**4. Patent research on e-mobility**

#### **4.1. A bibliometric overview**

### *4.1.1. General trend and main research topics*

The earliest publication involved in the present data set could be traced back to 1993 [35] and the pressing environmental concern has renewed calls for a shift toward internationalization of e-mobility research since 2012. Even the number of patent researches is limited, the sources are relatively scattered (132 authors from 58 affiliations), and their collaborations could not be captured in an extensive network (only 3 authors are engaged in the co-authorship more than once). In **Figure 1** 323 authors' keywords are cleaned up manually considering the problem of variants (e.g., "electric vehicles" and "EVs") and then 48 terms meeting the threshold (occurrences ≥2) are processed into 6 main clusters and colored using average publication year by VOSviewer. Patents have been employed to reveal the hype cycle for emerging technologies between 2001 and 2013 and then are discussed by introducing novel techniques (e.g., Google search) after 2014. Terms of "innovation" and "EV" as key nodes have been continuously

<sup>1</sup> Each term in the present query is sorted and filtered based on expert advice received from National Science Foundation of China (No.71673036) and Consulting Project of Chinese Academy of Engineering (2016-XZ-03-05).

Patent Research in a Period of Industry Transformation: A Focus on Electromobility http://dx.doi.org/10.5772/intechopen.75579 141

**Figure 1.** Co-occurrence analysis of keywords with average publication year.

explored ranging from the topics of patent-based indicators and approaches to technologies and the automotive industry as well as green products and market since 2013. Recently, the focus of patent research lies with the emergence of hybrid devices. E-mobility issues are inevitably tied to carbon emissions, efficient strategy, and sustainable development, which is proved in cluster 5 and 6.

#### *4.1.2. Citation-based knowledge flows*

can these patterns be interpreted?" which enable us to analyze structures and dynamics of fields [31, 32]. Forty-eight articles in English identified by merging the query of terms<sup>1</sup> in the scope of e-mobility (e.g., electric vehicles, hybrid electric vehicle, etc.) with the topic search of patent (TS = patent\*) from the Web of Science™ Core Collection (WoS) database up to 2017 are discussed in this chapter aiming to investigate the current progress of patent research on e-mobility. Visualizations are addressed throughout the discussion by explaining how they are produced and how they can be interpreted. Extrinsic data to the text such as the publication year, keywords, and citations are synthetically measured in a co-occurrence analysis, a technique that captures the frequency of pairs of words, phrases, or references in and between articles [33]. The first step is to represent the association of research topics and to observe the progress along with the time, source, and flow of knowledge, eventually to understand the development of scientific fields. The common base and expansion of knowledge are structured through backward and forward references by performing a co-citation and bibliographic coupling analysis, respectively, and the former depends on the frequency when two documents are cited together whereas the latter occurs when two works reference a common third work [33, 34]. Then, intrinsic information regarding the reason for performing patent analysis of e-mobility issues, research limitations, and trends dug out from abstracts, methods, conclusive parts, and recent highly cited papers are collected and categorized on a sentence-by-sentence basis in order to advocate for greater attention to article content in addi-

The earliest publication involved in the present data set could be traced back to 1993 [35] and the pressing environmental concern has renewed calls for a shift toward internationalization of e-mobility research since 2012. Even the number of patent researches is limited, the sources are relatively scattered (132 authors from 58 affiliations), and their collaborations could not be captured in an extensive network (only 3 authors are engaged in the co-authorship more than once). In **Figure 1** 323 authors' keywords are cleaned up manually considering the problem of variants (e.g., "electric vehicles" and "EVs") and then 48 terms meeting the threshold (occurrences ≥2) are processed into 6 main clusters and colored using average publication year by VOSviewer. Patents have been employed to reveal the hype cycle for emerging technologies between 2001 and 2013 and then are discussed by introducing novel techniques (e.g., Google search) after 2014. Terms of "innovation" and "EV" as key nodes have been continuously

Each term in the present query is sorted and filtered based on expert advice received from National Science Foundation

of China (No.71673036) and Consulting Project of Chinese Academy of Engineering (2016-XZ-03-05).

tion to the bibliometric analysis.

