How do Electric Double Layers Work?

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Discussion Overview

The discussion centers around the concept of electric double layers, particularly in relation to their behavior in capacitors and the conditions required for discharging. Participants explore the mechanisms of ion interaction, energy requirements for discharging, and the role of dielectric materials.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant describes the electric double layer as consisting of two types of ions, with one type adhering to the surface and the other to that ion layer, questioning what prevents discharging at their contact area.
  • Another participant explains that discharging ions necessitates energy, referencing electrolysis and the threshold voltage required to initiate it, suggesting that a small voltage could lead to significant ion neutralization if conditions allowed.
  • A question is posed regarding why connecting the two sides of a capacitor with electrodes is sufficient for discharging, rather than the two layers simply touching.
  • A later reply clarifies that if the plates of a capacitor touch, it will either discharge or not charge at all if they are already in contact when power is applied, emphasizing the importance of dielectric materials in maintaining separation between the plates.

Areas of Agreement / Disagreement

Participants express differing views on the mechanisms of discharging and the role of voltage thresholds, indicating that multiple competing perspectives remain without a clear consensus.

Contextual Notes

Some assumptions about the behavior of ions and energy requirements are not fully explored, and the discussion does not resolve the complexities of the interactions within electric double layers or capacitors.

Johnleprekan
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In an electric double layer, there are two types of ions. The first ion type is stuck to the surface and the second one is stuck to that ion layer. They are both of different charges, but are in close contact with each other. So what prevents this from discharging at the contact area?
 
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Discharging ions requires energy. For example if you stick two pieces of metal into water and apply a voltage you can only get electrolysis if the voltage is above a threshold. Otherwise you would violate conservation of energy. How many ions get neutralized depends on current times time i.e. charge. If a very tiny voltage was sufficient you could neutralize a huge amount of ions with a very small amount of energy.
 
In the case of a capacitor, why is connecting the two sides with electrodes sufficient to discharge this instead of the two layers touching?

The two layers being the capacitor that is and connecting this to a load.
 
If the two plates of a capacitor touch it will discharge, or not charge at all if touching when power is applied. Shorted plates are just that; a short. This is the key reason for the dialectic material it keeps the plates well separated both physically and electrically.
 

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