A new class of electrochemically and thermally stable lithium salts for lithium battery electrolytes V. Synthesis and properties of lithium bis[2,3-pyridinediolato(2-)-O,O ']borate

Synthesis, analysis, and purification of lithium bis[2,3-pyridinediolato(2- )-O,O']borate (LBPB), is described. LBPB is the first lithium spiroborate k nown with a heterocycle, where the nitrogen works as an electron withdrawin g atom. The anodic oxidation limit of this salt as determined from cyclic v oltammetric measurements is 3.95 V vs. Li/Li+ and it is increased by about 0.35 V when compared with lithium bis[1,2-benzenediolato (2-)-O,O']borate. The gas phase energy of the highest occupied molecular orbital of the anion as obtained by the use of a semiempirical quantum mechanical method is -5. 1 eV. No corrosion of aluminum is observed with this salt, which shows good protecting properties for the lithium electrode; therefore, this electroly te may be suitable as an additive. (C) 2000 The Electrochemical Society. S0 013-4651(99)03-121-3. All rights reserved.