Abstract
It is a privilege for me to write this brief perspective on the transition of John B. Goodenough from Oxford to the University of Texas at Austin (UT Austin). While most people will tend to retire, Goodenough transitioned to UT Austin at the age of 64 in 1986 and has been making phenomenal contributions during the past 35 years, with a genuine passion for science and profound impact on the society at large. To highlight a few, the contributions at UT Austin include the following: chemistry and physics of high-temperature copper oxide superconductors; battery electrodes and electrolytes, including polyanion family of oxide cathodes, niobium titanium oxide anode, and Prussian Blue cathode; alkali-metal plating/stripping; solid-state batteries; flow batteries; oxygen reduction/evolution reaction catalysts; and solid oxide fuel cell electrodes and electrolytes. Finally, what distinguishes Goodenough more than anything else is his unique personal attributes.
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As a physicist, John Goodenough worked closely with solid-state chemists uniquely at the interface between chemistry and physics of materials at Lincoln Laboratory, Massachusetts Institute of Technology, from 1952 to 1976. By bridging the gap between physics and chemistry, Goodenough made several critical contributions in the area of transition-metal oxides, including the development of random-access memory (RAM) for digital computers, Goodenough-Kanamori rules for magnetic interactions, and NASICON with a framework structure for fast alkali-metal-ion transport (Fig. 1). His grasp and deep fundamental understanding of the physics and chemistry of oxides is reflected in his monograph "Metallic Oxides." 1 The discoveries at Lincoln lab led to his election as a member of the U.S. National Academy of Engineering in 1976. Following the tradition of a solid-state chemist to head the Inorganic Chemistry Laboratory (ICL) at the University of Oxford, Goodenough was invited in 1976 to head the ICL at Oxford at the retiring of the well-known solid state-chemist J. S. Anderson.
Figure 1. The trajectory and hallmark of Nobel Laureate John B. Goodenough.
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Standard image High-resolution imagePrompted by the oil embargo in the 1970s, Goodenough started employing his solid-state chemistry and physics knowledge at Oxford to develop materials for alternative energy technologies, including photovoltaic solar energy harvesting, hydrogen fuel production by electrolysis, direct methanol fuels cells, and rechargeable batteries (Fig. 1). The demonstration by Whittingham of a rechargeable lithium battery with layered TiS2 cathode and a lithium-metal anode in 1976, 2 followed by the flurry of activities on layered transition-metal chalcogenides, caught Goodenough's attention towards lithium batteries. Recognizing the limited voltage (<2.5 V) of sulfide or other chalcogenide cathodes and the safety hazard posed by lithium-metal anode, Goodenough focused on exploring lithium-containing transition-metal oxides as cathodes for lithium batteries. This led to the development of three families of oxide cathodes in the 1980s, which are the only practical cathodes for lithium-ion batteries to date. 3 The effort involved working with Goodenough at Oxford three visiting scientists from three different parts of the world, who were on leave of absence from their jobs in their country and did not have any overlap among them. Koichi Mizushima from Japan worked on layered LiCoO2, 4 Michael Thackeray from South Africa on spinel LiMn2O4, 5 and Arumugam Manthiram from India on iron-based polyanion oxides. 6,7 Compared to the sulfides or chalcogenides, the oxide cathodes displayed a significant increase in cell voltage to ∼4 V.
The departure from sulfide and chalcogenide cathodes to oxide cathodes by Goodenough is rooted in his deep fundamental understanding of the crystal chemistry and the relative positions of the d bands of various transition-metal ions Mn+/(n+1)+ in solids. More specifically, it is based on his recognition of the rich, but complex, structural and chemical bonding factors that influence or determine the redox energies of various transition-metal ions, e.g., how do the various factors, such as the coordination geometry of metal ions, metal-oxygen bond lengths, and covalency of metal-oxygen bonds, influence the redox energies? The simple fact that the top of the O2−:2p band lies at a lower energy than the S2−:3p band led him to explore oxide cathodes so that one can have access to higher oxidation states and thereby increase the cell voltage (Fig. 2). With this in mind and looking for an oxide with a layered structure analogous to layered sulfides and already containing lithium in it, his research group first focused on layered LiCoO2. The reason to choose a layered oxide with Co rather than with another 3d transition metal to the left of Co in the early part of the 3d transition series (e.g., Ti, V, or Mn) is that the metal:3d band becomes progressively lowered in energy for a given oxidation state. It is such an in-depth basic science understanding that led Goodenough throughout his career to innovate with the design and development of electrode and electrolyte materials for batteries and fuel cells.
Figure 2. Qualitative energy diagram, illustrating the relative positions of the redox energies of transition-metal ions with respect to the top of the O2−:2p and S2−:3p bands, which limit the accessible cell voltage in a lithium cell.
