Within days of arriving at Oxford University in 1981, South African chemist Michael Thackeray made a remarkable discovery that was eventually to have deep implications for the development of the lithium battery. Batteries International historian Kevin Desmond reports.
The long and fruitful road to Argonne
The energy storage business certainly has its strange facets. One is a quirk of geography. Why, for example, has some of the strongest research into lead acid batteries been conducted in Sofia, Bulgaria rather than techno-hub outside London or New York?
So too why has South Africa an outstanding reputation when it comes to studying — and developing — alternative battery chemistries? Think Johan Coetzer and the Zebra battery, for example. And also think Michael Thackeray, a contemporary of Coetzer, and his groundbreaking work on lithium batteries.
Michael Makepeace Thackeray was born in Pretoria, South Africa in January 1949. (To those who know their Victorian novelists his name reveals his lineage, he is a descendant of William Makepeace Thackeray, who is best known for Vanity Fair.) His parents, David and Mary Thackeray, had emigrated from England in 1947 and David was eventually to become director of the Radcliffe Observatory, at the time home to the largest 74-inch reflecting telescope in the southern hemisphere.
he young Thackeray did well throughout school but — as was compulsory at that time — had to spend a year in the South African Army before continuing his studies. He enrolled at the University of Cape Town in 1968 to study chemistry. Uncertain of where a degree in science would lead him, Thackeray recalls a moment in his second year during a crystallography class in the Geology Department when he felt a strong connection to the beauty of the crystalline world, gemstones and the history of the earth.
“I was enticed to UCT’s Chemistry Department, where professor Luigi Nassimbeni, an outstanding lecturer, convinced me of the importance that crystallography could play in practical materials science and structure-property relationships,” he recalls.
Hesitant of the future importance of crystallographic organo-metallic chemistry — the subject of his master’s thesis — Thackeray left academia and headed for South Africa’s major national laboratory, the Council for Scientific and Industrial Research (CSIR), where he joined the Crystallography Division of the National Physical Research Laboratory (NPRL) in Pretoria, his home town.
Thackeray started work at the CSIR in August 1973. He had a promising and opportune start, quickly unravelling two light atom structures that had eluded the efforts of others.
Realizing that he was the right age to travel before getting bogged down in a career, Thackeray gambled and asked his supervisor, Geoff Gafner, if he could take a year’s unpaid leave.
Gafner was generously supportive, saying ‘We’ll hold your job for you — see you in a year’s time!’ So at the end of January 1974, Thackeray headed for Durban where he joined a young Swedish yachtsman and his girlfriend who were sailing around the world. He hitched a ride to Cape Town — a seven day trip with gale force winds and mountainous waves, windless moments in becalmed, mirror-like seas and a near collision with a fishing fleet on approaching Cape Town.
In Cape Town, he collected (and married!) long-standing girlfriend Lisa Suzanne Kreft — before travelling around Europe for six months on an extended honeymoon in a makeshift van, and returning penniless to South Africa in December 1974.
Thackeray resumed his career at the CSIR in January 1975, by which time Johan Coetzer had also returned to CSIR’s Crystallography Division after a short break managing his family’s farm in Pongola, Natal.
The time coincided with the first oil crisis in the Middle East, which spawned intense worldwide efforts to find other forms of energy storage besides fossil fuels, notably rechargeable batteries. By the time Thackeray returned, Coetzer had initiated studies of silver-ion solid electrolytes that showed anomalously high ionic conductivity at room temperature.
Thackeray used this project for a PhD thesis (which he finished in 1977) while Coetzer embarked on high-temperature studies of lithium-sulphur and sodium-sulphur cells, embedding the sulphur in the pores of a zeolite matrix in attempts to reduce corrosion and enhance the safety of the cells.
Thackeray assisted Coetzer and, in a parallel effort, initiated an investigation of high temperature lithium-metal oxide cells.
Coetzer’s and Thackeray’s studies heralded the start of a 20-year period when CSIR and South Africa would make major contributions to electrical energy storage concepts and technologies. Their early studies also received the attention of South African industry, De Beers and Anglo American Corporation, the mining giants of diamonds and precious metals.
Imagining the possibility of mass electrified transportation by the turn of the century, De Beers and Anglo American joined and supported CSIR’s efforts to develop advanced high energy batteries.
