Voltaic cell + battery in series

  • #1
Manganese
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TL;DR Summary
Would connecting a battery in series with a voltaic cell accelerate the rate of the redox reaction of the cell?
Hello,
I wanted to know if connecting a battery in series with a voltaic cell would increase the rate of the redox reactions.

Let's take the simplest example of a voltaic cell constituted by a Zn/Zn2+ half-cell connected to a Cu/Cu2+ half-cell. When the circuit is closed, the Zn electrode will get corroded and will dissolve in Zn2+, while the Cu2+ ions in the other half-cell will get reduced to Cu.

What I wanted to know is, if I connect a battery in series with this voltaic cell (maintaining the same current direction), the potential difference should stack (if the Zn/Cu cell has a potential of 1.10 V, connecting a 3V battery in series should bring it to 4.10 V).

Will this potential increase somehow affect the rate of the redox reaction? Or the increase of the potential only affects the thermodynamics of the process (as in, it's just higher voltage) but the kinetics are unaffected? And also, would connecting a battery in series with this type of voltaic cell result in shorting the battery? I know they are getting discharged, but would this be happening at a fast rate or the voltaic cell acts as some sort of resistance?

I drew a sketch
voltaic cell + battery.png
 
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  • #2
In general - yes, but if the voltage gets too high you can start unwanted side reactions (like water hydrolysis).
 
  • #3
Manganese said:
I wanted to know if connecting a battery in series with a voltaic cell would increase the rate of the redox reactions.
An "electric battery" is a stack of electrochemical cells, working together, usually in series, to produce a higher voltage than a single cell. In the same sense, a "gun battery" is composed of several guns, that aim to work together.

The rate of the redox reactions can be increased only by increasing the current flowing through the cell. That can be done by reducing the circuit load resistance. That is Ohm's law.

For a fixed load resistance, having more cells in series would increase the current and the rate of reaction. Again, that is Ohm's law.

The circuit resistance includes the internal resistance of the battery. Heating the battery may reduce the battery internal resistance, and so increase the rate of reaction.
 
  • #4
Manganese said:
Will this potential increase somehow affect the rate of the redox reaction?
Yes, around the 'normal' currents and voltages of the cells used.
But once it's out of the 'normal' range and boiling or electrolysis happens, it may become (very) complicated.
 

FAQ: Voltaic cell + battery in series

What is a voltaic cell?

A voltaic cell, also known as a galvanic cell, is an electrochemical cell that converts chemical energy into electrical energy through spontaneous redox reactions. It consists of two different metals connected by a salt bridge or a porous disk between individual half-cells.

How does connecting a voltaic cell and a battery in series affect the overall voltage?

When a voltaic cell and a battery are connected in series, their voltages add up. This means the total voltage of the series connection is the sum of the voltages of the voltaic cell and the battery. For example, if a voltaic cell has a voltage of 1.5V and the battery has a voltage of 3V, the total voltage will be 4.5V.

Can a voltaic cell and a battery in series provide more current?

Connecting a voltaic cell and a battery in series does not increase the current capacity; it increases the voltage. The current provided by the series combination will be limited by the component with the lowest current capacity. Therefore, the combined current will be the same as the current capacity of the weakest component.

What are the potential issues when connecting a voltaic cell and a battery in series?

Potential issues include mismatched internal resistances, which can lead to inefficiencies and energy losses. Additionally, if the voltaic cell and the battery have significantly different capacities, one may deplete faster than the other, leading to potential damage or reduced lifespan of the components.

How can you ensure safe operation when connecting a voltaic cell and a battery in series?

To ensure safe operation, it is important to match the voltage and current ratings of the voltaic cell and the battery as closely as possible. Use protective components such as fuses and diodes to prevent overcurrent and reverse polarity. Regularly monitor the voltage and current to ensure they remain within safe limits.

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