Japanese Patent Office Upholds Validity of Mitsubishi Chemical’s Patent on Electrolyte for Lithium Ion Battery ensuing from review in an Opposition

Mitsubishi Chemical Corporation (MCC; Head office:  Chiyoda-ku, Tokyo; President; Masayuki Waga) announced today that the Japan Patent Office (JPO) issued a notice upholding the validity of a key MCC electrolyte patent.  The official notice, which was issued on July 13,2020, rejected arguments filed in a third party opposition challenging the validity of MCC’s JP Patent 5987431, which covers an innovative electrolyte used in lithium ion batteries.  The panel of JPO administrative judges sided with MCC’s position, affirming the validity of the patent.


The patent had been challenged by a third party (Opposition case number 2017-700208), and in initial proceedings, was reached to revoke the patent.  MCC appealed the decision to the Intellectual Property High Court (case number:  Heisei 30 Gyo Ke 10170), which overturned the initial decision.  In light of the High Court decision, the JPO panel reviewed the prior decision and issued the decision to maintain the patent and affirm its validity, a significant victory for MCC.


MCC, an established world leader in the market, has developed a variety of novel additives that enhance the performance of electrolytes for lithium ion batteries. The patent at issue covers innovations that provide electric vehicles improved durability, high output and excellent recharging properties.   These JPO and High Court decisions are a significant victory for MCC’s business, and affirm MCC’s innovations and preserve MCC’s enforcement rights against those who copy its protected technology.   MCC has continued to invest substantial resources in the development of innovative products and solutions, and the associated patent portfolio, with the goal of providing creative solutions that enhance the lives of all members of society.

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