140 Scientometrics

**4.1. A bibliometric overview**

1

**4. Patent research on e-mobility**

*4.1.1. General trend and main research topics*

Filtered by the minimum number of citations, 51 of 1788 references are collected and form four main clusters (**Figure 2**). The paper published by van den Hoed in 2005 [36] is represented as a key node among a group of emerging technology-based studies in red at the interface between discussions on emerging eco-innovation evaluation (green nodes on the top) and the cluster of papers adopting patent-based indicators in measuring technological change (yellow nodes in the middle). Note that citation is more frequent and probably more disciplined on the overall innovation performance research side, which also provides us with different kinds of evidence for the deficiency in e-mobility patent study. Among the technological forecasting-focused papers on the right side of **Figure 2** (blue nodes), the co-citation analysis highlights authors [37–39] who have engaged in discussions with the joint use of bibliometric and patent analysis. The first cluster indicated in red is led by research from van den Hoed and Bakker [36, 40], who share an interest in the development of fuel cell technology. Citations categorized into the second cluster have an earlier average publication year than that of the first cluster, including studies on e-mobility innovation coupled with policy, economic, and

**Figure 2.** Co-citation analysis of references listed in 48 papers.

technology analysis [41–43]. Patent citation analysis is the central topic of discussion involved in the fourth cluster with the earliest average publication year of 2000 [44–46]. Namely, the core documents providing a common knowledge base for e-mobility patent study are relatively new and it is partly an effect of emerging technologies and the changing field.

**4.3. Limitations and potential topics**

Classifications (IPC)

Some of the deficiencies inherent in patent research are synthesized and divided into groups of limitations regarding patents or data sources [21, 53, 54] and patent-based indicators or approaches [47, 55, 56], respectively, thereby pinpointing areas of improvement in the further study on e-mobility. However, the following limitations should not be viewed in isolation, and the specificity of e-mobility field, especially the novelty and complexity of technologies

Patent documents include potential information on developed technologies

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

143

Patent—pending applications,

To describe technology in detail; explore technology clusters; give an indication as to main technical challenges for the relevant technology; assess technological evolvement or accelerate literature-based science discovery

abstracts, literatures

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

A series of up-to-date topics captured from citing articles based on recent highly cited ones in **Table 3** could be classified into the extension of the specific technology discussion, patent-based analysis, and research on innovation system or policies in the field of e-mobility [47, 57–62]. The classification of additional research perspectives is inevitably influenced by the usage of patent in highly cited papers (**Table 1**). More specifically, a review on patented technologies has developed the base for further experimental studies, and papers adopting patent-based indicators could arouse growing interests in examining the pattern of technological change [21, 63]. Patents combined with other format of data, such as scientific literatures, surveys, interviews, or press releases, may contribute to a more comprehensive understanding of relevant policy and innovation system

[19, 21], needs to be considered in addition to patent-oriented issues (**Table 2**).

Reasons Patent as the proxy for innovative output is the most common way in the automotive industry to protect intellectual property.

> and priority years, publications, citation networks, assignees, organizations, portfolios, keywords, International Patent

technological change; forecast diffusion or adoption patterns of new technologies; understand technology maturity; evaluate the effectiveness of technology-forcing policies; measure the incentive and opportunity to innovate; operationalize the R&D and commercialization aspects of innovation strategies; study the relationship between competitive forces and technological development; propose a predictive model of the patent registration time; find differences between patents and research publications for technology road mapping; filter the irrelevant patent citations;

**Table 1.** The usage of patent in an e-mobility study extracted from abstracts and methods.

Measures Patent—applications, counts, grants, families, origin countries

Aims To assess industry structure; examine the patterns of

and verify components of the hype cycle

*4.3.1. Recent research limitations*

*4.3.2. Potential topics*

research [48, 54].

By contrast, an analogous network structure could not be found through a bibliographic coupling analysis of 462 citing papers owing to the unclear layout of nodes and their links. It may indicate that the knowledge of these 48 patent studies is expanded to a much broader scientific field with more creative and diverse approaches to exploring e-mobility issues. Moreover, the share of self-citations is comparatively high and implies that there has existed specific groups of authors in this research area and their studies possess certain coherence.
