화학공학소재연구정보센터
Journal of Power Sources, Vol.79, No.1, 91-96, 1999
Chelate complexes with boron as lithium salts for lithium battery electrolytes
The electrolytic conductivity and charge-discharge characteristics of lithium electrodes are examined in propylene carbonate (PC)and ethylene carbonate (EC)-based binary solvent electrolytes containing lithium bis[l,2-benzenediolato(2-)-O,O']borate (LBBB), lithium bis[2,3-naphthalenediolato(2-)-O,O']borate (LBNB) and lithium bis[2,2'-biphenyldiolato(2-)-O,O']borate (LBBPB). The LBBPB exhibits high thermal and electrochemical stability compared with LBBB and LBNB. Conductivities in PC-THF and EC-THF binary solvent electrolytes at X-THF (mole fraction of tetrahydrofuran, THF) = 0.5 containing 0.5 M LBBB and LBNB are nearly equal to that in 0.5 M LiCF3SO3 electrolyte as a typical lithium battery electrolyte. The conductivity in 0.3 M LBBPB/PC-DME (DME: 1,2-dimethoxyethane) electrolyte is fairly low compared with that in other electrolytes. The energy density with the LBNB electrolyte is higher than that with LBBB or LBBPB electrolyte. In general, lithium cycling efficiencies in THF-based LBBB and LBNB electrolytes become higher than those in DME-based electrolytes. The 0.5 M LBNB/PC-THF electrolyte is a moderately rechargeable lithium battery electrolyte. The 0.3 M LBBPB/PC-DME equimolar solvent electrolyte displays the highest cycling efficiency, viz., > 70%, at a high range of cycle number.