Purpose This study aims to analyze and compare the convergence of rechargeable battery technologies in South Korea and the U.S.A. Methods Co-occurrence networks of international patent classification (IPC) codes have been analyzed and compared based on the rechargeable battery patents in South Korea and U.S.A during a 17-year period (2002-2017). Social network analysis methods have been applied to analyze the technology convergence and its characteristics on rechargeable batteries in both countries. In addition, the Word2Vec method has been utilized to better understand technology convergence. Results The results reveal that the strength of technology convergence has significantly increased centering on several core technologies during the period in both countries. While the convergence in the U.S.A has entered the maturity stage, the convergence in South Korea is still in the expansion stage. In addition, it was shown that the convergence pattern of the U.S.A. is more complicated and sophisticated. Conclusion This study showed the characteristics of technology convergence R&D in the rechargeable battery of two leading countries. The results of this study are expected to be used as a guideline to promote R&D in the rechargeable battery of South Korea.