## 3 Results
### Multi-Dimensional Scaling (MDS)  
MDS is a great visualization tool to discover technology similarity. By observing the calculated point position in the X-Y coordinate diagram, it is clear and convenient to explore the similarity/dissimilarity of specific technology among several companies. For example, if the LiPF\({}_{6}\) or lithium hexafluorophosphate is disclosed one time in the claim, and the term is classified to lithium salts technology once. It is interesting to note that several compounds, for example, carbonate, lactose, ester, can be seen either as organic solvents or additives depending on the required amount in the electrolyte. Therefore, organic solvents and additives are organized in the same figure. Figure 5a,b illustrates the MDS results of lithium salts and organic solvents and additives. Six colors are used to represent six patent assignees. The bubble and the number next to it shows that the occurrence frequency of words related to specific technology appears in the claims of all issued patents from one company. LG Chem. and Samsung SDI had much closer positions in Figure 5a. It means that there are many similarities in their lithium salts technologies. The points of Ube, Panasonic, and Sony were also close to each other. It also indicates that their inventions in lithium salts are somewhat similar. The result could be relevant to the results in the citation analysis, where inorganic salts, e.g., LiPF\({}_{6}\), LiClO\({}_{4}\), and lithium sulfonamide organic salts such as LiN(CF\({}_{3}\)SO\({}_{2}\))\({}_{2}\), were commonly used together in all the top 10 patents. Interestingly, Mitsubishi Chem. was far away from other patent assignees, showing that Mitsubishi Chem. 's lithium salts technology was more specialized. Referring to the finding in the citation-based method, novel lithium cyclic disulfonylimide compounds were to mix with other lithium salts. This lithium salt was different from other companies' usage. Figure 5b shows that the points of six patent assignees were independent in the X-Y coordinate diagram. It means that their organic solvents and additives technologies were dissimilarities. It further indicates that they developed different organic solvents and additives materials. The result could be identified in the \begin{table}
\begin{tabular}{c c c} \hline \hline
**Patent Assignee** & **Additive Compounds in the Electrolyte** & **F-Terms** \\
**Patent Number** & & **(Functions)** \\ \hline Mitsubishi Chem. & 1. overcharge preventing agent, e.g., biphenyl, an alkylbiphenyl, terphenyl, a partially hydrogenated product of terphenyl, cyclohexylbenzene. & AJ02, AJ03, AJ04, AJ05 \\ US7083878B2 & 2. assistant, e.g., carbonate compound, vinylethylene carbonate, trifluoropropylene carbonate. & AJ05 \\ \hline Panasonic US6958198B2 & 1. fluorine-containing compound, e.g., fluoroalkyl(C2-C20)carboxylic acids, fluoroalkyl(C2-C20)-carboxylic acids, disodium N-perfluoroactesulfonylglutamate. & AJ02, AJ04, AJ05 \\  & 2. carbonic acid ester, e.g., vinylene carbonate, phenylethylc carbonate, phenylvimice carbonate. & AJ02, AJ04, AJ05 \\  & 3. sulfur compound, e.g., ethylene sulfite, ethylene trithiocarbonate, vinylene trithiocarbonate. & AJ02, AJ04, AJ05 \\ \hline Samsung SDI US7205073B2 & 1. a compound represented by the Formula (1), e.g., 3-fluoroanisole, 3-chloroanisole, 3-bromoanisole. & AJ02, AJ12 \\  & 2. a compound selected from the group consisting of a sulfone-based compound, a poly(ester)(metha)acrylate, a polymer of a poly(ester)(metha)acrylate. & AJ02, AJ12 \\ \hline LG Chem. & EDTA (ethylene diamine tetraacetic acid), NTA (nitrilotriacetic acid), DCTA (trans-1,2-diaminocyclohexanetetraacetic acid), DTPA (diethylene-triamine pentaacetic acid), and EGTA & AJ12 \\  & (ethylene glycol bis(2-aminoethyl) & AJ12 \\  & ether)-N,N,N’,N’-tetraacetic acid). & AJ12 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Information of representative patents.