Who Really Invented the Rechargeable Lithium-Ion Battery?

Fifty years after the birth of the rechargeable lithium-ion battery, it&#;s easy to see its value. It&#;s used in billions of laptops, cellphones, power tools, and cars. Global sales top US $45 billion a year, on their way to more than $100 billion in the coming decade.

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And yet this transformative invention took nearly two decades to make it out of the lab, with numerous companies in the United States, Europe, and Asia considering the technology and yet failing to recognize its potential.

The first iteration, developed by M. Stanley Whittingham at Exxon in , didn&#;t get far. It was manufactured in small volumes by Exxon, appeared at an electric vehicle show in Chicago in , and served briefly as a coin cell battery. But then Exxon dropped it.

Various scientists around the world took up the research effort, but for some 15 years, success was elusive. It wasn&#;t until the development landed at the right company at the right time that it finally started down a path to battery world domination.

Did Exxon invent the rechargeable lithium battery?

Akira Yoshino, John Goodenough, and M. Stanley Whittingham [from left] shared the Nobel Prize in Chemistry. At 97, Goodenough was the oldest recipient in the history of the Nobel awards. Jonas Ekstromer/AFP/Getty Images

In the early s, Exxon scientists predicted that global oil production would peak in the year and then fall into a steady decline. Company researchers were encouraged to look for oil substitutes, pursuing any manner of energy that didn&#;t involve petroleum.

Whittingham, a young British chemist, joined the quest at Exxon Research and Engineering in New Jersey in the fall of . By Christmas, he had developed a battery with a titanium-disulfide cathode and a liquid electrolyte that used lithium ions.

Whittingham&#;s battery was unlike anything that had preceded it. It worked by inserting ions into the atomic lattice of a host electrode material&#;a process called intercalation. The battery&#;s performance was also unprecedented: It was both rechargeable and very high in energy output. Up to that time, the best rechargeable battery had been nickel cadmium, which put out a maximum of 1.3 volts. In contrast, Whittingham&#;s new chemistry produced an astonishing 2.4 volts.

In the winter of , corporate managers summoned Whittingham to the company&#;s New York City offices to appear before a subcommittee of the Exxon board. &#;I went in there and explained it&#;5 minutes, 10 at the most,&#; Whittingham told me in January . &#;And within a week, they said, yes, they wanted to invest in this.&#;

Whittingham&#;s battery, the first lithium intercalation battery, was developed at Exxon in using titanium disulfide for the cathode and metallic lithium for the anode.Johan Jarnestad/The Royal Swedish Academy of Sciences

It looked like the beginning of something big. Whittingham published a paper in Science; Exxon began manufacturing coin cell lithium batteries, and a Swiss watch manufacturer, Ebauches, used the cells in a solar-charging wristwatch.

But by the late s, Exxon&#;s interest in oil alternatives had waned. Moreover, company executives thought Whittingham&#;s concept was unlikely to ever be broadly successful. They washed their hands of lithium titanium disulfide, licensing the technology to three battery companies&#;one in Asia, one in Europe, and one in the United States.

&#;I understood the rationale for doing it,&#; Whittingham said. &#;The market just wasn&#;t going to be big enough. Our invention was just too early.&#;

Oxford takes the handoff

In , John Goodenough [left] joined the University of Oxford, where he headed development of the first lithium cobalt oxide cathode.The University of Texas at Austin

It was the first of many false starts for the rechargeable lithium battery. John B. Goodenough at the University of Oxford was the next scientist to pick up the baton. Goodenough was familiar with Whittingham&#;s work, in part because Whittingham had earned his Ph.D. at Oxford. But it was a paper by Whittingham, &#;Chemistry of Intercalation Compounds: Metal Guests in Chalcogenide Hosts,&#; that convinced Goodenough that the leading edge of battery research was lithium. [Goodenough passed away on 25 June at the age of 100.]

Goodenough and research fellow Koichi Mizushima began researching lithium intercalation batteries. By , they had improved on Whittingham&#;s design, replacing titanium disulfide with lithium cobalt oxide. The new chemistry boosted the battery&#;s voltage by another two-thirds, to 4 volts.

