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

Abstract All solid state, thin-film batteries with the cell configuration of VO x /block copolymer electrolyte/Li have been designed, constructed, and tested. The additive-free (no carbon, no binder) cathode consisted of a dense film of vanadium oxide (∼200 nm thick), deposited on aluminum foil and prepared by laser assisted vapor deposition of vanadium metal in an oxygen atmosphere of controlled chemical potential. The electrolyte was a block copolymer of poly[oligo(oxy-ethylene) methacrylate]- b -poly-(methyl methacrylate) [hence forth denoted as POEM- b -PMMA] containing LiCF 3 SO 3 . The anode was metallic lithium. At room temperature, cathode capacities of ∼395 mAh/g were measured at a current rate of 0.5 C ( C =400 mA/g) over an operating 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 during the extended cycling (over 200 cycles). It was possible to draw substantial currents. Routine testing was conducted at 0.5 C ; however, discharge rates as high as 1.6 C were achieved. Based upon these results, cells designed with these materials in optimal dimensions are projected to have energy densities exceeding ∼350 Wh/kg and power densities exceeding 560 W/kg at 1.6 C .