Recently, Chinese electric vehicle manufacturer BYD announced it has developed a new ultra-fast charging technology, surprising the global market. The global battery industry is highly interested in how BYD has overcome the limits of performance and expense, but BYD has not provided a clear explanation on this.

Wang Chuanfu, chairman of BYD, stated at a technology presentation held at the company's headquarters in Shenzhen, China, on the 17th, "We have developed a 'super e-platform' that can drive 400 kilometers after a 5-minute charge." This significantly surpasses the battery charging technologies of global competitors. The Supercharger system from American electric vehicle maker Tesla allows for a 15-minute charge to drive 320 kilometers. Mercedes-Benz recently unveiled an electric model of the CLA sedan that can drive 325 kilometers with a 10-minute charge.

News that BYD has developed technology that could be a game changer in the global electric vehicle market led to a 5.3% drop in Tesla's stock on the New York Stock Exchange on the 18th (local time). However, domestic academia and the battery sector express skepticism about whether the technology released by BYD can meet both performance and expense criteria.

Wang Chuanfu, Chairman of BYD, explains the new charging technology at the company's headquarters in Shenzhen, China, on Nov. 17. /Courtesy of BYD

◇ "5-minute charge and 400km range" theoretically possible, but energy density and expense are issues.

Choi Nam-soon, a professor of biochemical engineering at the Korea Advanced Institute of Science and Technology (KAIST), noted in a phone interview with ChosunBiz, "Completing a charge in 5 minutes is theoretically quite possible, but the discharge is fast, and the burden of expense will only increase. BYD has not explained how it plans to solve these issues at all."

Professor Choi explained that using graphite, which is mainly used as the anode material in secondary batteries, makes it very difficult to charge within 5 minutes. To shorten the charging time with graphite anodes, it is necessary to make the plates very thin and use a lot of separators, which in turn increases the weight of the battery and reduces fuel efficiency.

Additionally, the copper used as a separator is expensive. Increasing the amount of separators to facilitate fast charging and extend the driving range will inevitably raise battery manufacturing expenses.

Professor Choi commented, "If all aspects including energy density and expense were disclosed in addition to the 5-minute charge and 400-kilometer range, it could be considered a true innovation, but it was disappointing there was no such explanation. Developing a 5-minute charging battery that meets both energy density and low expense is impossible."

Kim Dong-myung, president of LG Energy Solution, South Korea's top battery manufacturer, also expressed similar views during a shareholders' meeting on the 20th. He said, "The technology for charging in 5 minutes is theoretically possible. Not just LG Energy Solution but anyone can do it," while emphasizing, "How you structure the cost is a significant issue." He added, "However, BYD is a company that manufactures both batteries and vehicles, so optimizing costs could be easier for them."

On Jan. 16, at the 'BYD Passenger Car Brand Launch Media Showcase' held at the Song Sang Platform in Jung-gu, Incheon, Jo In-cheol (left), representative of BYD Korea's passenger division, and other officials are taking a commemorative photo. /Courtesy of BYD

◇ Concerns about shortened battery lifespan and fire risks.

Kwon Hyo-jae, CEO of COR Energy Insights, pointed out several aspects to consider regarding BYD's new charging technology. He is an energy expert with over 20 years of experience at Hanwha Ocean and American energy corporations.

BYD revealed at the technology presentation that it has developed batteries with a 10C-rate charging speed, motors producing over 500 horsepower, and SiC (silicon carbide) power semiconductor chips supplying stable power of over 1000V. The C-rate indicates the charging speed of the battery; the number before C denotes how long it takes to fully charge a 60-kilowatt-hour (kWh) battery. For example, 10C means it takes 6 minutes to charge a 60 kWh battery.

Kwon stated, "When combining 10C charging, high-performance motors, and high-performance power semiconductors, the performance of electric vehicles can reach supercar levels," and added, "The key issue is the battery's lifespan." He noted, "If the battery can guarantee a lifespan of over 2000 charges even with frequent 10C charging, it could be a game changer, but if the battery's lifespan declines rapidly, then fire issues may arise."

He also expressed concerns about the durability of SiC power semiconductors. He mentioned, "SiC power semiconductors with over 1000V have already been introduced in energy storage systems (ESS), but there are many opinions about short-circuiting issues, and their reliability still seems insufficient."

Kwon said, "I was curious about how BYD solved such limitations, but there was no explanation regarding this at the technology presentation," and analyzed, "Currently, the electric vehicle market is witnessing intensified competition, and very few companies are making money compared to their investments. The fact that the chairman of BYD has decided to take a substantial risk technically by promoting '5-minute charging and 400 kilometers of driving' likely stems from this background."