Goodenough wrote to battery companies in the United States, United Kingdom, and the European mainland in hopes of finding a corporate partner, he recalled in his memoir, Witness to Grace. But he found no takers.

He also asked the University of Oxford to pay for a patent, but Oxford declined. Like many universities of the day, it did not concern itself with intellectual property, believing such matters to be confined to the commercial world.

Goodenough&#;s battery replaced Whittingham&#;s titanium disulfide in the cathode with lithium cobalt oxide.Johan Jarnestad/The Royal Swedish Academy of Sciences

Still, Goodenough had confidence in his battery chemistry. He visited the Atomic Energy Research Establishment (AERE), a government lab in Harwell, about 20 kilometers from Oxford. The lab agreed to bankroll the patent, but only if the 59-year-old scientist signed away his financial rights. Goodenough complied. The lab patented it in ; Goodenough never saw a penny of the original battery&#;s earnings.

For the AERE lab, this should have been the ultimate windfall. It had done none of the research, yet now owned a patent that would turn out to be astronomically valuable. But managers at the lab didn&#;t see that coming. They filed it away and forgot about it.

Asahi Chemical steps up to the plate

The rechargeable lithium battery&#;s next champion was Akira Yoshino, a 34-year-old chemist at Asahi Chemical in Japan. Yoshino had independently begun to investigate using a plastic anode&#;made from electroconductive polyacetylene&#;in a battery and was looking for a cathode to pair with it. While cleaning his desk on the last day of , he found a technical paper coauthored by Goodenough, Yoshino recalled in his autobiography, Lithium-Ion Batteries Open the Door to the Future, Hidden Stories by the Inventor. The paper&#;which Yoshino had sent for but hadn&#;t gotten around to reading&#;described a lithium cobalt oxide cathode. Could it work with his plastic anode?

Yoshino, along with a small team of colleagues, paired Goodenough&#;s cathode with the plastic anode. They also tried pairing the cathode with a variety of other anode materials, mostly made from different types of carbons. Eventually, he and his colleagues settled on a carbon-based anode made from petroleum coke.

Yoshino&#;s battery, developed at Asahi Chemical in the late s, combined Goodenough&#;s cathode with a petroleum coke anode. Johan Jarnestad/The Royal Swedish Academy of Sciences

This choice of petroleum coke turned out to be a major step forward. Whittingham and Goodenough had used anodes made from metallic lithium, which was volatile and even dangerous. By switching to carbon, Yoshino and his colleagues had created a battery that was far safer.

Still, there were problems. For one, Asahi Chemical was a chemical company, not a battery maker. No one at Asahi Chemical knew how to build production batteries at commercial scale, nor did the company own the coating or winding equipment needed to manufacture batteries. The researchers had simply built a crude lab prototype.

Enter Isao Kuribayashi, an Asahi Chemical research executive who had been part of the team that created the battery. In his book, A Nameless Battery with Untold Stories, Kuribayashi recounted how he and a colleague sought out consultants in the United States who could help with the battery&#;s manufacturing. One consultant recommended Battery Engineering, a tiny firm based in a converted truck garage in the Hyde Park area of Boston. The company was run by a small band of Ph.D. scientists who were experts in the construction of unusual batteries. They had built batteries for a host of uses, including fighter jets, missile silos, and downhole drilling rigs.

Nikola Marincic, working at Battery Engineering in Boston, transformed Asahi Chemical&#;s crude prototype [below] into preproduction cells. Lidija Ortloff

So Kuribayashi and his colleague flew to Boston in June of , showing up at Battery Engineering unannounced with three jars of slurry&#;one containing the cathode, one the anode, and the third the electrolyte. They asked company cofounder Nikola Marincic to turn the slurries into cylindrical cells, like the kind someone might buy for a flashlight.

