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Cheap glass fiber mats as a matrix of gel polymer electrolytes for lithium ion batteries.

Zhu Y, Wang F, Liu L, Xiao S, Yang Y, Wu Y - Sci Rep (2013)

Bottom Line: Gel polymer electrolytes (GPEs) have been tried to replace the organic electrolyte to improve their safety.However, the application of GPEs is handicapped by their poor mechanical strength and high cost.The results show this gel-type composite membrane has great attraction to the large-capacity LIBs requiring high safety with low cost.

View Article: PubMed Central - PubMed

Affiliation: New Energy and Materials Laboratory (NEML), Department of Chemistry & Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433, China.

ABSTRACT
Lithium ion batteries (LIBs) are going to play more important roles in electric vehicles and smart grids. The safety of the current LIBs of large capacity has been remaining a challenge due to the existence of large amounts of organic liquid electrolytes. Gel polymer electrolytes (GPEs) have been tried to replace the organic electrolyte to improve their safety. However, the application of GPEs is handicapped by their poor mechanical strength and high cost. Here, we report an economic gel-type composite membrane with high safety and good mechanical strength based on glass fiber mats, which are separator for lead-acid batteries. The gelled membrane exhibits high ionic conductivity (1.13 mS cm(-1)), high Li(+) ion transference number (0.56) and wide electrochemical window. Its electrochemical performance is evaluated by LiFePO4 cathode with good cycling. The results show this gel-type composite membrane has great attraction to the large-capacity LIBs requiring high safety with low cost.

No MeSH data available.


Related in: MedlinePlus

Lithium ion conductivity and transference number for the wetted membranes.(a) Impedance plots of the conductivity data at different temperatures and Arrhenius plots of the Celgard 2730 and the gel PVDF-GFM membrane; and (b) Chronoamperometry profiles for the Celgard 2730 and the gel PVDF-GFM membrane at 25°C in block cells using Li metal as both electrodes with step potential of 10 mV.
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f4: Lithium ion conductivity and transference number for the wetted membranes.(a) Impedance plots of the conductivity data at different temperatures and Arrhenius plots of the Celgard 2730 and the gel PVDF-GFM membrane; and (b) Chronoamperometry profiles for the Celgard 2730 and the gel PVDF-GFM membrane at 25°C in block cells using Li metal as both electrodes with step potential of 10 mV.

Mentions: The uptake amount (the main factor for ionic conductivity) for the composite can be up to 132 wt.%, higher than that of Celgard 2730 (90.9 wt.%). This indicates that the ionic conductivity of the gelled composite will be at least at the same order of magnitude as that for the commercial separator. Figure 4a shows the ionic conductivities dependence on temperature for the commercial separator (Celgard 2730) and the gelled PVDF-GFM membrane at the range from 25 to 75°C. The conductivity was calculated from the impedance plots shown in the insets of Figure 4a. Typical impedance plots consist of a high frequency semicircle followed by a low frequency straight line, which correspond to contributions from the bulk/grain boundary and the electrode resistances, respectively. When the current carriers are ions and the total conductivity is the main result of ionic conduction, the plot shows the disappearance of the semicircular portion. The resistance of the bulk electrolyte has been retrieved from the intercept of the straight line on the real axis27. The ionic conductivity of the gel membrane at 25°C is 1.12 mS cm−1 and the value is five times that of the Celgard 2730 saturating with organic electrolyte (0.21 mS cm−1). This presents that the ionic conductivity of the GPEs is above the level for the commercial separator. The dependence of ionic conductivity on temperature can be reasonably fitted by the following equation (1):where A is the pre-exponential factor and Ea is the activation energy. Ea values are 0.014 eV and 0.023 eV for the PVDF-GFM gel electrolyte and Celgard 2730, respectively. That is, the movement of Li+ ions in the gel PVDF-GFM membrane is much easier than that in the Celgard 2730. The electrochemical stability of the gel PVDF-GFM electrolyte (Supplementary Fig. S2) is similar to that of the Celgard 2730, about 4.8 V, which is enough for LIBs. The transference numbers of Li+ ions are 0.27 and 0.54 for the Celgard 2730 and the gel PVDF-GFM membranes, respectively, which were estimated by chronoamperometry (Figure 4b) by comparing the initial and final current values.


