e.g., titanium and molybdenum disulfide), which not only provide good electronic and ionic conductivity, but assist in the trapping of polysulfides within the cathode. We have demonstrated that MoS2 doesn’t undergo a redox transition, unlike TiS2, and yet provides similar benefits. In addition, we have demonstrated similar improvement in the cycle life of sulfur cathodes with a thin coating of a metal sulfide. In this paper, we will describe our studies with high-areal-capacity sulfur cathodes blended or coated with new metal sulfides, demonstrating their performance and understanding their mechanism. Acknowledgements The work described here was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA) and supported by US Army-CERDEC. Y. Yin, S. Xin, Y. Guo and L. Wan, Angew. Chem. Int. Ed. 2013, 52, 13186 (2013).X. Ji, K. T. Lee, L. F. Nazar, Nat. Mater. 8, 500 (2009).A. Manthiram, S.-H. Chung, C. Zu, Adv. Mater. 27, 1980 (2015).R. Bugga, S. Jones, J. Pasalic, D. Addison and R. Thillaiyan, 228th ECS Meeting, Phoenix, AZ, Oct. 11 (2015).R. V. Bugga, S. C. Jones, J. Pasalic, C. S. Seu, J. P. Jones and L. Torres, J. Electrochem. Soc., 164 (2) A1-A12 (2016)L. Ma, S. Wei, H. L. Zhuang, K.E. Hendrickson, R. G. Hennig and L. A. Archer, J. Mater. Chem. A, 3, 19857 (2015).P. T. Dirlam, et al., ACS Appl. Mater. Interfaces, 8, 13437 (2016).X. Tao, J. Wang, C. Liu, H. Wang, H. Yao, G. Zheng, Z. Seh, Q. Cai, W. Li, G. Zhou, 981 C. Zu, and Y. Cui, Nature Comm., April 2016; Q. Zhang, Y. Wang, Z. Seh, Z. Fu, 982 R. Zhang, and Y. Cui, Nano Lett., 15, 3780 (2015).

Primary Batteries for Emerging Deep Space Exploration Missions

Primary batteries have played a critical role in past deep space planetary exploration missions, providing power to spacecraft such as the Galileo and Huygens Probes [1,2]. Most of these missions were of relatively short duration (Huygens lasted 2.5 hours), and relied on primary battery power alone to execute mission profiles. Future missions planned by the National Aeronautics and Space Administration (NASA) to the outer planets (Jupiter, Saturn) and their moons (Europa, Enceladus, Titan) will require more advanced primary batteries to provide bus power for days or even weeks. These batteries may be stored for several years during an initial cruise period, followed by operation in temperature extremes coupled with exposure to high radiation doses. The requirement for primary batteries with very high specific energy, low self-discharge/long calendar life performance, wide temperature operation and radiation tolerance has prompted the evaluation by NASA of commercially available options, as well as the development of new components and cell designs. This includes higher specific energy battery chemistries such as Li/CFx and Li/CFx-MnO2, which provide for a higher capacity per unit mass at moderate rates, relative to Li/SO2 and Li/SOCl2 chemistries used in previous missions. Current efforts to evaluate the effects of radiation and storage on these primary battery chemistries will be discussed in relation to future NASA needs. ACKNOWLEDGEMENT The work described here was carried out at the Jet Propulsion Laboratory, California Institute of Technology under contract with the National Aeronautics and Space Administration (NASA). L.M. Hofland, E.J. Stofel, R.K. Taenaka, Aerospace and Electronic Systems Magazine IEEE, 11, 14 (1996). B.P. Dagarin, R.K. Taenaka, E.J. Stofel, Proc. of 31st Energy Conversion Engineering Conference 1996, 1, 427 (1996).

