Panasonic, Toyota and other companies have applied for more than a third of international patents in the field of batteries.
The number of Japan’s applications for international patents related to batteries in 2018 was 2,339.
South Korea ranked second, according to the joint study By measuring patent applications filed in two or more countries.
The East Asian economy is in a fierce race to dominate batteries, which are essential to the widespread use of electric cars and renewable energy.
China ranked fourth in patent filings, followed by the United States in fifth place, according to the study, while the 38 contracting countries to the European Patent Convention ranked third.
Japanese companies made up 7 out of the top 10 patent filing companies from 2000 to 2018.
Samsung was the South Korean company that produced the most, with 4,787 inventions Panasonic ranked second with 4,046, followed by LG with 2,999.
Battery innovation took off in the past two decades, and international patent applications for as many as 7,153 inventions related to electricity storage were published in 2018, a sharp increase compared to the number 1029 published in 2000.
Innovations involving lithium-ion cells, used in cell phones and laptops, accounted for 45 percent of battery cell patenting activity in 2018.
Improved battery cells allow electric cars to travel farther on a single charge, and storage technology also enables the reliable supply of energy needed to compensate for fluctuations in solar and wind power generation.
And while Japan leads patent applications for batteries, it is lagging behind in electric cars.
The report notes that Japan’s leadership in battery technology has not yet translated into a major share of the global electric vehicle market.
The study said: China, which has 1.1 million electric cars, accounted for half of the global market in 2019, while Japan represented only 2 percent of the global market in 2019.