Enhanced High-Temperature Storage Performance of Li-Ion Batteries Using Stoba Polymer Coated on a Lithium Transition Metal Oxide Cathode Material

ITRI in Taiwan has developed a polymeric cathode coating material, known as self-terminated oligomer with hyper-branched architecture (STOBA) can improve the safety and high temperature cycle ability, also can suppress the thermal runaway. In this research, the STOBA was coated on a mixture of  NMC and LMO. 18650-type cells test show the capacity recovery ratio after storage for 30 days at 55°C, the batteries without  STOBA-coating have large capacity deterioration than with STOBA. Furthermore, the batteries were dissemble after aging, the electrolyte was analyzed by ICP, dissoluted Mn ion was detected in the electrolyte solution. The Mn dissolution quantity of mixture electrode without STOBA coating almost 2 time larger than the sample with 2 wt.% STOBA coating electrode. Mn dissolution of mixture electrode restrained by STOBA coating. In the XPS analysis, the sample with STOBA has less percentage of LiF content compare to the sample without STOBA coating. STOBA coating can suppress the decomposition of LiPF₆. In a word, the STOBA coating on the electrode not only can restrain the Mn dissolution but also suppress the LiPF₆ decomposition. Then, to improve the high-temperature storage performance of Li ion batteries.