&#;They said, &#;If you want to build the batteries, then don&#;t ask any more questions,&#;&#; Marincic told me in a interview. &#;They didn&#;t tell me who sent them, and I didn&#;t want to ask.&#;

Kuribayashi and his colleague further stipulated that Marincic tell no one about their battery. Even Marincic&#;s employees didn&#;t know until that they had participated in the construction of the world&#;s first preproduction lithium-ion cells.

Marincic charged $30,000 ($83,000 in today&#;s dollars) to build a batch of the batteries. Two weeks later, Kuribayashi and his colleague departed for Japan with a box of 200 C-size cells.

Even with working batteries in hand, however, Kuribayashi still met resistance from Asahi Chemical&#;s directors, who continued to fear moving into an unknown business.

Sony gets pulled into the game

Kuribayashi wasn&#;t ready to give up. On 21 January , he visited Sony&#;s camcorder division to make a presentation about Asahi Chemical&#;s new battery. He took one of the C cells and rolled it across the conference room table to his hosts.

Kuribayashi didn&#;t give many more details in his book, simply writing that by visiting Sony, he hoped to &#;confirm the battery technology.&#;

Sony, however, did more than &#;confirm&#; it. By this time, Sony was considering developing its own rechargeable lithium battery, according to its corporate history. When company executives saw Asahi&#;s cell, they recognized its enormous value. Because Sony was both a consumer electronics manufacturer and a battery manufacturer, its management team understood the battery from both a customer&#;s and a supplier&#;s perspective.

And the timing was perfect. Sony engineers were working on a new camcorder, later to be known as the Handycam, and that product dearly needed a smaller, lighter battery. To them, the battery that Kuribayashi presented seemed like a gift from the heavens.

John Goodenough and his coinventor, Koichi Mizushima, convinced the Atomic Energy Research Establishment to fund the cost of patenting their lithium cobalt oxide battery but had to sign away their financial rights to do so. U.S. PATENT AND TRADEMARK OFFICE

Several meetings followed. Some Sony scientists were allowed inside Asahi&#;s labs, and vice versa, according to Kuribayashi. Ultimately, Sony proposed a partnership. Asahi Chemical declined.

Here, the story of the lithium-ion battery&#;s journey to commercialization gets hazy. Sony researchers continued to work on developing rechargeable lithium batteries, using a chemistry that Sony&#;s corporate history would later claim was created in house. But Sony&#;s battery used the same essential chemistry as Asahi Chemical&#;s. The cathode was lithium cobalt oxide; the anode was petroleum coke; the liquid electrolyte contained lithium ions.

What is clear is that for the next two years, from to , Sony engineers did the hard work of transforming a crude prototype into a product. Led by battery engineer Yoshio Nishi, Sony&#;s team worked with suppliers to develop binders, electrolytes, separators, and additives. They developed in-house processes for heat-treating the anode and for making cathode powder in large volumes. They deserve credit for creating a true commercial product.

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Only one step remained. In , one of Sony&#;s executives called the Atomic Energy Research Establishment in Harwell, England. The executive asked about one of the lab&#;s patents that had been gathering dust for eight years&#;Goodenough&#;s cathode. He said Sony was interested in licensing the technology.

Scientists and executives at the Harwell lab scratched their heads. They couldn&#;t imagine why anyone would be interested in the patent &#;Electrochemical Cell with New Fast Ion Conductors.&#;

&#;It was not clear what the market was going to be, or how big it would be,&#; Bill Macklin, an AERE scientist at the time, told me. A few of the older scientists even wondered aloud whether it was appropriate for an atomic lab in England to share secrets with a company in Japan, a former World War II adversary. Eventually, though, a deal was struck.

Sony takes it across the finish line

Sony introduced the battery in , giving it the now-familiar moniker &#; lithium-ion.&#; It quickly began to make its way into camcorders, then cellphones.

By that time, 19 years had passed since Whittingham&#;s invention. Multiple entities had had the opportunity to take this technology all the way&#;and had dismissed it.

