As the battery industry accelerates toward electrification and energy storage breakthroughs, the European patent landscape is evolving. According to the EPO Patent Index 2024, battery technology filings surged by 24% in 2024 as compared to 2023, driven by demand for electric vehicles and energy storage systems. Solid-state batteries, dry coating processes, and separator technologies are among the most actively patented areas in recent years. However, according to data obtained using our own purpose-built scripts, as well as the EPOs’ new Technical Intelligence Platform, the percentage of battery patents opposed annually remains relatively low (around 1.0%).
The low numbers of oppositions might suggest that battery companies are reluctant to challenge competitors' patents, possibly due to cost, uncertainty, or underestimating risks of broad patents. Yet, recent litigation, including ATL vs. CosMX Power, where German courts issued injunctions over lithium-ion battery patents, and Tulip Innovation’s successful enforcement of separator technology patents against Sunwoda, shows that the sector is not entirely conflict-averse. Do the EPO opposition figures tell the whole story?
An uprising
An interesting trend is emerging in EPO pre-grant third party observations (TPOs). The rate of TPOs filed in the battery sector is low (just 0.61%) and similar to the general uptake of TPOs across all technologies at the EPO. However, over the last 10 years, the number of these pre-grant interventions in the battery space has increased.
The desired result of filing TPOs is generally to achieve a limitation or refusal of the application. For example, they can be used to prevent overly broad or weak patents from being granted, and thus reduce the risk of future litigation or licensing disputes. Actions might therefore be taken relating to technology of commercial relevance or potential infringement risk.
At the EPO, observations may be filed in relation to novelty and/or inventive step, clarity, sufficiency of disclosure and unallowable amendments. The ability to file observations to challenge the clarity of the claims can be particularly useful, as this is not a ground of post-grant opposition. In the battery sector, where the technologies can be relatively mature (e.g. sodium-ion batteries) or competitive and publication-dense (e.g. lithium-ion batteries), innovators may need to rely on parameters, such as particle size, porosity, pore volume, and surface area, in order to distinguish their innovations. The EPO adopts a very strict assessment of the clarity of parameters, and savvy competitors may use this to their advantage in pre-grant TPOs.
The increase in filing of TPOs reflects a growing awareness among competitors of the strategic importance of influencing patent examination outcomes. Companies in the battery sector are monitoring their competitors’ patent activity and ready to act before the application grants.
TPOs may be the early warning system for future disputes.
Another interesting correlation in the data is between the filing of TPOs and subsequent post-grant oppositions. Of the 87,140 applications filed in the H01M sector over the past 10 years, 0.26% have been opposed.
Focusing on granted patents, 10.4% of granted patents with TPOs on the EPO register were later opposed, as compared with only 0.9% of patents without. Patents upon which TPOs have been filed are more than eight times more likely to be opposed.
Take home messages
In a commercially competitive field, TPOs can be used to cost-effectively challenge applications belonging to competitors which may ultimately threaten a product’s route to market. Topics such as clarity, which are not a post-grant ground for opposition, might be a focus of TPOs rather than flagging added matter or patentability concerns that might instead be reserved for oppositions. TPOs can force the limitation of claims, diverting them away from potential areas of interest.
On the other side, patent owners might track TPO activity to identify which applications competitors are watching and anticipate their challenges. Proactively responding to TPOs and reinforcing claims where necessary can strengthen the patent and reduce opposition risk. Frequent TPO filers might be potential adversaries in the market (although, like EPO oppositions, TPOs can be filed anonymously) and can indicate areas of particular commercial importance.
The European battery patent landscape seems to be slowly shifting from quiet filings to more active engagement. TPOs are being strategically filed and can give insight into emerging contentious areas.
Special thanks are due to Chris Casley and Benjamin Oakham for their work in processing and analysing the data sets from the EPO.
