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ELECTRICITY STORAGE PATENTS Main patenting trends in electricity storage

From Nigel Charig

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This article presents the major trends in electricity storage innovation between 2000 and 2018. It shows how these are dominated by electrochemical battery developments, with electrical storage technologies also being present. We see the significance of battery innovation at both cell and battery pack levels, and consider the dominance of the automotive sector.

Between 2000 and 2018 more than 65000 IPFs relating to electricity storage were filed at patent offices worldwide.
Between 2000 and 2018 more than 65000 IPFs relating to electricity storage were filed at patent offices worldwide.
(Source: gemeinfrei / Pexels)

The unit of observation used is the IPF, which represents a unique invention and includes patent applications filed at two or more patent offices.

Between 2000 and 2018 more than 65000 IPFs relating to electricity storage were filed at patent offices worldwide. With nearly exponential growth, this represents a sevenfold increase, while the total number of IPFs per year in all sectors merely doubled during the same period.

Electrochemical battery technologies accounted for nine out of 10 of these IPFs, with electrical storage accounting for another 9 %. This category includes superconducting magnetic energy storage systems and supercapacitors. The remaining two categories of electricity storage technologies - thermal storage and mechanical storage technologies - account for just 5% and 3%, respectively, of all IPFs related to electricity storage. This is probably because technical progress has been mostly related to incremental innovation in these relatively mature and well-known fields.

Note that although their numbers are small, these technologies’ IPF growth rate was high until about 2012 – 2013, when they – and electrical storage IPF numbers – began to stagnate. Meanwhile, battery technology IPFs continued growing to a new height in 2018, so reinforcing the technology’s top position in the electricity storage innovation field.

The rise of innovation in batteries

Battery technology developments since 2000 have been mainly fueled by innovation at battery cell level. After stagnating at around 4100 IPFs per year between 2014 and 2017, the number of IPFs related to cells increased to 4851 (+17.5 %) in 2018, representing almost three-quarters of all battery-related developments during that year.

Other remarkable developments include technical progress made since 2000 in the thermal management of batteries and their integration into equipment, which are both key to facilitating battery use in new industrial applications. Recent acceleration in their development demonstrates modern batteries’ increasing applications possibilities.

Within battery cell IPFs, patenting activity has been growing for most key cell chemistries, including lead acid, redox flow, and nickel batteries. It is Li-ion technology, however, which has been fueling innovation in battery technologies since 2005; Li-ion is now the dominant technology for portable electronics and electric vehicles. In 2018, innovation in this field was responsible for 45 % of patenting activity related to battery cells, compared with just 7.3 % for other chemistries.

These trends in patenting rates coincide with price movements. Since 1995, Li-ion battery prices for consumer electronics have fallen by more than 90 %. For electric vehicles, Li-ion prices have declined by almost 90 % since 2010 alone, and for stationary applications, including electricity grid management, they have dropped by around two-thirds. These cost reductions are partly due to new chemistries, mostly adjustments to the composition of the battery cathode, as well as economies of scale in manufacturing.

However, innovation in manufacturing practices has also been essential. Patenting activity related to battery cell manufacturing and cell-related engineering developments has grown threefold over the last decade, increasing from fewer than 500 IPFs in 2009 to more than 1500 and 1400 IPFs, respectively, in 2018. These figures clearly indicate the industry’s maturity and the strategic importance of efficient industrialization for mass production.

Domination of the automotive sector – and spillover into other energy storage applications

Battery cells are typically produced as a commodity, designed for assembly into battery packs configured to deliver the right characteristics for the target end use. Therefore, patents related to battery packs indicate how batteries are penetrating diverse applications, even with common cell technology. Patenting activity related to battery packs increased from fewer than 100 IPFs in 2003 to more than 1000 in 2018. This reflects a level of technological maturity, as attention has shifted away from cell level developments towards optimizing use in highly demanding commercial markets such as the automotive sector.

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In fact, the automotive sector has come to dominate battery pack-related inventive activity, especially after 2009. 2017-2018 saw 736 IPFs related to electric vehicles, while developments in portable electronic battery pack designs and stationary applications have largely stagnated.

However, other applications will also benefit from automotive area inventive activity. For example, improvements to battery packs for all-electric and plug-in hybrid cars have had positive spillover effects on stationary applications in particular, many of which can reuse modified vehicle batteries that have reached the end of their vehicle life. Li-ion technology dominates both applications areas.

22 % of IPFs related to automotive battery packs can also be used for stationary and portable electronics, with 90 % of stationary application battery pack IPFs also being relevant to automotive applications.

Further work on spillovers could draw on citation data to identify the extent to which innovators build “on the shoulders of giants” in other technology fields. This has policy implications since a risk-averse policymaker may choose to incentivise the development of those technologies with a wide variety of applications.