First, there was Exxon, whose executives couldn&#;t have dreamed that lithium-ion batteries would end up enabling electric vehicles to compete with oil in a big way. Some observers would later contend that, by abandoning the technology, Exxon had conspired to suppress a challenger to oil. But Exxon licensed the technology to three other companies, and none of those succeeded with it, either.

Then there was the University of Oxford, which had refused to pay for a patent.

Finally, there was Asahi Chemical, whose executives struggled with the decision of whether to enter the battery market. (Asahi finally got into the game in , teaming up with Toshiba to make lithium-ion batteries.)

Sony and AERE, the entities that gained the most financially from the battery, both benefitted from luck. The Atomic Energy Research Establishment paid only legal fees for what turned out to be a valuable patent and later had to be reminded that it even owned the patent. AERE&#;s profits from its patent are unknown, but most observers agree that it reaped at least $50 million, and possibly more than $100 million, before the patent expired.

Sony, meanwhile, had received that fortuitous visit from Asahi Chemical&#;s Kuribayashi, which set the company on the path toward commercialization. Sony sold tens of millions of cells and then sublicensed the AERE patent to more than two dozen other Asian battery manufacturers, which made billions more. (In , Sony sold its battery business to Murata Manufacturing for 17.5 billion yen, roughly $126 million today).

None of the original investigators&#;Whittingham, Goodenough, and Yoshino&#;received a cut of these profits. All three, however, shared the Nobel Prize in Chemistry. Sony&#;s Yoshio Nishi, by then retired, wasn&#;t included in the Nobel, a decision he criticized at a press conference, according to the Mainichi Shimbun newspaper.

In retrospect, lithium-ion&#;s early history now looks like a tale of two worlds. There was a scientific world and a business world, and they seldom overlapped. Chemists, physicists, and materials scientists worked quietly, sharing their triumphs in technical publications and on overhead projectors at conferences. The commercial world, meanwhile, did not look to university scientists for breakthroughs, and failed to spot the potential of this new battery chemistry, even those advances made by their own researchers.

Had it not been for Sony, the rechargeable lithium battery might have languished for many more years. Almost certainly, the company succeeded because its particular circumstances prepared it to understand and appreciate Kuribayashi&#;s prototype. Sony was already in the battery business, it needed a better battery for its new camcorder, and it had been toying with the development of its own rechargeable lithium battery. Sony engineers and managers knew exactly where this puzzle piece could go, recognizing what so many others had overlooked. As Louis Pasteur had famously stated more than a century earlier, &#;Chance favors the prepared mind.&#;

The story of the lithium-ion battery shows that Pasteur was right.

This article appears in the August print issue as &#;The Lithium-ion Battery&#;s Long and Winding Road.&#;

Abstract

Lithium batteries are electrochemical devices that are widely used as power sources. This history of their development focuses on the original development of lithium-ion batteries. In particular, we highlight the contributions of Professor Michel Armand related to the electrodes and electrolytes for lithium-ion batteries.

Keywords: intercalation compounds, lithium batteries, electrolyte, cathode, anode

1. Introduction

Lithium &#;lithion/lithina&#; was discovered in by Arfwedson [1] and Berzelius [2] by analyzing petalite ore (LiAlSi4O10), but the element was isolated through the electrolysis of a lithium oxide by Brande and Davy in [3]. It was only a century later that Lewis [4] began exploring its electrochemical properties. Considering lithium&#;s excellent physical properties, such as its low density (0.534 g cm&#;3), high specific capacity ( mAh g&#;1), and low redox potential (&#;3.04 V vs. SHE), it was quickly realized that lithium could serve well as a battery anode.

In early , Harris [5] examined the solubility of lithium in various non-aqueous (aprotic) electrolytes&#;including cyclic esters (carbonates, γ-butyrolactone, and γ-valerolactone), molten salts, and inorganic lithium salt (LiClO4)&#;dissolved in propylene carbonate (PC). He observed the formation of a passivation layer that was capable of preventing a direct chemical reaction between lithium and the electrolyte while still allowing for ionic transport across it, which led to studies on the stability of lithium-ion batteries [5,6]. These studies also increased interest in the commercialization of primary lithium-ion batteries.

