Preparation and electrochemical properties of polymer Li-ion battery reinforced by non-woven fabric

Abstract

A polymer electrolyte based on poly(vinylidene) fluoride-hexafluoropropylene was prepared by evaporating the solvent of dimethyl formamide, and non-woven fabric was used to reinforce the mechanical strength of polymer electrolyte and maintain a good interfacial property between the polymer electrolyte and electrodes. Polymer lithium batteries were assembled by using LiCoO₂ as cathode material and lithium foil as anode material. Scanning electron microscopy, alternating current impedance, linear sweep voltammetry and charge-discharge tests were used to study the properties of polymer membrane and polymer Li-ion batteries. The results show that the technics of preparing polymer electrolyte by directly evaporating solvent is simple. The polymer membrane has rich micro-porous structure on both sides and exhibits 280% uptake of electrolyte solution. The electrochemical stability window of this polymer electrolyte is about 5.5 V, and its ionic conductivity at room temperature reaches 0.151 S/m. The polymer lithium battery displays an initial discharge capacity of 138 mA·h/g and discharge plateau of about 3.9 V at 0.2 current rate. After 30 cycles, its loss of discharge capacity is only 2%. When the battery discharges at 0.5 current rate, the voltage plateau is still 3.7 V. The discharge capacities of 0.5 and 1.0 current rates are 96% and 93% of that of 0.1 current rate, respectively.

Keywords

polymer electrolyte / Li-ion battery / poly(vinylidene) fluoride-hexafluoropropylene / ionic conductivity

References

[1] ZhangS. S., ErvinM. H., XuK., et al.. Microporous P(AN-MMA) membrane as a separator of rechargeable lithium battery[J]. Electrochimica Acta, 2004, 49(20): 3339-3345

[2] KimH. S., KunK. S., ChoB. W., et al.. Electrochemical and physical properties of composites polymer electrolyte of PMMA and PEGDA[J]. Journal of Power Sources, 2003, 124(1): 221-224

[3] KimK. M., KoJ. M., ParkN. G., et al.. Characterization of P(VDF-HFP)-based polymer electrolyte filled with rutile TiO₂ nanoparticles[J]. Solid State Ionics, 2003, 161(1): 121-131

[4] KimD. W., KimY. R., ParkJ. K., et al.. Electrical properties of the plasticized polymer electrolytes based on acrylonitrile-methacrylate copolymers[J]. Solid State Ionics, 1998, 106(2): 329-337

[5] DongD. Y., DaejonY.. Cycling performances of Li/LiCoO₂ cell with polymer-coated separator[J]. Electrochimica Acta, 2004, 50(2/3): 323-326

[6] SongM. K., KimY. T., ChoJ. Y., et al.. Composed polymer electrolytes reinforced by non-won fabric[J]. Journal of Power Sources, 2004, 125(1): 10-16

[7] XiJ. Y., TangX. Z.. Enhanced lithium ion transference number and ionic conductivity of composite polymer electrolyte doped with organic-inorganic hybrid P123@SBA-15[J]. Chemical Physics Letters, 2004, 400(1): 68-73

[8] LiuG., KeinhoutM., BakerG. L.. Nanoscale lithium ion conducting polyethylene oxide with self-attached insulating layers[J]. Solid State Ionics, 2005, 175(4): 721-724

[9] WuC. G., LuM. I., ChuangH. J.. PVDF-HFP/P123 hybrid with mesopores: a new matrix for high-conducting, low-leakage porous polymer electrolyte[J]. Polymer, 2005, 46(20): 5929-5938

[10] WangZ. L., TangZ. Y.. Characterization of the polymer electrolyte based on the blend of PVDF-HFP and PVP for lithium battery[J]. Materials Chemistry and Physics, 2003, 82(1): 16-20

[11] SongJ. Y., WangY. Y., WangC. C.. Review of gel-type polymer electrolytes for lithium batteries[J]. Journal of Power Sources, 1999, 77(2): 183-197

[12] KumK., SongM., KimY. T., et al.. The effect of mixed salts in gel-coated polymer electrolyte for advanced lithium battery[J]. Electrochimica Acta, 2004, 50(2/3): 285-288