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Electrolyte Essay

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1.1 ELECTROLYTE
Electrolyte can be defined as the aqueous or molten substances which when dissolved in a solvent dissociates into ions and can transmit negatively charged ions.
Types of Electrolyte:
Depending upon the state of electrolyte it can be broadly categorized in two types.
1. Liquid electrolyte
2. Solid electrolyte

Liquid electrolyte:
When a miscible salt is completely dissolved in liquid solvent to dissociate positive and negative charged ions, then this mixture is called liquid electrolyte.
For example
HClH++Cl-
Most common ions in an electrolyte are generally Na+, K+, Ca2+, Mg2+ etc.
Solid Electrolyte:
The solid having high electric (ionic) conductive are called solid electrolyte. In general the conductivity of the electrolyte lies in between 10-6 to 10-1 s/cm range.
To be useful solid electrolyte some essential features must be there like,
 It has high ionic conductivity ranging from (10-1 to 10-4 s cm-1)
 Low electron conductivity.
 Principal charge carrier must be ion.
 Low activation energy (Ea < eV).

1.2 SOLID ELECTROLYTE OVER LIQUID ELECTROLYTE:
Through liquid electrolyte have much wider range of utilization in different application (like Li ion, Li metal batteries, Double layered capacitor, Sensors etc.) it has some disadvantages also. These are

a. It has a limited temperature range.
If the liquid electrolyte consists of water as a solvent we cannot use it above or below 100° and 0°C as its boiling point and freezing point respectively. Similarly all liquid has their own boiling and freezing temperature beyond electrolyte ceases to work.
b. Leakage of electrolyte (grassing).
Some batteries consists of harmful toxic acids and it may have threats of leakage because of its liquid state. This is called gr...

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...lica) are the compounds added to the polymer electrolyte to form composite polymer electrolyte or composite ceramic electrolyte.
The main advantages of adding such kind of electrochemically inert filler are following
• At low temperature, to enhance the ionic conductivity.
• Improve the stability at cathode at anode and cathode.

1.8 WHY TO CHOOSE PVDF?
Up to present date there are many polymer hosts [1] have been discovered and some examples are
 Poly(ethelene Oxide)(PEO)
 Poly(propylene Oxide) (PPO)
 Poly(acrylonitrile) (PAN)
 Poly(methyl methacrylate) (PMMA)
 Poly(Vinyl chloride) (PVC)
 Poly(Vinyliden fluoride) (PVdF)
 Poly(Vinyliden flouride)- Hexa fluoro propylene(PVdF- HFP)

All polymer host has some major advantages for which their application in electrochemical devices are still continuing. Also these polymer have some disadvantages and to improve the
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