Twenty seven years ago, the lithium ion batteries came to the global market as a result of creative work by Asahi Kasei, Yoshino and development by the Sony Corporation. The creation of lithium ion batteries came about rapidly and has continued to display remarkable progress in capacity, energy, power and cost reduction. With recent progress in new materials, lithium ion batteries are presumed to continue to improving in all of its properties with new battery concepts in active materials, inert materials and cell designs. Initially, I wanted to look into the future of lithium ion batteries and where they are going (TESLA TESLA TESLA) but then I started reading about lithium ion batteries and their story and it’s interesting how a concept can make it’s from an idea’s in someone’s head to a billion systems spread around the world. Of course, this project isn’t the history of all battery cells but a brief look at the steps taken to get from the drawing board to the market.
The beginning of the modern lithium ion battery:
Though Sony was the first primary manufacturer and vendor of lithium ion batteries, there were many previous studies that prelude the one sold in 1991. The concept of a cell in which the lithium ions move reversibly between the Anode and Cathode was first formulated by Armand in the late 1970s, by using intercalation materials of different potentials for the two electrodes, and is often called a rocking chair battery because of the flow of lithium ions back and forward between the two electrodes.1 The idea was picked up by Lazzari and Scrosati soon after and implemented with a lithiated tungsten dioxide electrode and a titanium disulfide electrode4. The potential voltage range was only between 0.8 to 2.1 volts and the electrodes both featured significant molecular weights, but the principle was established. After the cell cycled for over 60 cycles however, the charge voltage required was about 2.2 V and discharge was approximately a low return of 1.6 V.
A discovery by the Goodenough laboratory5 was the ability of NaFeO2 from the lithiated transition metal oxide family. It was able to reversibly deintercalate and reintercalate lithium ions at relatively high potentials. Nickel and cobalt as well as other combinations with Mn, Al, Fe, were all found to have this ability and the later adoption of this patented material (LiCoO2) formed the active positive material of Sony’s lithium ion battery. Quickly after this jump, J. C. Hunter of the Eveready Laboratories6 discovered a new form of MnO2, that could be reversibly reduced and oxidized in a nonaqueous electrolyte at a high potential similar to that of LiCoO2 with a similar capacity. Yay! This material was also later selected for a number of higher rate batteries for commercial applications.
The discovery of suitable negative electrode materials was somewhat more complicated than the positive electrode materials. Early work on graphite and carbonaceous materials had shown that lithium ions can be intercalated. An important finding by Fong, Von Sacken and Dahn, showed that petroleum coke was much better than graphite for resistance to solvent co-intercalation and reduction, while addition of ethylene carbonate to PC greatly improved the resistance on both graphite and petroleum coke. Yoshino and coworkers, from Asahi Kasei (a Japanese battery supplier of separators and electrolytes) used the benefits of lower temperature carbons such as petroleum coke in a seminal patent that resulted in identifying Yoshino as the true inventor of the lithium ion battery.
The reversible capacities of the cokes cycled at low rates which were only half that of the graphite. Yoshino experimented with pure starting materials, rather than petroleum. The purity of the coke was much higher than those used by Dahn’s group. Both parties contributed to the evolution of the ion battery but Yoshino’s model was superior through his more refined and mixtures of specific chemicals salt, binding and electrode combinations. Asahi Kasei later formed a joint venture to create A&T Battery Corp. to make lithium ion batteries.
Ion batteries go corporate
A&T was operating as a subsidiary company within Toshiba. While the main elements of a lithium ion battery were laid out by Yoshino, the battery was nowhere near having a commercial battery with superior properties compared to nickel cadmium and the newly discovered nickel metal hydride batteries. The need was great, because of the deficiencies of these earlier batteries, particularly low specific energy, poor charge retention and environmental problems with the cadmium system.9 Additionally, the electronics industry was rapidly developing, particularly in the sections of computations, communication and cameras. Sony was one of the leading companies in consumer electronics and was willing to bring new inventive products to the table unlike anything else on the market. Sony was a relative newcomer to the battery business, learning the alkaline primary cell technology, but severed that focus and began work in earnest on rechargeable batteries.1
The new generation of Cathodewere introduced; a hard carbon with higher specific capacity was substituted for the coke. A still later development was the now commonly used mesophase carbon microbeads (MCMB). This gave a still higher specific capacity and a flat discharge profile. The positive electrode material, LiCoO2, was carefully designed to have coarser particle size and good crystallinity.
A crash project with Kureha Chemical Ind. Co. developed an improved material giving greatly improved adhesion to the Al carrier foil.7 Sony’s role in producing magnetic tape was helpful in manufacturing the coated electrodes and there is no doubt that part of this experience involved the use of excellent production coating machinery, but, as confirmed by Toru Nagaura,1 one of the key engineers on the project, the particular kind of high energy mixing of the coating slurry was also of great importance. This was also around the time where Nickel coated iron cans were integrated into the system. Nickel coated iron cans were critical to the success of the project because stainless cans originally selected because of the presence of trace amounts of HF, was found to have too high resistance for the applications envisioned.
Sony’s final product
The cell size selected was 18650 (this is based on the naming system for cylindrical lithium primary cells, the first two numbers represent the diameter in mm and the remaining numbers represent the height of the cell in tenths of mm – thus the common a 18650 cell is 18 mm diameter and 65 mm in height) this is the common size for AA batteries. This choice is close to the volume of subC rechargeable nickel based batteries, the most popular size at the time for small electronic devices. The separator selected was a biaxially stretched microporous polyethylene material.5 The electrolyte chosen was ethylene carbonate with a linear dialkyl carbonate and the salt was LiPF6 of high purity and state of dryness.8 The all carbonate solvent had the important property of being highly oxidation resistance. Subsequent improvements in electrolyte have mostly involved the use of additives to improve the film on the negative material, improve the oxidation stability of electrolyte to the positive active material and in some cases reduce the flammability of the electrolyte.
The original Sony product with coke negative had roughly 5 times less energy density than that of what it is today. Allowing for longer lasting battery life, fewer batter recharges, and a refining of the core electrodes, seperators and to get larger numbers of recycles. While Sony remained the industry leader for some time, competition from many other producers finally led to a planned withdrawal of Sony from the battery market, but Sony and Yoshino will forever have left the mark on the world of transportable power that we live in today.