By 1980, significant progress had been made at CSIR. Coetzer’s high temperature sodium-zeolite sulphur concepts had been redirected to sodium-iron chloride chemistry that was compatible with a conventional sodium-sulphur cell design in which a solid sodium-ion conducting solid electrolyte, beta-alumina, was used to separate the molten sodium and sulphur electrodes.
By contrast, in the sodium-iron chloride cell, later code-named the ‘Zebra’ cell, the solid beta-alumina ceramic was used to separate the molten sodium electrode from a solid iron chloride electrode and a molten sodium ion conducting electrolyte, NaAlCl4.
Meanwhile, Thackeray’s high temperature studies of lithium-transition metal oxide cells had revealed that iron oxide electrodes showed remarkable electrochemical stability, operating by reversible lithium insertion/iron extrusion reactions into/from a stable oxygen close-packed array to yield metallic iron and lithia (Li2O) via intermediate spinel and rock salt phases.
Because lithium/iron oxide cells (1.1V) provided a lower voltage relative to ‘Zebra’ sodium/iron chloride cells (2.35V) and subsequently sodium/nickel chloride cells (2.6V), De Beers and Anglo American opted to focus on sodium batteries rather than lithium technology.
By the early 1990s, in partnership with Germany’s Daimler Benz and Beta R&D from the UK, Zebra batteries had been demonstrated in electric vehicles. These batteries are still being produced by FIAMM for electric fleets in Europe, and by General Electric in the US, for stationary energy storage applications under the brand name Durathon.
Despite the progress being made by his CSIR colleagues in high-temperature sodium-metal chloride technology, Thackeray was more drawn to lithium electrochemistry.
“It offered greater prospects for undertaking crystallographic studies of electrode materials and for probing structural phenomena during electrochemical lithium insertion reactions. Moreover, at that time, the first generation of room temperature, primary (non-rechargeable) lithium cells was being produced by industry,” he recalls.
In late 1980, with the support of CSIR, the South African Inventions and Development Corporation) and Anglo American, Thackeray applied to John Goodenough, a professor at Oxford to spend a post-doctoral period with him to learn the art of room temperature lithium electrochemistry. Goodenough had recently pioneered the discovery of LiCoO2 as a lithium insertion electrode.
Goodenough responded warmly with an invitation for the visit.
The dreaming spires
Thackeray arrived at Oxford in October 1981, with his wife and daughters Caryn and Anna and found accommodation in Wolvercote on the outskirts of the city. It was to be the start of one of the most intellectually stimulating periods of his life.
Because his earlier research at CSIR on the electrochemical behaviour of iron oxide electrodes in high-temperature lithium cells had shown that, in the charged state, iron oxide spinel structures were formed, Thackeray had arrived in Oxford with several spinel samples in his possession, including magnetite, Fe3O4, and hausmannite, Mn3O4.
“At my first meeting with Goodenough, I suggested my research plan to investigate the electrochemical behaviour of spinels at room temperature. Goodenough responded gently with the comment, ‘Well, you do know that spinels are like gems, stable line-phases … so where is the space in the structure to accommodate the inserted lithium ions during discharge? By all means try, but I suggest that you look around the laboratory to see what other projects are going on.”
The mineral ‘spinel’ (MgAl2O4) is a semi-precious gem, one of the most famous being the mistaken Black Prince’s ruby, dating back to the 14th century, which is positioned above South Africa’s Cullinan II diamond on one of the British Crown Jewels.
Goodenough then left for a visit to India, returning some two weeks later.
Thackeray immediately set to work, first conducting a chemical reaction of lithium with Fe3O4 at room temperature to mimic the electrochemical reaction. To his delight, Thackeray observed that the magnetic Fe3O4 particles, which clung to the magnetic stirrer in the reaction vessel, gradually fell away from the stirrer on the addition of the lithium reagent, n-butyl-lithium — evidence of iron reduction and reaction between lithium and the spinel structure.
On obtaining the powder X-ray diffraction pattern and a compositional analysis of the lithiated product, Thackeray determined that, on lithiation, the cubic unit cell of the Fe3O4 host structure had expanded by approximately 3% and that there were changes in the relative intensities of the diffraction peaks, confirming the lithium insertion process.
On John Goodenough’s return from India, Thackeray bumped into him close to the laboratory where the experiment had been conducted.