The Performance Evaluation of High Specific Energy 18650-Size Lithium-Ion Cells for the Planned Europa Clipper Mission

NASA is planning to launch a mission to perform a detailed reconnaissance of the Jovian icy moon Europa. This mission, entitled the Europa Clipper, would involve a Jupiter-orbiting spacecraft that performs a science investigation of the surface during multiple flybys of the moon by utilizing a number of instruments, including an ice-penetrating radar that is intended to measure the thickness of the icy shell and the possible presence of a subsurface ocean. Ultimately, one objective of future missions to icy moons is to determine their habitability for life. The destination of Europa presents a number of technical challenges, since the spacecraft would be exposed to harsh radiation and extreme temperature environments. Furthermore, to comply with planetary protection protocols, the spacecraft would need to be sterile to avoid any potential contamination. The baseline power subsystem architecture for the Europa Clipper mission involves the use of solar arrays, power management electronics, and a rechargeable lithium-ion battery. 1 The preliminary design involves the use of high specific energy small 18650-size Li-ion cells that are assembled into large capacity multi-string batteries. This design approach capitalizes upon the presence of internal cell safety devices, excellent cell-to-cell reproducibility, and the fact that individual cell monitoring and balancing circuitry is not required. To meet the challenging mission requirements, we are currently evaluating a number of potential cell chemistries that could deliver the desired performance. Promising candidates should provide (i) good tolerance to high levels of radiation, (ii) good performance characteristics over a wide temperature ranges, and (ii) excellent storage life characteristics, since the cruise period to Europa is extremely long and could potentially be over 6.5 years in duration, depending upon the launch vehicle selected. In order to demonstrate the viability of candidate 18650-size Li-ion cells for use, a number of performance tests have been performed, including the following: (i) 100% DOD cycling under various conditions, (ii) charge and discharge rate characterization over a range of temperatures, (iii) short term storage tests at high temperatures, (iv) long-term storage tests at +25oC and 0oC, (v) module level 100% DOD cycle life testing at +20oC, (vi) module level long term storage testing at 0oC, and (vii) characterization after exposure to gamma-irradiation (60Co source). A number of these tests are focused upon establishing the long-term storage characteristics, with emphasis upon storing the cells on the bus at a partial state of charge at a fixed potential to mimic the spacecraft environment.2 Effort was also devoted to determining if the cell-to-cell voltage dispersion within 8-cell strings diverges when subjected to cycling and/or long term storage.3 As previously mentioned, the cell chemistries must be able to tolerate high doses of radiation, and there is some concern that performance loss may be observed due to the presence of organic electrolyte solutions and polymer binders and separators.4,5 To address this, cells were incrementally exposed to high levels of gamma-radiation using a 60Co source, and periodically characterized in terms of the capacity and impedance. In summary, promising candidate cell chemistries have been identified, and the test program implemented is essential to enable proper end of life performance projections and appropriate battery sizing ACKNOWLEDGEMENT The work described here was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA) and supported by the Europa Clipper Mission. REFERENCES 1. A. Ulloa-Severino, G. A. Carr, D. J. Clark, S. M. Orellana, R. Arellano, M.C. Smart, B.V. Ratnakumar, A. Boca, and S. F. Dawson, “Power Subsystem Approach for the Europa Mission”, 11th European Space Power Conference (ESPC), October 5, 2016. 2. B. V. Ratnakumar, M. C. Smart, and L. D. Whitcanack, “Storage Characteristics of Lithium-Ion Cells”, ECS Transactions, 25 (36), 297-306 (2010). 3. F. C. Krause, A. Lawrence, M. C. Smart, S. F. Dawson, A. Ulloa-Severino, and B. V. Ratnakumar, “Evaluation of Commercial High Energy Lithium-Ion Cells for Aerospace Applications”, 227th Meeting of the Electrochemical Society, #47580, May 28, 2015. 4. B. V. Ratnakumar, M. C. Smart, L. D. Whitcanack, E. D. Davies, and K. B. Chin, “Behavior of Li-Ion Cells in High-Intensity Radiation Environments”, J. Electrochem. Soc., 151 (4), A652- A659 (2004). 5. B. V. Ratnakumar, M. C. Smart, L. D. Whitcanack, E. D. Davies, K. B. Chin, F. Deligiannis, and S. Surampudi, “Behaviour of Li-Ion Cells in High-Intensity Radiation Environments: II. Sony/AEA/ComDEV Cells”, J. Electrochem. Soc., 152 (2), A357- A363 (2005).

