This paper analyzes the patent application trends and technology lifecycle of high-specific-performance high-voltage lithium battery packs, identifies the geographical distribution of patent applications and major global patent applicants, and guides relevant research institutions to effectively plan their patent portfolios and prevent patent disputes, thereby reducing the risk of patent infringement during the R&D process. Simultaneously, it seeks technological innovation in key R&D directions through technical efficacy analysis.
Keywords: lithium battery; patent analysis; applicant; patent layout
High specific energy and high voltage are two important performance parameters of lithium batteries. High specific energy is also called high specific energy. Generally, the specific energy of lithium batteries is required to reach more than 100W·h/kg. High voltage requires the voltage of a single lithium battery to be above 3V[1]. High specific energy high voltage lithium battery packs are currently the most promising high-efficiency secondary batteries and the fastest-growing chemical energy storage power sources. They are widely used in various aspects of energy storage fields such as power transmission and distribution, aerospace, auxiliary services, distributed microgrids, industry, renewable energy grid connection and electric vehicle charging and swapping[2]. With the rapid development of the power industry, the market demand for lithium battery energy storage technology will maintain a high-speed upward trend, and the research on high specific energy high voltage energy storage batteries has become a hot technology for countries to compete for. The important technologies of high specific energy high voltage lithium battery packs include electrode material technology, electrolyte technology, battery pack management technology, etc.[3]. This paper analyzes the patents from multiple perspectives such as the patent application trend, regional distribution, applicants, and technical efficacy of high specific energy high voltage lithium battery packs. This is helpful to guide relevant companies to find technical research and development ideas from high-value patents, and at the same time reduce the intellectual property risks in the process of technical research and development.
1. Patent Analysis Methods
The construction of a technology spectrum is the foundation for the correct formulation of patent search strategies. By constructing a technology spectrum, the accuracy of patent search can be achieved. In this paper, combined with the specific application environment of high-specific-value high-voltage lithium battery pack technology, a technology spectrum is formulated as shown in Table 1. The high-specific-value high-voltage lithium battery pack technology is decomposed into two secondary technologies: battery pack technology and fault tolerance management technology. The tertiary technology is a further decomposition of the secondary technologies.
Table 1. Technology spectrum of high-specific-performance high-voltage lithium battery packs
Table1Technicalpedigreeofhigh-specificationandhigh-voltagelithium-ionbatterypack
Using the Incopat patent database as the base database, we conducted a global search of each technology branch in the technology spectrum. Considering factors such as patent citation frequency, number of patent families, first-time applications for important technologies, and applications involving legal issues, and incorporating the opinions of technical experts, we classified, statistically analyzed, and manually reviewed 566 relevant patents. (Due to the time lag in patent publication, the data for the past two years is incomplete and is for reference only. The same applies below.)
2. Patent Application Trend Analysis
Figure 1 shows the annual patent application trend for high-specific-performance high-voltage lithium-ion battery packs, including global and Chinese patent application trends. This trend reflects the level of attention and technological development of high-specific-performance high-voltage lithium-ion battery packs. The patent application trend for high-specific-performance high-voltage lithium-ion battery packs has roughly gone through three important stages.
Figure 1. Patent application trends for high-specific-performance high-voltage lithium battery packs
Fig.1Patentapplicationtrendofhigh-specificationandhigh-voltagelithium-ionbatterypack
The number of patent applications has stabilized after an initial rise, with only a slight decrease in the number of applicants in 2014 compared to the previous year, which does not indicate an overall trend of decreasing applicants. Overall, the technology sector is still in a growth phase.
Figure 2. Technology lifecycle diagram of high specific performance high voltage lithium battery pack
Fig.2Technicallifecyclediagramofhigh-specificationandhigh-voltagelithium-ionbatterypack
4. Patent Application Regional Analysis
In addition to patent protection in their home country, patent applicants often apply for patent families abroad in order to obtain intellectual property protection for the production and sale of products abroad. Therefore, the number of patents in a country in a specific technical field generally reflects the market prospects and degree of competition in that specific field[6]. By analyzing the patent application regions in the field of high specific characteristics high voltage lithium battery pack technology, the technical strength and market prospects of various countries and regions are revealed. Figure 3 analyzes the important patent application regions of high specific characteristics high voltage lithium battery pack. my country ranks first in the number of patent applications, with 312 patent applications, accounting for 55.12% of the total number of patent applications; Japan ranks second in the number of patent applications, indicating that Japanese applicants also have obvious technical advantages; South Korea ranks third and the United States ranks fourth. This is because South Korea has developed rapidly in the field of lithium batteries, and therefore, South Korea has also become an important patent application country.
