**5. Discussion and conclusion**

The present findings drawn from the bibliometric and sentence-by-sentence analysis of 48 journal papers indicate that patents, as indicators or references alike, still occupy an irreplaceable position in tracking the rise of emerging technologies. Since 2001, a sequence of structural data extracted from patents, like counts, grants, or classifications, has been employed to assess industry structure and examine the patterns of technological change. Assignees, organizations, and portfolios involved in patents are analyzed to measure the R&D and commercialization aspects of innovation strategies. New technologies' forecasting has been increasingly produced by keywords and patent citations accompanied with the emergence of advanced data search and mining techniques. Details of e-mobility technologies, ranging from batteries to smart grids, are scrutinized as references based on patent documents. Contents are continuously being specified and updated in line with the overall trend in the development of e-mobility, accounting for elements behind pure statistics. Even the patent study on e-mobility has not already accumulated a remarkable number of publications; the potential topics revealed by extended use of recent highly citied papers are researchable, including the analysis of automotive supply industry, technology diffusion, and landscape as well as the evaluation of green innovation system and policies. A specific focus in latter the e-mobility patent study is to expound key technical problems regarding free-piston linear generator. Drivers, the current momentum, and policies are constantly analyzed to answer the question of how EV development is accelerated. However, limitations rooted in patent data concerning patentability, search engine, willingness to publish, and the IPC-based bias with the onesidedness of certain patent-based indicators mentioned as earlier should be noticed in further adoption of patents in e-mobility analysis, especially for improving its efficiency in plotting evolution of technologies and interpreting patents in a specific context. The limitation of such a study is that characteristics of patent study could not be fully identified because they are only identified from publications in an emerging field and the relevant search terms have not been unified in the past research. Nevertheless, it could be a sign of renewal when issues highlighted by those articles are explored in depth.

**Acknowledgements**

18/Recent commercial free-piston engine developments for automotive applications (reviewing commercial developments in freepiston engine systems by looking at recent publications and patent documents)

15/Identifying trends in battery technologies with regard to electric mobility: evidence from patenting activities along and across the battery value chain (applying patent families as technological indicators in order to analyze the research activities of each step of the designed battery value chain individually and in comparison with each other to identify and discuss trends regarding the technologies

9/Business strategies of incumbents in the market for electric vehicles: Opportunities and incentives for sustainable innovation (analyzing how environmental regulation and the firm's incentive and opportunity to innovate affected EV sales)

5/On the relation between communication and innovation activities: A comparison of hybrid electric and fuel cell vehicles (analyzing the relation between research and innovation activities and communication activities in the automotive industry using patent statistics, press releases, and

associated with electric vehicles)

**Author details**

Zhao Qu1,2\*

interviews)

Germany

The author would like to thank for financial support provided by the China Scholarship Council (No.201506060153), the National Science Foundation of China (No.71673036), and the

**Times cited/Tittle (purpose) Cited idea Further study**

"…discussed the basic features of a free-piston engine generator and the dynamics of the engine …"

Patent Research in a Period of Industry Transformation: A Focus on Electromobility

"…lithium-ion batteries have dominated very quickly…" "…the booming consumer electronics industry rapidly changed the economic and social

"…patent based studies have noted strong interest in radical innovation

"…finds the same contrasting technology strategies employed by electric passenger vehicle manufacturers and companies need both incentives and opportunities…"

"…vehicle electrification can ease environmental problems …" "…the changing perception of the hybrid technology led to a 'hybrid race' testified by the significant increase in patents…"

landscape…"

paths…"

Experimental study of a free-piston linear generator 145

http://dx.doi.org/10.5772/intechopen.75579

Patent study on the automotive supply industry, technologies' diffusion, technological distance, technology landscape, and innovation

Review the proposal of conceptual framework regarding green innovation

analysis on drivers, the current momentum, and policies for accelerating EV

system; evaluate environmental policy and

innovation

development

network

Consulting Project of Chinese Academy of Engineering (2016-XZ-03-05).

**Table 3.** Highly cited publications and cited ideas (times cited ≥5 since 2015).

1 Department of Social Sciences, Humboldt University of Berlin, Berlin, Germany

2 German Centre for Higher Education Research and Science Studies (DZHW), Berlin,

\*Address all correspondence to: zhaoqu@dzhw.eu


**Table 3.** Highly cited publications and cited ideas (times cited ≥5 since 2015).
