THREE DISCOVERIES THAT REVOLUTIONIZED Li+ BATTERIES
For those of you old enough to remember the Sony Walkman portable radios in 1970s, they ushered a new era of consumer electronics, and one could argue, the first mobile battery-powered “devices,” the ancestral precursor to the Apple iPod three decades later. These early electronics were powered by replaceable batteries. Lithium-ion batteries didn’t exist back then. So how did they get invented?A large amount of research and development effort has gone and continues to pour into rechargeable batteries, but one could point to three seminal moments that transformed rechargeable batteries in general, and lithium-ion batteries in particular.
The first moment was in the early 1970s at Exxon. It was a time when large corporations such as GE, Exxon, IBM and others competed with AT&T’s famed Bell Labs for scientific supremacy….a time not much different than ours today with the likes of Google and Apple competing for new innovations. An English-born chemist at Exxon’s research laboratories, Stanley Wittingham, made an important scientific discovery; he found that ions can “intercalate” in between sheets (or layers) of titanium sulfide, and effectively store electrical charge. By shuttling these ions back and forth between two electrodes with such layered materials, he could build a rechargeable battery. Exxon filed for its first battery patent in 1976, and was awarded a US patent 4,084,046 in 1978.
But Exxon and Wittingham ran into several challenges: the batteries degraded fast and they were prone to explode. Exxon couldn’t capitalize on this discovery.
The second seminal moment came from John Goodenough, now professor emeritus at UT Austin, but at the time, he was a professor of Chemistry at Oxford University in the UK. After researching metal oxides and testing several varieties, he and his group discovered that lithium-cobalt-oxide (LCO) was a very effective cathode material. The results were published in 1980: the battery had a higher voltage than Wittingham’s cell (2.2 volts); its energy density was far better than anything on the market; it worked very well at room temperature. It was the missing link to making a rechargeable battery.
Someone had to turn these discoveries into a product; that role was exceptionally fulfilled by Sony in 1991. Sony combined Goodenough’s LCO cathode with a graphite/carbon anode to produce its first commercially available rechargeable lithium-ion battery. Sony put these new batteries into their camcorders and cameras…it was a commercial success. Sony went on to rule lithium-ion batteries for a decade or more. Sony continues to date to be one of the major producers of lithium-ion batteries, albeit several other companies have since emerged as even larger suppliers.
The Sony commercialization was also a major catalyst for laboratories around the world to accelerate the material discovery. John Goodenough’s team at UT Austin went on to discover another category of cathode material, lithium-iron-phosphate (LFP), that was safer than LCO but at the expense of lower energy density.
This post is by no-means intended to give all the inventive credit to the three groups mentioned above. Hundreds if not thousands of innovators and organizations have greatly contributed to the evolution of the lithium-ion battery and continue to do so. Much like the semiconductor industry points to a handful discoveries that transformed electronics, one can trace similar inflection points in the history of the lithium-ion battery.