M.Z.A. Munshi

Performance of polymer electrolyte cells at +25 to +100°C

Solid-state rechargeable polymer-electrolyte batteries utilizing lithium anodes and V/sub 6/0/sub 13/ composite cathodes were investigated at 100 C. The polymer electrolyte was a complex formed between polyethylene oxide (PEO) and LiCF/sub 3/SO/sub 3/. Over a hundred cycles were obtained at the C/5 rate (45% depth of discharge) with greater than 75% of the initial capacity of V/sub 6/0/sub 13/ being maintained at cycle number one-hundred. Cells made with propylene carbonate (PC)-doped polymer electrolyte also showed good performance at room temperature.

Sodium / V 6 O 13 Polymer Electrolyte Cells

Although lithium anodes offer many attractive features such as high energy density and high negative electrode potentials, the advantages may be overshadowed by the disadvantages. The use of sodium anodes may be an attractive alternative therefore that is explored in the present research. Apart from work on the Na/S battery, the investigation of sodium secondary battery systems has been slow because of the stability problems experienced by the sodium anodes in most organic electrolytes. In this paper, the behavior of the cell Na/PEO/sub 8/.NaCF/sub 3/SO/sub 3//V/sub 6/O/sub 13/, operating at 95{sup 0}C is described.

Applications of Multivalent Ionic Conductors to Polymeric Electrolyte Batteries.

Fast-ion conduction has been demonstrated in certain polymer materials doped with an alkali metal salt. Recently, divalent salts have also been used in the preparation of ionically conducting polymers. Certain complexes were found to be anion conductors while others were cation conductors. It is, therefore, of interest to study the reasons for the apparent difference. Alternating-current measurements are currently being evaluated on a number of polymer divalent salt complexes. Electrochemical cells are being constructed with appropriate cathodes to assess the feasibility of these polymer electrolytes in rechargeable batteries.

Assessment of thin film batteries based on polymer electrolytes. I. Energy density

Abstract The theoretical energy density performance limits for packaged rechargeable lithium polymer electrolyte batteries of both prismatic unipolar and bipolar electrode configurations are discussed. The electrolyte is based on complexes formed between polyethylene oxide and a lithium salt, and the composite cathode is V6O13. The modeling study suggests that specific energies up to 450 Wh/kg are possible for packaged batteries based on both unipolar and bipolar cell designs. This requires the use of low density metallic or metallized plastic current collectors.

Insertion reactions of sodium in V6O13 single crystals from a solid polymeric electrolyte

Abstract The compositional variation of the kinetic and thermodynamic processes of sodium insertion into V 6 O 13 single crystal electrodes have been examined using cells of the type Na| (PEO) 8 ·NaCF 3 SO 3 |V 6 SO 13 over a range of temperature and stoichiometry. Coulometric titration and ac impedance data have shown sodium to be highly stable and reversible to V 6 O 13 . The chemical diffusion coefficient was found to be fairly constant over a wide stoichiometry range with a mean value of about 2.9 ×10 −8 cm 2 s −1 .

Ambient temperature solid polymer electrolyte devices

Abstract Poly(ethylene oxide) based solid polymer electrolytes with lithium bis-perfluoro-acyl-imide and lithium bis-perfluoro-sulfonylimide plasticizer salts have been investigated by complex impedance analysis, differential scanning calorimetry and electrochemical performance in the Li/V 6 O 13 electrode couple environment. Poly(ethylene oxide)-poly(ethylene glycol) based composite polymer blends with LiCF 3 SO 3 salt were also studied as possible ambient temperature electrolytes. A third group of polymer electrolytes based on lithium salts doped into non-aqueous gels were found to possess an ionic conductivity of 4.5×10 −4 S cm at 22°C. The material was used as an electrolyte in the fabrication of a thin film electrochemical cell (6.5 cm 2 area) with the Li/V 6 O 13 electrode couple. Preliminary results indicated a good reversibility, but interfacial polarization was significant.

Sodium/V/sub 6/O/sub 13/ polymer electrolyte cells

Although lithium anodes offer many attractive features such as high energy density and high negative electrode potentials, the advantages may be overshadowed by the disadvantages. The use of sodium anodes may be an attractive alternative therefore that is explored in the present research. Apart from work on the Na/S battery, the investigation of sodium secondary battery systems has been slow because of the stability problems experienced by the sodium anodes in most organic electrolytes. In this paper, the behavior of the cell Na/PEO/sub 8/.NaCF/sub 3/SO/sub 3//V/sub 6/O/sub 13/, operating at 95{sup 0}C is described.

Assessment of thin film batteries based on polymer electrolytes. II. Pulse power density

Abstract The modeling of polymer electrolyte batteries based on prismatic unipolar and bipolar electrode configurations capable of delivering high specific pulse powers are described. The theoretical performance level of this class of rechargeable solid state batteries utilizing polyethylene oxide based solid electrolytes and V6O13 composite cathodes is analyzed; specific pulse powers of about 4 MW/kg are conceivable for a metallized plastic current collector, bipolar electrode design concept.

Assessment on thin film batteries based on polymer electrolytes. III. Specific energy versus specific power

Abstract The feasibility of solid state polymer electrolyte batteries for applications such as the electric vehicle depends on the variation in the performance levels of the specific energy and specific power. In this paper efforts have been centered mainly on rechargeable lithium batteries with electrolyte complexes formed between polyethylene oxide and lithium salts having an ionic conductivity of 10 −4 (Ω cm) −1 and V 6 O 13 insertion cathodes. Prismatic unit cells of variable cathode thickness have been modeled and calculated results indicate that high specific energies (∼200 Wh/kg) and high specific powers (∼700 W/kg) are possible for this battery system utilizing metallic current collectors. Considerably higher values result for low density metallized plastic current collectors.

Insertion reaction of V6O13 electrodes reversibly incorporating divalent cations

Abstract Single crystal V 6 O 13 has been evaluated for the insertion of divalent Zn and Cu ions. Coulometric studies have shown that V 6 O 13 is reversible to both types of cation. A single-phase region exists in the range 0≤ x ≤0.14forZn x V 6 O 13 and 0≤ x ≤0.11forCu x V 6 O 13 . Impedance and galvanostatic relaxation have both revealed that the diffusion coefficients of the divalent cations were of the order of 10 −10 cm 2 /s in the low concentration, single-phase regions. Diffusion rates were significantly reduced at higher concentrations. Impedance measurements have also shown that the kinetics of charge injection dominates the high freqeuncy response for both cations.