By Jenny Lee WIRED Korea
Everyone knows at this point that the future of mobility is electric. The adoption of electric vehicles (EVs) is already happening and at a much faster pace than anyone predicted. But the EV uptake is expected to be further accelerated in the years to come, to the point where its sales will surpass those of internal combustion models.
What is critical to this is the availability of a new type of battery that is safe and can last a long time.
How Batteries Work
A battery is a device that converts chemical energy directly into electrical energy by a process that involves the transfer of electrons from one electrode to another through an external circuit. To balance the movement of electrons, charged ions also move via an electrolyte solution, a conductive medium that is in contact with both electrodes.
Its history dates back as far as 1800, when Italian physicist Alessandro Volta invented the world’s first battery by stacking discs of copper and zinc separated by a cloth soaked in salty water. The battery has evolved steadily ever since.
The most widely used battery is the lithium-ion (Li-ion) battery, which operates by sending lithium ions from the positive electrode to the negative electrode during charge and vice versa during discharge. Installed in a wide range of electronic devices and EVs, this battery is lightweight, has a high energy density and can be recharged and reused thousands of times.
One drawback, however, is that the liquid electrolyte in it is highly volatile and can lead to battery fires or explosions, such as those that have plagued the Tesla electric car, the Boeing 787 Dreamliner and Samsung Note 7 smartphone.
“Liquid electrolytes can trigger battery fires when foreign substances, for example, get caught between the electrodes, or if a short circuit occurs for any reason, it generates immense heat and can result in an explosion,” says Hong Seung-bum, an associate professor at the Korea Advanced Institute of Science and Technology’s Department of Materials Science and Engineering. “As long as an organic liquid electrolyte is used, there is always a risk of fire.”
Big Challenge Remains
In view of serious threats posed by the current battery architecture to human life and health, applying it to EVs may not be so ideal. As a result, researchers around the globe are looking to replace the liquid electrolyte with a solid material to overcome this limitation.
“The development of all-solid-state batteries has been underway for more than 10 years,” Hong says. “With the electrolyte having a solid form, these batteries contain no volatile components and therefore is much safer."
The biggest hurdle at present, he says, is that very few, if any, solid-state electrolytes have ion conductivity as high as liquid organic electrolytes. Because Li-ions travel slowly between electrodes in the solid-state electrolyte, these batteries’ charge and discharge capacities are not yet competitive enough to be commercialized.
So, making solid electrolyte materials, in which Li-ions can move as fast as they do in liquid electrolytes, is key, Hong says.
The Race for Solid-State Batteries Heats Up
In 2010, Japan's Toyota published a paper in which it said it had succeeded in developing a prototype of an all-solid-state battery that used graphite and lithium compounds as electrodes and sulfur compounds as an electrolyte. It claimed the battery had a very high power density and could be used in electric cars, as a complete charge or discharge of the battery could be done in just seven minutes – the amount of time needed to have an empty car to become fully charged. It said it could also operate at minus 30 up to 100 degrees Celsius.
Korean battery manufacturers such as Samsung SDI, SK Innovation and LG Chem, are also bent on developing all-solid-state batteries. Samsung, in particular, said in early March that its researchers have developed a battery technology that would enable an EV to drive up to 800 kilometers on a single charge with a life cycle of over 1,000 charges.
Having invested into a couple of U.S.-based solid-state battery developing firms, Korea’s auto giant, Hyundai Motor Group, is also weighing up plans to develop its own such battery, according to news reports.
No prototype has yet been constructed by Korean battery makers, which suggests these batteries are not expected to be seen in the near future. The global all-solid-state battery market is projected to reach 38 trillion won ($22.8 billion) by 2035, according to the Fuji Economic Institute in Japan.
“These batteries are at least three to five years away from commercialization,” Hong says.
저작권자 © WIRED Korea 무단전재 및 재배포 금지
이 기사를 공유합니다