Since the late s, non-aqueous 3 V lithium-ion primary batteries have been available in the market with cathodes including lithium sulfur dioxide Li//SO2 in [7]; lithium&#;polycarbon monofluoride (Li//(CFx)n commercialized by Matsushita in ; lithium&#;manganese oxide (Li//MnO2) batteries commercialized by Sanyo company in , initially sold in solar rechargeable calculators (Sanyo, Lithium Battery Calculator, Model CS-L); lithium&#;copper oxide (Li//CuO) batteries still used today [8]; and (Li/LiI/Li2PVP) batteries with an Li metal anode, a lithium iodine electrolyte, and a polyphase cathode of polyvinyl-pyridine (PVP) used in cardiac pacemakers since (see Holmes [9] for the history of this primary battery). Simultaneously, advances in the understanding of the intercalation of lithium in different materials gave birth to rechargeable (secondary) lithium-ion batteries. In this review, we report a brief history of these secondary batteries that have now taken an important place in our daily life, as we find them in many devices ranging from portable phones to electric vehicles. Attention is focused on the beginning of their development in the period of &#;. The contribution of Michel Armand is highlighted in this context.

2. Intercalation Cathode Development

In the early s, research was rekindled in the area of the intercalation reactions of an ion, atom, or molecule into a crystal lattice of a host material without destroying the crystal structure. The following general criteria are needed for reversible intercalation reactions: (a) the materials must be crystalline; (b) there must be empty sites in the host crystal lattice in the form of isolated vacancies or as one-dimensional (1D) channels, 2D layers (van der Waals gap), or channels in a 3D network; and (c) both electronic and ionic conductivity must be present for reversible Li intercalation&#;deintercalation [10,11]. Based on these criteria, pioneering intercalation studies on Prussian-blue materials, such as iron cyanide bronzes M0.5Fe(CN)3, were demonstrated by Armand et al. [12] in . The same year, the topic of energy storage devices and the concept of solid-solution electrodes and electrolyte components for lithium-based secondary batteries were discussed at a NATO conference in Italy, where Brian Steele suggested the use of transition metal disulfides as intercalation electrode materials [13]. Other groups, notably Gamble et al. [14] and Dines et al. [15,16] (EXXON, USA), evaluated transition-metal chalcogenide (MS2, with M = Ta, Nb, and Ti) electrode materials. At the same conference, Armand suggested the use of several inorganic materials and transition metal oxides, reported the use of CrO3 within graphitic planes as an electrode material for both Li and Na batteries, and described the first solid-state battery using β-alumina as a solid electrolyte [17].

In , inspired by the pioneering work of Rao et al. [18] (IBM, USA) and the group of Rouxel [19] (Nantes, France) who demonstrated the fast kinetics of the intercalation reactions in metal disulfides, Whittingham patented the Li//TiS2 battery [20,21], and the electrochemical properties of Li0//TiS2 battery were simultaneously investigated by Whittingham [22] and Winn et al. [23,24] in . One decade later, Li//TiS2 cells were commercialized under the form of standard-sized XR coin cells by Eveready Battery Co., USA for CMOS memory back-up applications [25,26], under an AA-sized form by Grace Co., USA with a capacity of 1 Ah [27] and under a C-sized form for a cell operating at temperature in the range of &#;20 to +20 °C with a capacity of 1.6 Ah [28]. Another metal disulfide, namely MoS2, also met success: Li0//MoS2 cells (MOLICELTM) were manufactured by Moli Energy Ltd. in Canada, with an energy density of 60&#;65 Wh kg&#;1 at a discharge rate of C/3 (800 mA) [29]. Among other metal chalcogenides investigated at that time, only NbSe3 emerged. Following the study of this material as a cathode element by Murphy et al. [30] in , AT&T (USA) commercialized an AA-sized Li0//NbSe3 cylindrical cell operating over 200 cycles at a current of 400 mA with a capacity of 0.7 Ah in [31]. For completeness, we mention V2O5, which was also used as a cathode element of commercialized lithium-ion batteries, but this was only done in the s. Since the present review focuses on the early development of lithium batteries, we guide the reader to a book for further details concerning them [32].