“I told him that lithium was indeed going into the spinel, Fe3O4. Goodenough immediately laid his hand on my shoulder and led me into his office, saying ‘Sit down, tell me all.’”
A few days later, Bill David, a highly talented physicist and crystallographer from the nearby Clarendon Laboratory, who had also recently joined John Goodenough’s research team, introduced himself to Thackeray — he had heard of the Fe3O4 results from Goodenough. David had access to the ‘Wiseman’ computer program — software written by Phil Wiseman, who had worked on Goodenough’s earlier LiCoO2 project, to undertake structural refinements of powdered materials with X-ray diffraction data.
Refinement of the LixFe3O4 data, showed that during the lithiation of magnetite, Fetet[Fe2]octO4, the [Fe2]octO4 spinel framework (with iron in octahedral sites) had remained intact, whereas, the iron that resided in tetrahedral sites outside the framework were displaced into neighboring empty octahedral sites to make place for the uptake of one lithium ion to generate a rock salt structure (LiFe)oct[Fe2]octO4; i.e., without iron extrusion as in high-temperature cells.
Thackeray and David reported the results of the refinement to Goodenough with similar findings for hausmannite (Mn3O4) that, on lithiation, formed the corresponding ordered rocksalt structure (LiMn)oct[Mn2]octO4.
The results had immediate scientific and technological implications.
Goodenough, familiar with the spinel structure from his earlier research on their magnetic properties, suggested an investigation of the lithium spinel Litet[Mn2]octO4, which accommodated lithium by the same principle as Fe3O4 and Mn3O4 to form the ordered rocksalt configuration (Li2)oct[Mn2]octO4; in this case, the interstitial space of the [Mn2]octO4 spinel framework contained only lithium ions that could migrate, unimpeded, through a three-dimensional network of face-sharing tetrahedra and octahedra, providing fast kinetics and a high power electrode.
This reaction occurred electrochemically at 3V in a lithium cell. Because the concept of spinel electrodes had originated at CSIR, Goodenough graciously agreed to cede title of the spinel patent that was filed to SAIDCOR, one of the South African sponsors of Thackeray’s visit to Oxford, later to be licensed to industry.
Over recent years, Li[Mn2]O4 has been widely exploited. It is often used as a blend in the cathodes of lithium-ion batteries, notably for portable electronics and electric vehicles, such as the all-electric Nissan Leaf and the hybrid-electric Chevy Volt.
Shortly after the discovery that spinel structures could act as insertion compounds for lithium at room-temperature, Peter Bruce, an electrochemist from the University of Aberdeen joined the Oxford team, contributing to the evaluation of the electrochemical properties of the electrodes. It was a golden 12 months, a happy band of four — each contributing to a shared and impactful outcome of spinel research in different ways.
Some 30 years on, the four scientists are still in close communication with one another.
Thackeray returned to South Africa at the end of 1982. The Zebra team was on the verge of leaving the CSIR site to become an Anglo American owned company, Zebra Power Systems, outside Pretoria.
Thackeray remained at CSIR, where he established a new battery team to build on the lithium battery materials research he had initiated, while providing R&D support to the South African battery industry, including among others, Zebra Power Systems, Willard Batteries, a producer of lead-acid batteries, and Delta EMD, a manufacturer of electrolytic manganese dioxide (EMD) for the alkaline (Zn/MnO2) battery market.
Over the next 10 years, Thackeray and his CSIR team continued to innovate the design of new lithium battery electrode materials, structures and compositions, first focusing, on his return from Oxford, on the family of lithium spinels containing manganese, vanadium or iron.
e demonstrated, in particular, that lithium could be extracted electrochemically from LiMn2O4 at an attractive 4V. In 1987, there were indications that Sanyo and Sony Corporation were starting to pay particular attention to the manganese spinel, LiMn2O4. By then, it had been established that stoichiometric LiMn2O4 had significant problems, notably manganese dissolution that resulted from the dissociation of trivalent manganese ions into soluble divalent ions and insoluble tetravalent ions.
