| Electrolytes for Sodium Batteries: A Patent Landscape Analysis of Material Platforms and Their Transitions |
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Kyeong-Weon Park1,2, Dong-Won Kim1,3 |
1Department of Chemical Engineering, Hanyang University, Seoul 04763, Republic of Korea
2WOOGIN IP Law Firm, Seoul 06241, Republic of Korea
3Department of Battery Engineering, Hanyang University, Seoul 04763, Republic of Korea |
Correspondence:
Dong-Won Kim,
Email: dongwonkim@hanyang.ac.kr
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Received: 4 August 2026 • Accepted: 8 September 2026 |
| Abstract |
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Sodium batteries are attracting increasing attention as cost-effective alternatives to lithium-ion batteries, particularly for large-scale stationary energy storage. Their development has followed two technological pathways, high-temperature molten-sodium batteries and room-temperature sodium-ion batteries, which are fundamentally differentiated by their electrolyte systems. This review presents a comprehensive patent-based analysis of electrolyte chemistry, providing valuable insights into the evolution of sodium battery technologies. A title-based search yielded 9,563 patent families, which were consolidated based on their earliest priority dates. Candidate patents were screened using a two-stage workflow consisting of deterministic keyword filtering based on a bilingual dictionary, followed by large language model-assisted evaluation of complete patent claims. This process identified 1,068 patent families in which sodium electrolytes constituted the primary invention. The patent families were classified into three electrolyte categories: liquid, gel/polymer, and inorganic solid electrolytes. Patent activity was grouped into five segments, revealing three distinct development periods separated by a pronounced decline between 2005 and 2009. Liquid electrolytes accounted for 71.3% of filings in the most recent period, while inorganic solid electrolytes simultaneously reached their highest absolute filing level, indicating diversification rather than replacement. Within solid electrolytes, β/β″-alumina declined from 97.8% to 10.5% of filings, whereas NASICON-type oxides increased from zero to 41.1%, overtaking β/β″-alumina in the fourth period. Furthermore, applicant- and jurisdiction-level portfolios exhibited substantially greater specialization than suggested by aggregate trends, highlighting the importance of sub-type-level analysis for understanding technological evolution. |
| Keywords:
Sodium battery, Electrolyte, Patent landscape analysis |
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