Figure 3. Important Patent Application Countries/Regions
Fig.3Majorpatentapplicationcountriesandregions
Analysis of 5 key applicants
As shown in Figure 4, a statistical analysis was conducted on applicants with 10 or more patent applications for high-specific-value high-voltage lithium battery packs. There were 11 applicants in total. The data shows that globally, applicants with 10 or more applications include 6 Japanese companies, 3 Chinese companies, 1 British company, and 1 South Korean company. Although my country's patent applications are significantly ahead of Japan's in terms of the number of patent applications, there is still a large gap between my country and Japan in terms of important applicants. my country's patent applicants are more dispersed, resulting in fewer patent applications from each applicant. In contrast, Japan's patent applicants are more concentrated, forming a situation where companies with technological advantages dominate technology research and development. Among the important patent applicants, Sumitomo Corporation of Japan has 28 patent applications, which is nearly twice the number of patent applications from Shanghai Space Power Research Institute, which ranks second. This shows that Sumitomo Corporation is in a leading position in the technological research and development of lithium batteries. BAE Systems of the United Kingdom is a company whose patent applications were filed earlier and whose technologies are mostly related to technology [7]. LG Chem of South Korea has reached the world's advanced level in lithium battery manufacturing technology, but its competitiveness in materials and core technologies is not as good as that of Japan.
Figure 4 Ranking of Key Applicants
Fig. 4 Ranking of main applicants
With the support of basic research and technological development, my country’s high-specific-value high-voltage lithium battery technology has made great progress, and the number of major applicants is second only to Japan[8]. The Shanghai Space Power Research Institute and the 18th Research Institute of my country Electronics Technology Group Corporation have advanced R&D capabilities in the field of space power technology. CATL has reached the international advanced level in the fields of power and energy storage batteries, materials, cells and battery systems.
Figure 5 analyzes the important target countries of important applicants. The data shows that the applicants have the largest proportion of targeting countries. For example, Japanese companies such as Sumitomo, Sony, Panasonic and Toyota attach great importance to their patent layout in Japan. However, Mitsubishi Chemical's patent layout is different from other Japanese companies. It has 10 patents in my country and only 1 patent in Japan. Further analysis shows that the 10 patents applied for by Mitsubishi Chemical in my country are actually 2 patent families. LG Chem of South Korea has patent layouts in my country, the United States and South Korea. Moreover, the number of patent applications in the United States and South Korea is more than the number of patent applications in my country, indicating that LG Chem attaches more importance to patent layouts in the United States and South Korea [9]. BAE Systems of the United Kingdom has a relatively extensive patent layout. It has a certain number of patent applications in my country, Japan, the United States and South Korea. Among the domestic applicants, the Shanghai Space Power Source Research Institute and the 18th Research Institute of my country Electronics Technology Group Corporation have limited their patent portfolios to domestic applications and have not yet filed patents overseas. This is because these two institutions are organizations whose products are mainly used in the field and therefore do not pay attention to overseas patent portfolios. In contrast, CATL has filed a large number of patents in China and has also filed relevant patents in Japan and the United States because its products are also targeted at the international market.
Figure 5. Analysis of Patent Layout of Key Applicants
Fig.5Analysisofpatentlayoutofmainapplicants
6. Technical Efficacy Analysis
For 566 high-specific-characteristic high-voltage lithium battery pack patents, after indexing according to technical means and technical effects, the lithium battery technology efficacy diagram shown in Figure 6 is obtained. From the perspective of technical means, high-power electrolyte technology and high-power electrode material technology are the key points of the patent technology layout of high-specific-characteristic high-voltage lithium battery packs, accounting for 43.1% and 37.8% of the total number of patent applications, respectively. High-power electrolyte and high-power electrode material are the foundation of high-specific-characteristic high-voltage lithium battery technology, and domestic and foreign applicants have already laid out a large number of patents in this field. Secondly, the field of equalization management technology is the focus of battery pack management technology and also the key technology to improve the life of high-voltage battery packs [10].
Figure 6. Technical efficacy diagram of high specific performance high voltage lithium battery pack.