Inspired by the studies on NaxCoO2 by the group of Hagenmuller [33] in , Goodenough et al. [34] replaced Na with Li and proposed LiCoO2 as a new cathode (3.9 V vs. Li+/Li) that they patented in . LiCoO2 is more stable in air than NaCoO2, and its good electrochemical properties [35] have earned it the most commercialized cathode for decades. This result opened up a new approach for research into the development of solid-solution materials, in particular Li(NixMnyCoz)O2 (NMC) in the s, as reviewed elsewhere [32].

Early work on spinel LiMn2O4 was carried out in by Thackeray et al. [36]. Mn is low cost compared to Co, and the thermal stability of LiMn2O4 is better than that of LiCoO2. The problem of Mn&#;s dissolution into electrolytes at high temperature, however, was not solved until Zhou et al. found an effective salt, LiFNFSI, which improves resilience [37].

Further advances were made in the development of olivine-based cathodes, and in particular LiFePO4, which was pioneered by the Goodenough&#;s group [38]. The watershed for the use of these materials was the discovery of a carbon-coating process discovered in an international lab (France-Québec) directed by Armand (see Ref. [39] and references therein).

LiFePO4 has a remarkable thermal stability, but its redox potential (3.5 V vs. Li+/Li) is small. LiCoO2 has a rather poor stability, but it belongs to the class of 4 V cathodes. Therefore, in parallel to the development of the LiFePO4 battery, further research was done to improve the thermal stability of LiCoO2 by the synthesis of solid solutions involving doping by Ni, Mn, and non-transition elements. Early work in by the group of Delmas et al. [40] suggested a solid-solution concept that was then explored by many groups to optimize the Li(NixMnyCoz)O2 (NMC) cathode that is now commercialized by various companies due to its high energy density; it now shares the market with LiFePO4.

3. Development of Anode Materials

In addition to the development of positive (cathode) electrode materials, research was also carried out on Li-metal and Li-alloy negative (anode) electrodes. Early batteries were commercialized with such anodes [25,26,27,28,29,30,31]. However, they faced safety concerns due to the formation of anode dendrites.

The insertion of lithium in graphite dates from , but this was only confirmed by the synthesis of LiC6 in [41]. The synthesis of LiC6, however, was not obtained by electrochemical process at that time, and the reversible intercalation of lithium in graphite up to LiC6 was established by Besenhard and Eichinger in [42,43], but, owing to a lack of a suitable electrolyte that could prevent co-intercalation at that time, graphite was not used as a cathode material. This problem was solved by the group of Armand in by the use of polymer electrolyte that allowed these authors to identify the suitability of graphite as an intercalated negative electrode [44,45].

In the s, Armand proposed the fabrication of a lithium-ion battery based on two different intercalation materials for both cathodes and anodes; this battery was named the rocking-chair battery (later the lithium-ion battery) due to the shuttle of ions from one electrode to another during the charge&#;discharge process [46]. This concept involved lithium ions being transferred from one side to the other [45] and was demonstrated in by Lazzari and Scrosati [47].

The rocking-chair battery concept was thus offered the same year as the LiCoO2 positive electrode was proposed by Goodenough, but the laboratory experiment has to be taken to the industrial scale. This was achieved by the commercialization of the LiCoO2//hard-carbon battery by the Sony and Asahi Kasei teams led by Nishi in . The rocking-chair concept later gained major success in the Japanese battery industry with Sony [48] () and Sanyo in [49].

In the s, another anode material, the spinel Li4Ti5O12, was proposed for Li-ion batteries [50,51] and, more recently, for Na-ion batteries [52]. This anode may substitute graphite only when high-power density is needed, but in Na-ion batteries, the Li4Ti5O12 electrode delivers a reversible capacity of 155&#;mAh&#;g&#;1 and presents the best cycle ability among all reported oxide-based anode materials [53].