Furthermore, lithium insertion into LiMn2O4 induced a severe crystallographic (Jahn-Teller) distortion that compromised the stability of the electrode particle surface and the reversibility of the reaction at 3V. Thackeray addressed these problems with Rosalind Gummow and Annemarie de Kock — they made significant improvements to the operational stability of LiMn2O4 by adding excess lithium (and other multivalent cations) to increase the average oxidation state of manganese in the starting spinel electrode above 3.5+.
In 1994, Ernst Ferg, Gummow, de Kock and Thackeray demonstrated that safe 2.5V lithium-ion cells could be fabricated by coupling a lithium titanate spinel anode (Li4Ti5O12), which operates 1.5V above the potential of metallic lithium, with high voltage cathodes, notably a stabilized Li1+xMn2-xO4 spinel — a system that is currently being exploited for devices requiring high power batteries, such as hybrid electric vehicles.
Recognizing the cost and stability advantages of manganese over cobalt and nickel oxide electrodes, the CSIR team adopted strategies to engineer and patent new lithium insertion materials, which included manganese oxide electrodes with one-dimensional, two-dimensional and three-dimensional pathways for lithium-ion transport; they were successful on all three counts, designing and evaluating lithia-stabilized alpha-MnO2, lithia-stabilized layered-MnO2 and lithia-stabilized spinel-MnO2 electrode materials, respectively.
Anhydrous layered MnO2 structures were unknown at the time.
Of particular significance was that Thackeray’s approach to use the layered rock salt structure of Li2MnO3 (Li2O•MnO2) as a precursor to fabricate a Li2MnO3-stabilized layered MnO2 electrode was the forerunner to further materials advances made by him and his team at Argonne National Laboratory a few years later.
While in South Africa, Thackeray was presented with several awards for his research contributions. In 1983, he was awarded a Silver Medal from the South African Institute of Physics for significant achievements for a scientist under the age of 35 for his seminal work on spinel electrodes.
In 1990, he received the CSIR Outstanding Achiever Award and three years later the International Battery Association Research Award for significant contributions to the development and understanding of manganese oxides and vanadium oxides.
Other awards followed. In 2005, Coetzer and Thackeray appeared as two of 11 notable South African scientists and innovators for contributions to world science and technology on the commemorative wall at Africa’s first internationally accredited science park: The Innovation Hub.
Indeed, visitors to the new Innovation Hub in Pretoria, South Africa, can drive down streets named after Michael Thackeray and Johan Coetzer.
The Argonne years
In 1992, despite the success of the lithium battery research being conducted, CSIR, decided to cut its further funding, ostensibly because there was no industry in South Africa to capitalize on the technology. CSIR management appeared oblivious of Sony’s introduction of the first lithium-ion battery products into the market in 1991, and the need for high energy batteries to power the impending boom of portable consumer electronics devices.
Here chance, or good fortune, intervened. At an Electrochemical Society Meeting in Toronto in October 1992, Thackeray met Don Vissers, head of the Battery Department at Argonne National Laboratory.
Unaware of Thackeray’s dilemma at CSIR, Vissers invited Thackeray to lead a materials R&D effort at Argonne for a new lithium-polymer battery project to be sponsored by the US Department of Energy and the United States Advanced Battery Consortium (USABC). Thackeray, sensing a bright future for lithium battery technology and recognizing an excellent opportunity, accepted.
He and his family packed their bags and left South Africa for Chicago in January 1994. The decision was not easy — it meant leaving close-knit family and friends in mid-life at a time when South Africa was undergoing daunting but exciting changes under Nelson Mandela’s leadership.
As with CSIR and Oxford, Thackeray got off to a quick start — within two months of his arrival, while working on a high energy, all solid state, lithium-polymer battery project for electric vehicles supported by the US Department of Energy, 3M Corporation and Hydro-Quebec, he had identified a lithia-stabilized vanadium oxide cathode material (based on his earlier research at CSIR) that provided the 3M/HQ cells with 30% more energy and superior power relative to the original material being used.
This materials technology was later transferred to, and scaled up by, 3M and implemented by Hydro-Quebec/Avestor in commercial battery products for stationary energy storage — however, subsequent problems related to lithium dendrite formation and short circuiting on long-term cycling ultimately led to the withdrawal of the batteries from the market.
During his early years at Argonne, Thackeray also received support from the Office of Basic Energy Sciences of the US Department of Energy. With Christopher Johnson and others, he used the funding to continue his unfinished research of lithia-stabilized alpha-MnO2, spinel-MnO2, and layered-MnO2 electrode structures.
