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Sevenfold increase in battery technology patenting at the EPO, but not yet enough to save the planet

Date: 22 October 2020

The European Patent Office (EPO) and the International Energy Agency (IEA) have published a joint study about innovation in batteries and electrical storage. It extends to 100 pages of graphs and data drawn from the database of the EPO. Patent databases provide a wealth of information on trends in technology and the EPO data in particular is supplemented by a series of technology classes that the EPO introduced in 2015, directed to climate change mitigation technologies (CCMTs), allowing the data to be examined in particular for battery technologies that offer the prospect of a more sustainable future. Here we summarize and indeed challenge some of the conclusions of that report.


Aside from a general explosion in investment in battery technology (a 700% increase in published International Patent Families, IPFs, since 2000 as compared with a 213% increase across all technologies) a key observation from the study is a cross-over in applications for battery packs in about 2011. Prior to 2011, the dominant application for battery technologies was portable applications, especially, of course, mobile ‘phones. Since that year, however, automotive applications have exceeded portable device applications, and stationary applications (such as for use in power grid load levelling) have grown steadily. The report notes that vehicle batteries can be modified for stationary use once they have reached the end of their useful lives in vehicles.




The dominant battery technology has been Li-ion, which is described as “mature” and responsible for 45% of patent activity since 2005. Just 7.3% of patenting activity is in other technologies, while 48% is not specific to any particular chemistry.

The report attributes a 90% reduction in battery prices since 2010 primarily to improvements to the composition of Li-ion cathode materials.

The cathode material of a Li-ion battery currently limits its energy density and dominates the battery cost. Different materials have different ions when placed into solution, and corresponding energy levels. Selecting a material that gives a higher difference in energy level between anode and cathode increases the energy density (i.e. the voltage) of the battery. Various cathode materials have been explored over the past decade. More recently, there has been a shift in focus towards improving specific energy, durability, power output, charge/discharge speed and recyclability.


In emerging battery technologies, the report discusses redox flow batteries and supercapacitors. Redox flow batteries tend to be large and heavy. They are suited to stationary applications, because they have highly scalable capacity and very high longevity. Supercapacitors are expensive for the storage capacity they offer, so they have specialist applications (e.g. regenerative braking systems in vehicles and elevators) but they also find application in wind and solar power.




The study emphasises the contribution of innovative Japanese manufacturing companies in the growth of patenting activity in battery technology. Japanese companies were the leaders in patenting through the noughties, but patenting activity from Japan in particular took off in about 2011 to about double that of the nearest rival, Korea. Because the report draws from data spanning almost 2 decades, it lists 13 Japanese manufacturers in its top 25 patent filers. It merely mentions Chinese companies as having “almost caught up with Europe” and making a “similar contribution to the US”.

We suspect the EPO study is skewed towards historical data from the era of portable device batteries. Just because a patent can last 20 years, does not mean we should look at 20 years of data. The average lifespan of a patent in Germany, for example is just 11.3 years.


If we look at all patent filings, we see huge numbers of national filings by Chinese applicants swamping the data for other applicants in other nations. In fact, if all patent applicants are ranked without regard to country of filing, more than half of the top 25 battery manufacturers would be Chinese.


To get a more up-to-date picture of international patent filings, we took a look at the last two years of available data for PCT applicants. This is perhaps not as robust as looking at IPFs (as in the EPO study) but should show companies who have ambitions to expand their patent portfolios beyond their domestic markets. We see LG of S. Korea as a clear leader (clearly LG like to use the PCT system), and we continue to see a preponderance of Japanese companies in the top 25. But we also see four Chinese companies have entered that group, with one (CATL) being in the top 4:






Without doubt, this report shows an increase in patenting activity (and, by implication, investment) in use of battery technologies for vehicles and stationary applications. It does not set out to show that the research into batteries and their applications is about to make a major contribution to a sustainable development target of 10 Gt/year of CO2. The EPO’s CCMT classifications, while useful, do not add much colour to the overall picture. The EPO/EIA report says progress in energy storage technologies is “not on course” to achieve the outcomes of the IEA’s Sustainable Development Scenario.