High energy density, thin-film, rechargeable lithium batteries for marine field operations

All solid state, thin-film batteries with the cell configuration of VOx/blo ck copolymer electrolyte/Li have been designed, constructed, and tested. Th e additive-free (no carbon, no binder) cathode consisted of a dense film of vanadium oxide (similar to 200 nm thick), deposited on aluminum foil and p repared by laser assisted vapor deposition of vanadium metal in an oxygen a tmosphere of controlled chemical potential. The electrolyte was a block cop olymer of poly[oligo(oxy-ethylene) methacrylate]-b-poly-(methyl methacrylat e) [hence forth denoted as POEM-b-PMMA] containing LiCF3SO3, The anode was metallic lithium. At room temperature, cathode capacities of similar to 395 mAh/g were measured at a current rate of 0.5C (C = 400 mA/g) over an opera ting voltage ranging from 1.5 to 4.0 V. The cathode proved to be resistant to capacity fade as evidenced by the small loss of discharge capacity durin g the extended cycling (over 200 cycles). It was possible to draw substanti al currents. Routine testing was conducted at 0.5C; however, discharge rate s as high as 1.6C were achieved. Based upon these results, cells designed w ith these materials in optimal dimensions are projected to have energy dens ities exceeding similar to 350 Wh/kg and power densities exceeding 560 W/kg at 1.6C. (C) 2001 Elsevier Science B.V. All rights reserved.