Electrification and Decarbonization of the Chemical Industry

Zachary Schiffer is currently a doctoral student in the Chemical Engineering Department at MIT. An NSF Graduate Research Fellow and an MIT Presidential Fellow, he is studying applications of electrochemistry to the nitrogen cycle in the Manthiram Lab. Zachary received a B.S.E. from Princeton University in Chemical and Biological Engineering with minors in applications of computing and materials science. As an undergraduate, he worked in Dr. Craig Arnold's lab studying the coupling of mechanics and electrochemistry in lithium ion batteries. Karthish Manthiram is an Assistant Professor of Chemical Engineering at MIT. The Manthiram Lab develops technologies that enable modular and sustainable transformations of molecules. The lab is currently focused on the conversion of distributed feedstocks, such as air, water, carbon dioxide, and renewable electricity, into molecules that have an impact on our everyday lives. Examples include catalytic technologies through which farmers in developing countries can produce their own ammonia fertilizers and conversion of carbon dioxide into methanol to mitigate emissions that would otherwise contribute to global warming. Karthish received his bachelor's degree from Stanford University in 2010 and his Ph.D. from UC Berkeley in 2015, both in Chemical Engineering. Most recently, he was a postdoctoral researcher at the California Institute of Technology.

Factors Limiting Li+ Charge Transfer Kinetics in Li-Ion Batteries

To improve the power performance of Li-ion batteries, it is important to understand the factors that limit the Li+ charge transfer kinetics. Li-ion batteries comprised of graphite anode and lithium cobalt oxide cathode in an electrolyte made of 1 M LiPF6 in EC-DMC-DEC carbonate solvent mixtures could not deliver their room temperature capacity at a rate of C/2 at -30 and -40 oC [1]. When DEC was replaced by linear ester solvent, such as ethyl acetate (EA) or methyl butyrate (MB), the Li-ion batteries at -30 and -40 oC could deliver over 80% of their room temperature capacity at the same rate [2]. When the LiPF6 salt is replaced by LiBOB in EC-EMC (1:1 wt. ratio) carbonate solvent mixture, the impedance of graphite-electrolyte interface measured using graphite/Li half cells in the electrolyte with LiBOB is 3 times that in the electrolyte with LiPF6 [3]. These examples show that the electrolyte components play crucial roles in affecting Li+ charge transfer kinetics in Li-ion batteries. The Li+ charge transfer process starts from the solvated Li+ in the electrolyte to the reception of an electron (e-) from the electrode. This involves the de-solvation step of Li+ before entering into SEI and the diffusion step of Li+ through the SEI at the electrode and electrolyte interfaces before receiving an e- from the electrode at the electrode and SEI interface. Abe et al. [4-6] believe that the Li+ desolvation is the rate limiting step, which is supported by the results from the investigation of the electrolytes of different solvent systems using LiClO4 salt at HOPG, Li4Ti5O12 and Li+ solid conductors interfaces. The question is whether the de-solvation as a limiting step can be extended to the cathode-electrolyte interface. Jow et al. [7] examined the Li+ charge transfer kinetics at the graphite anode-electrolyte interface (SEI) and LiFePO4 (LFP) cathode-electrolyte interface (CEI) in a full cell, LFP/Gr, with Li as a reference electrode in 1 M LiPF6 in EC-DMC-MB with VC as an additive. It is found that the activation energy (Ea) at the graphite-electrolyte is about 67 kJ mol-1, which is much higher than 33 kJ mol-1 found at the LFP-electrolyte interface. It is concluded that the electrodes and their associated electrode-electrolyte interfacial layers are controlling the Li+ charge transfer kinetics. The impact of additives such as VC, LiBOB, and LiFSI, etc. on the impedance of the anode-electrolyte and the cathode-electrolyte interfaces in LiNiCoAlO2/Gr cylindrical cells in 1.0 M LiPF6 in EC-EMC-MP (20:20:60 vol %), where MP is methyl propionate, at low temperatures was studied by Jones et al. [8]. It is found that the additive impacts the impedance at the anode differently from that at the cathode. Further, we also found that the additives impact the Ea of Li+ charge transfer differently at the anode-electrolyte and the cathode-electrolyte interfaces. Different electrolyte components, including additives, result in different reduction and oxidation reactions during cell formation and cycling at the anode and cathode [9] and therefore, different and SEI and CEI layers. A discussion regarding the conditions in which the de-solvation step or the Li+ diffusion in either SEI or CEI layer is limiting the kinetics will also be provided. Acknowledgement Some work described here was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA). References M. C. Smart, B. V. Ratnakumar, and S. Surampudi, J. Electrochem. Soc., 1999, 146(2), 486-492. S. Herreyre, O. Huchet, S. Barusseau, F. Peron, J. M. Bodet, Ph. Biensan, J. Power Sources, 2001, 97-98, 576. K. Xu, J. Electrochem. Soc., 2008, 155(10), A733-A738. T. Abe, H. Fukuda, Y. Iriyama, Z. Ogumi, J. Electrochem. Soc., 2004, 151(8), A1120-A1123. Y. Ishihara, K. Miyazaki, T. Fukutsuka, T. Abe, ECS Electrochemistry Lett., 3 (8) A83-A86 (2014). T. Abe, F. Sagane, M. Ohtsuka, Y. Iriyama, and Z. Ogumi, J. Electrochem. Soc., 2005, 152(11), A2151-A2154. T. R. Jow, M. B. Marx, J. L. Allen, J. Electrochem. Soc., 2012, 159 (5), A604-A612. J.-P. Jones, M. C. Smart, F. C. Krause, B. V. Ratnakumar, E. J. Brandon, ECS Trans., 2017, 75, 1-11. S. A. Delp, O. Borodin, M. Olguin, C. G. Eisner, J. L. Allen, T. R. Jow, Electrochimica Acta, 2016, 209, 498-510.