Towards the end of the 1990’s, noticing that other research groups were initiating studies on Li2MnO3, Thackeray, Johnson, Khalil Amine, Jaekook Kim and an expanding Argonne team intensified their efforts to exploit composite ‘layered-layered’ xLi2MnO3•(1-x)LiMO2 (M=Mn, Ni, Co) and ‘layered-spinel’ xLi2MnO3•(1-x)LiM2O4 (M-Mn, Li, Ni, Co) electrode structures, which formed the basis of a broad patent portfolio.
Argonne’s intellectual property was subsequently licensed worldwide to major lithium battery materials and cell manufacturers. The first generation Chevy Volt, in particular, uses a lithium-ion battery with a blend of the Argonne composite materials and stabilized LiMn2O4 spinel in the cathode.
In March 2007, Thackeray received an invitation to meet George Bush, the US president, at the White House for discussions with eight others on his energy policy relating to lithium-ion batteries and bio-fuels. Also in attendance were Samuel Bodman, the energy secretary; Karl Rove, a former presidential senior adviser and deputy chief of staff; and Steven Chu, the future energy secretary in the Obama administration.
Thackeray highlighted the fact that the US had fallen way behind Japan, Korea and China in lithium-ion battery technology, despite the ability of the US to continually innovate in the field; that lithium-ion batteries were becoming a strategic commodity; and that it was necessary for US national laboratories, industry and academia to come together to address the issue, to play ‘catch up’ and narrow the technological gap.
President Bush looked at Thackeray and said “You are asking me for greater financial support?”
Thackeray replied in the affirmative.
The rest has become history. That conversation — albeit through a circuitous route and Thackeray was just one of the major players — ended in the most extensive US government funding for the research and commercialization of advanced batteries.
Much of the North American energy storage landscape that we see today is a result of this.
From workshop to practice
Thackeray subsequently wrote a white paper for the White House outlining a strategy to address the needs for lithium-ion battery technology.
Shortly thereafter, the US Department of Energy’s Office of Basic Energy Sciences held a workshop to identify the basic research needs and opportunities underlying batteries, capacitors, and related energy storage technologies, with a focus on new or emerging science challenges with potential for significant long-term impact on the efficient storage and release of electrical energy.
The workshop resulted in the instigation of five DOE Energy Frontier Research Centers on Energy Storage in 2009 of which one was awarded, under a five-year contract, to Argonne National Laboratory with Northwestern University and the University of Illinois at Urbana Champaign as institutional partners.
Thackeray was appointed director of the EFRC, the Center for Electrical Energy Storage — Tailored Interfaces. The mission of the center is to acquire a fundamental understanding of electrode/electrolyte phenomena that control electrochemical processes to enable dramatic improvements in the design of new electrode/electrolyte materials and architectures, and in lithium battery performance.
Since arriving at Argonne, Thackeray has been honored with many additional awards: the University of Chicago Distinguished Performance Medal for contributions to lithium battery technology (2003); the Electrochemical Society Battery Division Research Award (2005); an R&D100 Award: ‘Composite Electrode Materials for Plug-in Hybrid- and All-Electric Vehicle Batteries’ (2009); the US Department of Energy R&D Award — Office of Vehicle Technologies (2010); and the International Battery Association, Yeager Award for life-long achievements in lithium battery electrode materials research and development (2011).
Thackeray remains a distinguished fellow and senior scientist at Argonne. To date, he has published more than 200 scientific papers and is an inventor on 50 patents, several of which have been licensed on an international scale or sold to industry.
Thackeray, now 65, believes that there is still much more to be done by the next generation of chemists, physicists, materials scientists, theoreticians and engineers to push the envelope of battery science and technology in an interdisciplinary manner even further.
I’ve spent 35 years in the battery game and I have been extremely fortunate to have worked with, and learned from, some of the best and brightest minds, both young and old,” he says. “My experiences with lithium-ion technology can be likened to surfing a wave — a wave that is still building and has not yet broken.
“The challenges to increase the energy capacity of batteries further and to store the energy in smaller and smaller containers — safely will be difficult, but not insurmountable. This century will be about harnessing clean energy, a matter that is of growing environmental, economical and strategic importance for the future of the planet and humankind.”