Cheap glass fiber mats as a matrix of gel polymer electrolytes for lithium ion batteries.

Zhu Y, Wang F, Liu L, Xiao S, Yang Y, Wu Y - Sci Rep (2013)

Lithium ion conductivity and transference number for the wetted membranes.(a) Impedance plots of the conductivity data at different temperatures and Arrhenius plots of the Celgard 2730 and the gel PVDF-GFM membrane; and (b) Chronoamperometry profiles for the Celgard 2730 and the gel PVDF-GFM membrane at 25°C in block cells using Li metal as both electrodes with step potential of 10 mV.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3824160&req=5

f4: Lithium ion conductivity and transference number for the wetted membranes.(a) Impedance plots of the conductivity data at different temperatures and Arrhenius plots of the Celgard 2730 and the gel PVDF-GFM membrane; and (b) Chronoamperometry profiles for the Celgard 2730 and the gel PVDF-GFM membrane at 25°C in block cells using Li metal as both electrodes with step potential of 10 mV.
Mentions: The uptake amount (the main factor for ionic conductivity) for the composite can be up to 132 wt.%, higher than that of Celgard 2730 (90.9 wt.%). This indicates that the ionic conductivity of the gelled composite will be at least at the same order of magnitude as that for the commercial separator. Figure 4a shows the ionic conductivities dependence on temperature for the commercial separator (Celgard 2730) and the gelled PVDF-GFM membrane at the range from 25 to 75°C. The conductivity was calculated from the impedance plots shown in the insets of Figure 4a. Typical impedance plots consist of a high frequency semicircle followed by a low frequency straight line, which correspond to contributions from the bulk/grain boundary and the electrode resistances, respectively. When the current carriers are ions and the total conductivity is the main result of ionic conduction, the plot shows the disappearance of the semicircular portion. The resistance of the bulk electrolyte has been retrieved from the intercept of the straight line on the real axis27. The ionic conductivity of the gel membrane at 25°C is 1.12 mS cm−1 and the value is five times that of the Celgard 2730 saturating with organic electrolyte (0.21 mS cm−1). This presents that the ionic conductivity of the GPEs is above the level for the commercial separator. The dependence of ionic conductivity on temperature can be reasonably fitted by the following equation (1):where A is the pre-exponential factor and Ea is the activation energy. Ea values are 0.014 eV and 0.023 eV for the PVDF-GFM gel electrolyte and Celgard 2730, respectively. That is, the movement of Li+ ions in the gel PVDF-GFM membrane is much easier than that in the Celgard 2730. The electrochemical stability of the gel PVDF-GFM electrolyte (Supplementary Fig. S2) is similar to that of the Celgard 2730, about 4.8 V, which is enough for LIBs. The transference numbers of Li+ ions are 0.27 and 0.54 for the Celgard 2730 and the gel PVDF-GFM membranes, respectively, which were estimated by chronoamperometry (Figure 4b) by comparing the initial and final current values.

Bottom Line: Gel polymer electrolytes (GPEs) have been tried to replace the organic electrolyte to improve their safety.However, the application of GPEs is handicapped by their poor mechanical strength and high cost.The results show this gel-type composite membrane has great attraction to the large-capacity LIBs requiring high safety with low cost.

View Article: PubMed Central - PubMed

Affiliation: New Energy and Materials Laboratory (NEML), Department of Chemistry & Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433, China.

ABSTRACT
Lithium ion batteries (LIBs) are going to play more important roles in electric vehicles and smart grids. The safety of the current LIBs of large capacity has been remaining a challenge due to the existence of large amounts of organic liquid electrolytes. Gel polymer electrolytes (GPEs) have been tried to replace the organic electrolyte to improve their safety. However, the application of GPEs is handicapped by their poor mechanical strength and high cost. Here, we report an economic gel-type composite membrane with high safety and good mechanical strength based on glass fiber mats, which are separator for lead-acid batteries. The gelled membrane exhibits high ionic conductivity (1.13 mS cm(-1)), high Li(+) ion transference number (0.56) and wide electrochemical window. Its electrochemical performance is evaluated by LiFePO4 cathode with good cycling. The results show this gel-type composite membrane has great attraction to the large-capacity LIBs requiring high safety with low cost.

No MeSH data available.


Related in: MedlinePlus