C&EN’s Talented 12

TALENTED 12 C&EN’s Talented 12 ShareShare onFacebookTwitterWechatLinked InRedditEmail C&EN, 2017, 95 (33), pp 40–41August 21, 2017Cite this:C&EN 95, 33, 40-41(Credit: C&EN/Shutterstock)Figure1of1Welcome to the third annual Talented 12 issue. It took us months of scouring the globe to collect all 12 of the rising stars in chemistry featured in the pages that follow.The dream team we’ve assembled is tackling some of the toughest scientific challenges facing the world today. These young scientists are battling the opioid epidemic, inventing new medicines and better ways to make them, and harnessing sunlight to make fuel and other useful chemicals.To find our 12, we called on a panel of esteemed advisers, C&EN’s advisory board, and Talented 12 alumni to nominate prospects aged 42 or younger who are pushing the boundaries in their fields. We also accepted nominations from readers through an online form. Finally, we researched and evaluated the more than 150 candidates amassed during this process to zero in on the path-paving individuals highlighted here.We’re certain these 12 will be scientific MVPs someday. You should collect their autographs now.Our advisers: Frances H. Arnold, California Institute of Technology; James J. De Yoreo, University of Washington and Pacific Northwest National Laboratory; Anthony Estrada, Denali Therapeutics; Paula T. Hammond, Massachusetts Institute of Technology; Sarah E. Reisman, Caltech; Tobias Ritter, Max Planck Institute for Kohlenforschung; Daniel Siegwart, University of Texas Southwestern Medical Center; Alex Spokoyny, University of California, Los Angeles; Karen L. Wooley, Texas A&M University; Vivian W.-W. Yam, University of Hong Kong. In brief Profiles P.42–57 Talented 12 by the numbers P.46 Laboratory lovesP.52 Talented 12 alumni: Where are they now?P.58