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Standard image High-resolution imageThe Transition from Oxford to the University of Texas at Austin
I was fortunate to have the opportunity to join Goodenough at Oxford in November 1985 on leave from my position as a Lecturer in Chemistry at Madurai Kamaraj University in India. That was a turning point in my life. Without that opportunity, my personal life and professional career would have been entirely different, and I am immensely indebted to John forever. At Oxford, faculty have to retire when they become 65 years of old. Considering this, when the University of Texas at Austin (UT Austin) invited Goodenough to join as the Virginia Cockrell Centennial Chair in Engineering, Goodenough accepted the position in early 1986. Five months later after my arrival at Oxford, John told me "my boy, I am going to move to UT Austin in September 1986, so what do you want to do? Do you want to come with me or do you want to go back to India when I leave Oxford?" I did not know what to say as my wife and two years old daughter were in India. I thought about for a week and went and told John that I will go with him to UT Austin without even consulting with my wife as there was no phone at my home in India and it was too expensive those days to call India from England! That was one of the best decisions I made in my life!
John was provided with $300,000 as a start-up package by UT-Austin. He asked me and another postdoctoral fellow Ramasamy Manoharan, who moved with me to UT-Austin from Oxford, to make the necessary equipment purchase and set up the lab. Manoharan was an electrochemist by training and I was a solid-state chemist by training. Together, we were able to quickly transfer the laboratory experimental know-hows on lithium batteries and fuel cells from Oxford and set up the solid-state chemistry and electrochemistry lab at UT Austin with necessary basic facilities. Some of the research activities at UT Austin, particularly in the early years, are briefly highlighted below (Fig. 1).
Copper oxide superconductors and narrow-band oxides
As we began our journey at UT Austin, the news on the discovery of copper oxide superconductors with high superconducting transition temperatures Tc broke. John and I became quickly engaged on copper oxide superconductors, particularly to understand the confounding variations in the Tc of YBa2Cu3O7-δ from lab to lab and the factors that influence the Tc. We developed an iodometric chemical titration method to determine the oxidation state of copper and the oxygen content in copper oxides, 8 which became very effective to correlate the Tc to changes in hole concentration with cationic doping and processing conditions (Fig. 3). The work prolonged for a few years in understanding the structure-composition-property relationships in various copper oxide superconductors with cation doping, including La2CuO4, YBa2Cu3O7, Bi-Sr-Ca-Cu-O, Tl-Ba-Ca-Cu-O, Sr1-yNdyCuO2 systems. 9–11 John with Jianshi Zhou, who was a visiting student and then a postdoc, and is now a Research Professor at UT Austin, continued to focus on delineating the superconductivity mechanism in copper oxides as well as probing the localized to itinerant electron transition regimes in narrow-band oxides for a number of years at UT Austin. 12,13
Figure 3. John Goodenough and Arumugam Manthiram looking at the drastic variation in the oxygen content with temperature of the copper oxide superconductorYBa2Cu3O7-δ with a thermogravimetric analyzer (TGA) in 1987. Reprinted (adapted) with permission from ACS Energy Letters, Vol. 4, p. 2763, Copyright 2019 American Chemical Society.
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Standard image High-resolution imageBattery electrodes and electrolytes
Triumphed by the results of layered LiCoO2 and spinel LiMn2O4 at Oxford, John and I started at Oxford on iron-based polyanion oxides to reduce the cost further from Co and Mn. My PhD thesis work in India was on lower-valent molybdenum oxides, and as a fan of molybdenum oxides, I focused in early 1986 at Oxford on chemical lithium insertion reactions into the polyanion oxide Fe2(MoO4)3. 6 As we moved quickly from Oxford in September 1986, the work continued at UT Austin with a series of iron-based polyanion oxides Fe2(XO4)3 (X = Mo, W, and S). We found a significant increase in cell voltage to 3.0 V vs Li/Li+ in both Fe2(MoO4)3 and Fe2(WO4)3 and then to 3.6 V in Fe2(SO4)3, all having the same crystal structure and Fe2+/3+ redox couple, compared to the simple iron oxide Fe2O3 (< 2.5 V). 7 This led us to recognize the power of the inductive effect caused by the polyanion in drastically increasing the cell voltage by more than 1 V. The more covalent X-O bonds weaken the Fe-O bond covalence through inductive effect and thereby lowers the Fe2+/3+ redox energy and increases the cell voltage. The more covalent S-O bond compared to the Mo-O or W-O bonds weakens the Fe-O bond covalence even more, resulting in an increase in cell voltage from 3.0 V for X = Mo or W to 3.6 V for X = S. As we became too heavily engaged with the excitement in copper oxide superconductors, there was a disruption in the battery work, and a PhD student of Goodenough, Geeta Ahuja, continued the effort with titanium and niobium phosphates during 1987–1991.
I would like to point out that it was a great struggle in the early couple of years to collect the electrochemical data as a 4-channel battery cycler custom-built by an individual at Oxford would crash every other day, and I had to call Oxford to get advice or ask him to visit UT Austin from Oxford to fix it. Fortunately, I was able to contact Dr John Zhang at College Station and explain to him what we need for collecting the charge-discharge and cyclability data. Dr. Zhang built the first 4-channel battery cycler for us I think in 1988 and drove from College Station to Austin by himself to deliver the machine and set it up. As we all know, Dr. Zhang then founded Arbin in College Station in 1991 and Arbin cyclers are everywhere around the world now!