Fig.6Technologyeffectdiagramofhigh-efficiencyandhigh-voltagelithium-ionbatterypack
From a technical perspective, improving the reliability and power of high-voltage lithium battery packs is a key achievement of lithium battery patents. Improving reliability includes enhancing high-voltage safety and high-temperature stability, while improving power includes increasing high-rate discharge, conductivity, and discharge specific capacity. Secondly, improving battery pack performance and lifespan is also a focus of patent portfolio development. Improving performance includes enhancing conductivity and high-temperature cycle performance, while improving lifespan has always been a goal in lithium battery technology, directly impacting the lifespan of high-specific-capacity high-voltage lithium battery packs. Furthermore, improving battery pack reliability and lifespan is closely related, often achieved simultaneously through the same technical means.
Specifically, the technical effects achieved by various technologies differ. High-power electrode materials and high-power electrolytes primarily address the power and performance issues of lithium batteries, improving the power and performance of individual lithium cells to enhance the high-voltage performance and high-voltage characteristics of the lithium-ion battery pack. Balance management, on the other hand, ensures that each individual cell in the battery pack reaches a consistent equilibrium state, thereby improving the battery pack's lifespan and reliability. Furthermore, by selecting an appropriate balance method, the efficiency of battery balancing can be improved.
High-voltage lithium batteries rely on high-power electrode materials and high-power electrolytes. Among high-power electrode materials, patents for positive electrode materials account for 58.54% of the total patent applications, higher than those for negative electrode materials, as shown in Figure 7. Ternary materials account for the highest proportion of patent applications among positive electrode materials, reaching 17.03%. Due to their high energy density and other advantages, ternary materials have become a research hotspot for positive electrode materials, followed by cobalt-based materials, accounting for 10.46%. Patent applications for negative electrode materials account for 29.20%, among which carbon materials, with their high specific capacity, low electrode potential, and high cycle efficiency, remain a research hotspot and a key area for patent applications. Silicon-based materials, with their high energy density and low electrochemical potential, have also seen a certain proportion of patent applications in recent years.
Figure 7. Distribution of patent technologies for high-power electrode materials
Fig.7Patentapplicationtechnologydistributionofhighpowerelectrodematerial
Figure 8 shows the technology distribution of patent applications for high-power electrolytes. As can be seen from the figure, the number of patent applications in the field of additives is the largest, accounting for 59.06%. Among them, patent applications related to high power are the main body of additive patent applications, accounting for 31.16% of the total number of patent applications. Among organic solvent patent applications, carbonate patent applications have the highest proportion, followed by fluorinated solvents. The number of patent applications in the field of lithium salts is relatively small, accounting for 14.86% of the total number of patent applications.
Figure 8. Distribution of patented technologies for high-power electrolytes
Fig.8Patentapplicationtechnologydistributionofhighpowerelectrolyte
7 Conclusions
The patent analysis above shows that, after initial accumulation, patent applications related to high-specific-performance high-voltage lithium battery packs are still on the rise, indicating that the technology is still in a phase of rapid development. The key aspects of patent strategy for high-specific-performance high-voltage lithium battery packs can be summarized in the following two areas.
(1) High-power electrode materials and electrolytes are the foundation of high-voltage battery pack technology. High-specific-performance high-voltage lithium battery packs are obtained by connecting high-voltage single-cell lithium batteries in series, and high-voltage single-cell lithium batteries rely on high-power electrode materials, especially high-power electrode materials and high-power electrolytes. Patent analysis information shows that high-power electrode materials and electrolytes are the focus of patent layout. Domestic and foreign applicants have added graphene as an electrode conductive agent to lithium-ion electrode materials to improve the conductivity of electrode materials and increase the power of lithium batteries. This technology is now mature.
(2) Active balancing technology is the focus of current battery pack balancing management technology patent layout, and hybrid balancing technology has great potential in the future. Among the patent applications for high specific characteristics high voltage lithium battery pack management technology, the patent application volume of the technology branch of balancing management technology (including hybrid balancing management technology, active balancing management technology and passive balancing management technology) is the largest, accounting for 75.8% of the total patent applications, which shows that balancing management technology is the key to battery pack management technology [11]. Among them, most high voltage lithium-ion battery packs adopt active balancing, and among the patent applications for balancing management technology, active balancing management technology has the largest number of patent applications, accounting for 57.58%. In addition, hybrid balancing technology inherits the advantages of active balancing and effectively combines active balancing and passive balancing, which can effectively extend the battery pack life and has become a hot spot for balancing management technology patent applications in recent years, with great potential for future development.