4. Electrolytes

Armand was a pioneer in the development of a polymer electrolytes based on polyethylene oxide-lithium salts (PEO:Li) [54,55]. Solid-state batteries have the advantage that they use Li as the anode the collector current. As a result, the theoretical energy density of solid-state batteries is larger than that of Li-ion batteries that use liquid electrolytes. The drawback is that the PEO and polymers in general have a poor ionic conductivity at room temperature, so that the commercial all-solid-state lithium-ion batteries that use polymers, such as the batteries in Bluecars® and Bluebuses®, must be used at elevated temperatures. On another hand, liquid electrolytes are very good ionic conductors, and it is difficult to avoid the formation of dendrites at the surface of lithium metal. As a consequence, liquid electrolytes have been adopted in commercial batteries. Such is the case, for instance, for the above-mentioned LiCoO2 battery of Sony that used LiPF6 in propylene carbonate and diethyl carbonate (PC:DEC, 1:1) as the electrolyte. However, PC and DEC are not compatible with lithium metal, so Li-ion batteries with liquid electrolytes adopt the rocking-chair concept with graphite anodes proposed by Armand, implying a smaller theoretical energy density but a higher rate capability at room temperature than all-solid-state batteries. The use of graphite, however, implies that PC was commonly used in the first batteries, as its intercalation results in exfoliation of the carbon sheets. Indeed, the Sony LiCoO2-type battery used hard carbon as the anode. The long cycle life of Li-ion batteries with graphitic carbon and liquid electrolytes (without PC) was demonstrated by Basu [56] in , who used a two-molar solution of LiAsF6 dissolved in 1,3 dioxolane. Only in the s, however, did commercialized batteries emerge with a graphite anode using a liquid electrolyte with LiPF6 in carbonate solvents; this is still the standard today.

In , the group of Armand reported a novel salt: lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) [57], now commonly used as an Li-ion conducting electrolytes for Li-ion batteries and later on a new class of single-ion solid polymer [58,59] and solvent-in-salt electrolytes [60], which gives more evidence that Armand was one of the researchers that played a major role in the development of lithium-ion batteries in the period of time covered in this review. Actually, the period of time where he played a major role is continuing. Further details, including the more recent contributions of Armand to the field of electrolytes, were discussed in a recent review [46], but his recent contributions include advanced materials in all components, including electrodes, of lithium- and sodium-ion batteries [61,62].

Prior patents that paved the route to the present Li-ion batteries are reported in Table 1, and the increase of the energy density of the batteries through the early years of rechargeable batteries is illustrated in Table 2. Note, however, that this figure can only give a partial view of the progress since energy density is not the only parameter that is meaningful. For instance, a battery with an LiFePO4 cathode and a Li4Ti5O12 anode can be cycled over 30,000 cycles at very fast rate of 15C (4 min) and a discharge rate of 5C (12 min) [63]. This performance gives interest to such a battery for some applications, even though its energy density is smaller than that of the LiFePO4-graphite battery, since the operating voltage of the battery is reduced by 1.5 V.

Table 1.

List of some of patents related to the early lithium-ion batteries.

Inventor/Company Patent Title Patent Number Application Date Armand, M.; Duclot, M.
(ANVAR, France) See Reference [44] French
7,832,976 22 Nov. Goodenough, J.B.; Mizushima, K.
(UK Atomic Energy Establishment) Fast ion conductors
(AxMyO2) U.S.
4,357,215A 5 April Goodenough, J.B.; Mizushima, K.
(UK Atomic Energy Establishment) Electrochemical cell with new fast ion conductors U.S.
4,302,518 31 March Basu, S. (Bell Labs Inc., USA) Graphite/Li in molten salt U.S.
4,304,825 21 Nov. Armand, M.; Duclot, M.
(ANVAR, France) See Reference [43] U.S.
4,303,748 12 Jan. Ikeda, H.; Narukawa, K.; Nakashima, H. (Sanyo Co., Japan) Graphite/Li in nonaqueous solvents Japanese
1,769,661 18 June Basu S. (Bell Labs Inc., USA) Graphite/Li in nonaqueous solvents U.S.
4,423,125A 13 Sept. Yoshino, A.; Jitsuchika, K.; Nakajima, T.
(Asahi Chemical Ind., Japan) Li-ion battery based on carbonaceous material Japanese
1,989,293 5 Oct. Nishi N., Azuma H., Omaru A.
(Sony Corporation) Non aqueous electrolyte cell U.S.
4,959,281 29 Aug. Fujimoto, M.; Yoshinaga, N.; Ueno, K. (Japan) Li-ion secondary batteries Japanese
3,229,635 Nov. Open in a new tab