Figure 4. Arumugam Manthiram delivering the Nobel Prize Lecture on behalf of John Goodenough in Stockholm in 2019, while Goodenough is sitting in the audience and listening.
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While we had a good time with high productivity at UT Austin, Jean-Marie Tarascon offered me in 1990 a staff scientist position at Bellcore to work on lithium batteries. When I informed John, he responded "you are not an industry guy; if I explore a faculty position at UT Austin, would you be interested?" I said I was teaching in India, I love teaching, and if a faculty position is offered, I will stay here. A tenure-track assistant professor position was offered to me in the Department of Mechanical Engineering in September 1991 and ever since I have stayed at UT Austin. This is the other best decision I made in my life because of John's intuition and confidence in me! Rest is history!
In order to demonstrate my independence for tenure as alerted by the department, I detached myself from John's research activities. In the meantime, Sony Corporation announced the commercialization of lithium-ion batteries with layered LiCoO2 cathode and a carbon anode. This announcement as well as the above discovery of the power of the inductive effect of polyanions in the 1980s prompted a systematic investigation by John's group with other polyanion oxide cathodes, which led to the identification of olivine LiFePO4 cathode 10 years later in 1997. 14 The polyanion oxides have now become a broad family of electrodes with a range of structures and compositions for cells based on lithium, sodium, and multivalent ions with better thermal stability. 15
The work at UT Austin in Goodenough's group continues to date with several new or improved electrode materials for both lithium- and sodium-based batteries. Some notable examples are the framework TiNb2O7 (TNO) anode for lithium-ion batteries with a high capacity of around 300 mAh g−1, 16 low-cost Prussian blue cathodes for sodium-ion batteries, 17 etc. The work also includes extensive investigations of stable lithium and sodium plating and striping with both liquid and solid electrolytes, 18 all-solid-state lithium and sodium batteries, 19 redox flow batteries with solution electrodes, 20 electrocatalysts for oxygen reduction and oxygen evolution reactions in metal-air batteries, 21 etc.
Solid oxide fuel cell electrodes and electrolytes
Extending the broad knowledge in metal oxides, Goodenough's work at UT Austin also focused on developing electrodes and electrolytes for solid oxide fuel cells. With an aim to lower the operating temperature, the perovskite-based La1-xSrxGa1-yMgyO3-δ solid electrolyte with lower operating temperatures of ∼700 °C was developed. 22 With an aim to develop anodes with more tolerance to sulfur impurity in hydrocarbon fuels, the double perovskite was identified. 23
Personal Traits
The contributions of John Goodenough with breadth and depth in the areas of solid-state science and electrochemistry is well-known to the community and needs not much elaboration. He is one of the greatest scientific minds of our time. His trademark is interdisciplinarity. He has been a strong force to bridge the chemistry and physics of materials throughout his career for seven decades with a profound technological and societal impact. His contributions were recognized in 1989 by the Von Hippel Award of the Materials Research Society (MRS), the highest award of MRS. Ever since, many like me in the community were fondly hoping and expecting the announcement of Nobel Prize in Physics or Chemistry for John. Years passed by with little bit of disappointment in the Fall of every year, and thank God, it finally happened in the Fall of 2019. It was a joy for many around the world! I was fortunate and humbled to deliver John's Nobel Prize Lecture in Stockholm in December 2019 (Fig. 4).
However, this article will be incomplete without the recognition of John's other side, his unique personal attributes. I had the distinct opportunity to see him on a daily basis for 36 years, except during the COVID hassle, as his office is two doors from mine. When he walks by in the morning to his office, he would say "Good Morning, Ram," and that would blossom my day! He always has a sense of purpose. He is thoughtful and curious. He is a good listener with love and respect for everyone. He is humble, and always looks for learning from others, including any student, even at this age. Anyone can talk to him about any topic at any time; yes, he will entertain you with that laugh! He never gets stressed out; even when there are challenges ahead, his attitude is "one step at a time." He makes sure that he sleeps 8 h a day so that his mind is clear and fresh for the day ahead. He has a high moral standard. His philosophy is "always be honest about what you do and what you say, and leave the rest to the Lord." He is a role model to everyone not only in science, but also in our daily life. He is inspirational to everyone, including me.
Conclusions
The Oxford—UT Austin transition at the age of 64 has been a remarkable 35 years at UT Austin for John Goodenough. The transition made possible the training, nurturing, and mentoring of many students and postdoctoral fellows from different parts of the world, with new discoveries and high productivity. The fields of solid-state science and electrochemistry have benefited greatly with a strong driving force from Goodenough to bridge the chemistry and physics of materials. His thinking and unique perspectives through numerous impactful publications and discoveries have shaped the community. More importantly, his personal traits with humbleness, good listening, and respect to everybody is a lesson for scientific success. With a standing ovation, we look forward to his 100th Birthday!
Acknowledgments
I am deeply indebted to John forever for the opportunity, freedom, and mentoring he provided; without that opportunity, my life would have been entirely different! I also acknowledge the support of the Welch Foundation grant F-1254.