Portal de Periódicos da CAPES

The Age of Li-Ion Batteries

2019; Elsevier BV; Volume: 3; Issue: 11 Linguagem: Inglês

10.1016/j.joule.2019.11.004

2542-4785

Alexandra K. Stephan,

Advanced Battery Technologies Research

On October 9, 2019 the Nobel Prize in Chemistry was awarded to John Goodenough, Stanley Whittingham, and Akira Yoshino for the development of lithium-ion batteries. Alfred Nobel set as a requirement that the Nobel Prize be awarded to work that had benefitted humankind, and although Li-ion batteries have clearly impacted humanity, the battery community had lost hope that this work would be recognized with a Nobel Prize because the pioneering work of Goodenough, Whittingham, and Yoshino was done in the 1970s and 1980s, over 40 years ago. The Nobel laureates’ work was focused on the two main components of batteries, the negative electrode (anode) and the positive electrode (cathode). In the 1970s Whittingham developed an energy-rich cathode material, titanium disulfide. This cathode could intercalate Li ions, which means that the material could uptake Li ions in the spaces in the material without forming chemical bonds between the titanium disulfide and the lithium. He paired this cathode with a Li-metal anode to create a battery with a potential of over 2 V. A larger potential in a battery means that a greater amount of energy can be stored. In an attempt to further increase the potential, Goodenough in the 1980s developed another intercalating cathode made of lithium cobalt oxide, which, when combined with Li metal in a battery, resulted in a potential of 4 V. Finally, in 1985 Yoshino utilized the lithium cobalt oxide cathode developed by Goodenough and coupled it with an intercalating carbon anode made from petroleum coke. When the Sony Corporation in 1991 sold a Li-ion battery based on Yoshino’s design, this became the first commercial Li-ion battery. The performance of the initial Li-ion batteries is remarkable, especially in light of how little was known about Li-ion batteries in comparison to today. In the decades since the first Li-ion batteries, they have become known for the complex processes that occur during charging and discharging and that lead to diminishing performance. During the 1970s and 1980s, the ability to gain fundamental insights into Li-ion batteries was limited by the technology of the time. The advanced in situ and operando characterization tools that have become staples of modern research labs were either not available or not easily accessible during the developmental period of Li-ion battery research. In the time between the conception of Li-ion batteries and today, there has been a monumental amount of research on electrolyte decomposition, solid electrolyte interphase formation, structural changes in anode and cathode materials, etc. These are all significant changes that occur during the repeated cycling of Li-ion batteries and affect performance. The ability to understand these changes has become possible with the advent of advanced characterization tools, and even today there is still not a clear consensus regarding some of these processes. For instance, there is still an ongoing debate with regard to solid electrolyte interphase structure and composition. When the first Li-ion battery entered the commercial market in 1991, these complex processes that occur in Li-ion batteries, even if they were known, were certainly not well understood. Even with limited insight into the electrochemical complexities of Li-ion batteries, Goodenough, Whittingham, and Yoshino designed a Li-ion battery that has stood the test of time. Current commercial Li-ion batteries are exceedingly similar to the battery designed by Yoshino in that they frequently use a lithium cobalt oxide cathode and a carbon-based anode. Though instead of the anode being made of petroleum coke, it is now often graphite. Commercial Li-ion batteries are slowly branching into using other electrode materials such as lithium iron phosphate and lithium nickel manganese cobalt oxide as cathode materials and silicon as an anode material. Even with decades of research and insight, the initial lithium cobalt oxide cathode and carbon-based anode design has proved challenging to surpass. The delay between the development of Li-ion batteries and the awarding of the Nobel Prize this year has provided the time necessary to prove the long-lasting importance and impact of the work. In the context that Li-ion batteries have performed remarkably well even though they were not fully understood when developed and that the original design is still being used decades later, the Nobel laureates’ work becomes nearly miraculous. Additionally, it is unlikely that Goodenough, Whittingham, and Yoshino, when developing their batteries, imagined a future where nearly every person uses a Li-ion battery every day of their lives. Li-ion batteries have undeniably played a crucial role in the prevalence of laptops and cell phones. However, after 40 years the most impressive part of the Li-ion battery story is that the legacy of Li-ion batteries is still yet to be seen. Their development spawned from the energy crisis of the 1970s, and Li-ion batteries have opened the door for the possibility of electric vehicles and electricity grids powered by sustainable energy. As these and other technologies not even imagined yet mature over the coming decades, the impact and legacy of Li-ion batteries and of Goodenough, Whittingham, and Yoshino will continue. While the legacy of Li-ion batteries is still ongoing, the question that we should be asking as a world is what is next for rechargeable batteries? When Whittingham was asked, he responded with “you can expect Li-ion batteries to substantially increase in energy from today’s 200–250 Wh/kg to 350–400 Wh/kg and possibly even to 500 Wh/kg. The latter will need new electrodes and electrolytes. At the same time the safety will improve and the cost will continue to go down.” Interestingly, both Whittingham and Goodenough initially paired their cathodes with Li-metal anodes. The use of Li metal as an anode was eventually deemed too unsafe, which is why carbon-based anodes were ultimately used for commercial batteries. However, in the push to develop batteries with greater energy storage, Li-metal anodes are being revisited. To address the safety issues that plague Li-metal batteries, solid electrolytes instead of traditional liquid electrolytes are being investigated. Also, given the concerns of safety and limited supply of metals, there has been a push to develop alternative chemistries such as Na ion, Ca ion, Zn ion, etc. The challenge that all next-generation batteries face is that Li-ion batteries have successfully dominated the market for nearly 30 years. In order to surpass the Li-ion battery, not only is there a need for outstanding performance and capacity, but perhaps more important is the need for innovation. Maybe the most impactful accomplishment of the Nobel laureates is that they created a new age—an age where editorials can be written on laptops and where vehicles need to be plugged in rather than refueled. This is a time that is defined by what Li-ion batteries have made possible. For some of us, like the author of this editorial, the only age that we have known is this age of Li-ion batteries. As a result, the level of innovation that Goodenough, Whittingham, and Yoshino had to usher in in this age will likely be same level that is necessary to catapult the world into a new era.