Table 2.

Table of the main early rechargeable lithium batteries that were commercialized before . Note that they all have a lithium metal anode, with the first lithium-ion battery with a carbon anode dating to and the rocking chair concept (Michel Armand) dating to .

Electrochemical
System Voltage
(V) Specific Energy Commercial Co. (Issue) Wh/kg Wh/L Li//TiS2 2.1 130 280 Exxon () Li//LiAlCl4-SO2 3.2 63 208 Duracell () Li//NbSe3 2.0 95 250 Bell Lab. Inc. () LiAl//polyaniline 3.0 - 180 Bridgestone () Li//MoS2 1.8 52 140 MoLi Energy () Li//V2O5 1.5 10 40 Toshiba () LiAl//polypyrolle 3.0 - 180 Kanebo () Li//Li0.3MnO2 3.0 50 140 Tadiran () LiVOx 3.2 200 300 Hydro-Québec () C//LiCoO2 3.6 150&#;190 - Sony () Open in a new tab

The stability of different electrolytes and the Li-polymer cell architecture proposed by Professor Michel Armand are illustrated in Figure 1. The sequence of stability ranges in the order cyclic carbonates (SEI zone) < polyethylene oxide (PEO) < molten salts.

Figure 1.

Open in a new tab

(a) Stability of different electrolytes and (b) solid state lithium metal polymer battery architecture proposed by Professor Michel Armand.

5. Separators

For completeness, we mention the separator, which is the last important component of lithium-ion batteries. This element, however, has raised much less trouble than electrodes and electrolytes. As soon as , a time where lithium metal was used as the anode of primary batteries with organic electrolytes, prototype models of Li//CuS cells had been developed by SAFT in France in a pilot line type of operation [64,65,66], using a non-woven polypropylene separator. The Li//V2O5 system patented by Livingston Electronic Corporation (now Honeywell) [6] and P. R. Mallory and Co. Inc. [67,68] used a cellulosic separator, e.g., filter paper or a Celgard® separator of porous polypropylene. Another example is the Li//SO2 system [69]. Actually, most of the lithium metal batteries developed in the early s already used a non-woven polypropylene separator. The alternative was a glass-fiber paper separator, like in the case of the Li//SOCl2 cell [70].

6. Conclusions

Fundamental works on lithium-ion batteries date from the s, and remarkable progress has been made since the s. The first commercial lithium-ion battery was issued in , making it a rather short period of time between work in laboratories and the industrial production. In this review, we reported the main steps that led to this success. Among the people that contributed to this success from this beginning up to now, Michel Armand has played a key role in the creation and development of lithium-ion battery cathodes, anodes, and electrolytes. We deem him to be one of the &#;forefathers of modern batteries,&#; inspiring many academic and industrial researchers to design alternative electrode and electrolyte materials with high energy densities, long cycle lives, and low costs, leading to the further development of the batteries for electric vehicles and for the regulation of the current produced by intermittent sources before integration into smart grids.

Acknowledgments

The authors thank John B. Goodenough for helpful comments.

Author Contributions

Conceptualization, K.Z.; writing&#;original draft preparation, M.V.R. and A.P.; writing&#;review and editing, A.M. and C.M.J. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Conflicts of Interest

The authors declare no conflict of interest.