TOKYO -- Chinese electric-vehicle maker BYD has taken an overwhelming lead in patent filings for EV technology, the arsenal of innovation fueling the company's emergence as a global player.

Nikkei, with the assistance of Tokyo-based analytics firm Intellectual Property Landscape, analyzed EV patent applications from China's four largest sellers of all-electric vehicles. BYD came out in front with 1,557 applications, nearly double the 870 filings of its closest rival, Zhejiang Geely Holding Group.

Chery Automobile was in third place with 640 patent filings, while SAIC Motor took fourth with 448

When it comes to patent applications filed overseas, BYD far outpaces the other three contenders, indicating its strong ambitions for a global expansion.

BYD filed 171 times in Europe, accounting for 11% of all the company's EV patent applications. It submitted 139 applications to the U.S., and 49 to Japan, making for 8.9% and 3.1% of all applications, respectively.

Meanwhile, Geely submitted 58 applications in Europe, or 6.7% of its total. The company filed 33 times in the U.S. and just eight in Japan. Chery applied just a handful of times overseas, while SAIC's applications abroad were next to none.

A battery is about to be installed on a electric car at a BYD assembly line in Shenzhen, China, in May 2016.

BYD was founded in 1995 as a battery manufacturer for electronics. The company entered the automotive business in 2003, and exited gasoline autos in March to focus on EVs and plug-in hybrids.

In China, BYD surpassed Tesla as the largest seller of new energy vehicles in the first half of this year, a category including EVs and other plug-ins.

BYD's patent applications started to grow dramatically in 2016, when it made 203 applications, or 3.5 times the number from the previous year.

In 2016, BYD hired Wolfgang Egger away from Audi to be its chief designer. Since then, BYD's patent application count has tracked an upward trajectory, with the automaker recording 349 filings in 2020.

The other three companies have trailed BYD's activities by at least a few years. Geely's patent applications did not begin to soar until it submitted 98 filings in 2018, or 3.8 times the previous year.

"Right now, BYD is the only Chinese player that can debut in the global market," said Akira Yamauchi, CEO of Intellectual Property Landscape.

Last month, BYD announced it will sell new passenger EV models in a number of European markets, a milestone which marked its transition into a full-fledged operation in that region. The company said it will mount a full-scale entry into the Japanese market next year.

BYD plans to debut three EV models in Japan in 2023. 

It is BYD's emergence as a global EV seller that prompted Nikkei's examination of the company's patents. The study also looked into how much attention it is drawing from other companies.

Toyota Motor has cited BYD patents a total of 103 times in its own patents, the most among any company. That approaches the 146 instances the Japanese automaker has cited Tesla's patents. Meanwhile, Chery only received 29 citations, while SAIC was cited by Toyota in only 9 instances.

"Even in terms of the quality of the patents, BYD dominates Chinese peers," said Yamauchi.

Toyota values BYD's technical prowess to the extent that the two are collaborating. They announced last month that they will soon roll out the bZ3 electric sedan for the Chinese market.

Intellectual Property Landscape ranked patents based on their contribution to the companies' competitiveness, based on how often they are cited and other factors. Those related to BYD's blade batteries, which use phosphates instead of expensive cobalt or nickel, came out on top.

Japanese and South Korean players have an advantage in nickel-manganese-cobalt (NMC) batteries, which have a high energy density and can easily be adjusted for better performance, like a longer range. BYD has focused on developing a thinner, smaller and safe battery, which is being used not only in its electric vehicles slated for sale in Europe and Japan, but also in the bZ3.

BYD also possesses advanced technology on charging and discharging batteries. Of related patents held by the four Chinese players and Tesla, Intellectual Property Landscape ranked five from Tesla and five from BYD among the top 10 most important.

The top spot went to a patent BYD filed in 2013. That technology allows batteries to be charged under different power supply specifications without an expensive converter, and can be used to supply power between EVs or between an EV and an external power grid. It has been cited in at least 100 other related patents filed by Audi, Ford Motor, Hyundai Motor and other companies.

Batteries operate their best at specific temperatures. A patent BYD filed in 2017 involves technology that closely monitors batteries and adjusts their temperature.

Safety has been another priority for BYD. In 2017, it filed a patent for a vehicle design that protects batteries in an accident.

A combined 955,000 EVs, plug-in hybrids and fuel-cell vehicles were sold across 14 major economies in September, according to Tokyo-based research company Marklines. They accounted for 17.8% of overall auto sales, compared with 5% in September 2020.

EV sales are only growing as more countries restrict gasoline-powered vehicles to reduce carbon emissions. BYD could become the world's largest seller of EVs in 2022 after Tesla, which so far has dominated most markets outside China, according to some forecasts.

"BYD could increase its presence on the global stage, armed with technology accumulated from its original operations," said Yamauchi.