Patent attorney Ben Lincoln of Potter Clarkson explains how patent filings in the world of flow batteries provide a barometer for innovation and trends, and identify the key players.
In the rapidly evolving landscape of renewable energy, flow batteries have emerged as a promising solution for large-scale energy storage. As the technology is explored and promising concepts are developed into commercially viable products, protection is sought. Thus, we can start to understand the technological landscape by analysing the patent filings made by the companies researching and developing the technology.
There have been significant developments in flow battery technology over the last 20 years, including the continued refinement of vanadium redox and zinc-bromine technologies and the development of organic redox flow batteries. The identification of high-performance materials in the construction of electrodes and membranes, as well as electrolyte chemistries and additives, drive further patent filings.
More recent advances include the addition of a sugar, β-cyclodextrin, to the electrolyte on the patent database (presently seven patent families on the patent database). Also on the patent database are the exploration of nonaqueous flow batteries (73 patent families listed) and nanoelectrofuels (three patent families).
Patent filings rich landscape
This article looks into the landscape of patent filings in the world of flow batteries, providing a barometer for innovation and exploring trends and identifying key players. Understanding the patent filing and grant statistics can help form a picture of the competitive landscape and the direction of technological advancements in flow battery technology.
The patent databases contain a wealth of technical information. The patent system is provided to encourage innovation and the sharing of knowledge in exchange for a time-limited monopoly. Therefore, understanding what is being filed can provide valuable insight into the research and development performed by competitors.
Having knowledge of the patent landscape may allow for focussing of your own product development to avoid patent infringement or it may prompt collaborations. Once a patent expires or is abandoned, the information it contains can be built on or exploited, subject to relevant checks.
Finding relevant patent documents
One convenient way of finding relevant patent documents is to use the patent classification system. The Cooperative Patent Classification system developed by the European Patent Office and the United States Patent and Trademark Office uses the code H01M8/188 to identify patents and applications that relate to redox flow type batteries.
Therefore, we can start looking at the patent landscape by understanding the number of patent applications filed and the number of those applications that were granted over time (see Graph 1).
Thus, the number of patent applications was relatively flat until 2008, after which there was a surge in patent filing activity. Patent applications take time to be assessed by the relevant patent offices and not all of them progress to become a granted patent. Therefore, there is a delay until the number of patents being granted starts to increase and it can be seen to reach a lower level, as expected.
However, who was responsible for the surge in patent filing activity? Looking at 2008–24, we see that the entities with the greatest number of patent filings are the Dalian Institute of Chemical Physics of China, Sumitomo Electric of Japan and Lotte Chemical Corporation of South Korea. However, it can be easy for large corporations with aggressive patent filing strategies to dominate the statistics.
It is possible to isolate periods of time and look at who the owners are of the patent applications filed in that period. This enables you to see which companies were ahead of the curve on flow battery R&D and who caught on later.
The following three graphs (Graphs 2–4) show the top 10 patent application filers in three different time slices: Jan 2010 – Jan 2012; Jan 2013 – Jan 2015; and Jan 2016 – Jan 2018.
Firstly, it becomes evident that one company was not dominant over the boom years and the component companies of the top 10 changed significantly. While Imergy Power Systems, Inc were the top patent filer in 2010–12, they fell to fifth in 2013–15. Commercial issues led to investors withdrawing support in 2016 and the intellectual property was put up for sale.
VRB Energy held a strong position between 2010 and 2015 and have, according to their website, the GW-Class and MW-Class VRB-ESS flow battery system on offer, where they praise the deep-discharge, long-life and utility-scale advantages of the technology. Further analysis could reveal how their patent portfolio maps to their products.
Redflow R and D PTY made the top 10 in 2010–12 and also offer a zinc-bromide based flow battery product. Enervault Corporation had nine patent families classified as relating to flow batteries in January 2013 to January 2015, after which they fell out of the top 10.
Their filings appear focussed on iron-chromium electrolytes, although several of their patent applications mention the innovations could be applied to other chemistries, such as vanadium. The patent filings in the later years of the 2008–18 period begin to be dominated by the larger corporations, including Sumitomo, LG Chemical, Raytheon Technologies and Lockheed Martin.
Terms appearing in patent applications
In terms of chemistry, we can look at terms that appear in the claims of the patent application. The claims define the scope of protection desired by the patent applicant and therefore focus on the key aspects of the innovation. In the data shown in Graph 5 we use the keywords “vanadium”, “bromine” and “chromium” to examine the prevalence of patent application relating to flow batteries having vanadium, zinc-bromine and iron-chromium chemistry.
It can be seen that while there have been increases in activity across the board, vanadium redox battery technology is the main focus of patent filing activity, particularly post-2014 where filings in the alternative chemistries fell back relative to vanadium.
Some patent search tools allow you to identify patents that are deemed to have high value. For example, if a patent filing is referenced many times when future patent applications are assessed against the prior art, it could be concluded that it contains subject matter highly relevant to the field.
Also, if a patent is registered in a wide range of countries, that may be indicative of high commercial relevance. A patent family may be deemed valuable if the patent renewal fees have continued to be paid to keep the patents in force, particularly in the later years of a patent’s 20-year term.
The patent family including European Patent EP 2 297 810 B scores as being valuable. The patent lists the proprietors as Massachusetts Institute of Technology and 24M Technologies, Inc.
The claims of the European patent define a redox flow energy storage device and, paraphrasing, define a positive and negative electrode current collector separated by a membrane and a positive electrode and a negative electrode. The claim culminates by stating “…wherein at least one of said positive and negative electrodes comprises a flowable electrode-active material comprising a semi-solid or condensed liquid ion-storing redox composition or redox compound in a flow electrolyte, the redox composition/compound being capable of taking up or releasing ions without dissolving in the flow electrolyte during operation of the device.”
Many of the family members are 15 years old and in force, and therefore likely to be seen as valuable by the owners.
The patent family, including EP 2 878 020 B to Lockheed Martin Advanced Energy Storage LLC, also scores high for being valuable and discloses “Electrochemical energy storage systems and methods featuring large negative half-cell potentials”.
Being aware of key patent rights in your field can help significantly when planning your R&D and commercial strategy in countries where the rights are in force.
Geographic coverage
Finally, turning to geographic coverage, patents are typically filed where the main markets are and where the main players are located. In the world of flow batteries, the top five countries/offices with the greatest number of flow battery patent filings are China, the US, South Korea, the European Patent Office and Japan.
In conclusion, the landscape of patent filings in the realm of flow battery technology is a testament to the rapid pace of innovation in this field. The surge in patent applications not only underscores the growing interest and investment in this technology but also highlights the competitive and collaborative environment that drives innovation.
The statistics explored in this article are not just numbers. They highlight the value companies place on their innovation and the need to ensure that the intellectual property supports the company as much as possible while the growing market of energy storage evolves.
