The Battery – Cathodes, Anodes, and Electrodes (Part 2 of 2)!

In part 1 of “The Battery – Cathodes, Anodes, and Electrodes” we discussed how engineers manufacture disequilibrium to create free negative electrons so that the positive atoms will attract the electrons at the positive electrode, thereby creating an electron flow. We spoke about electrodes and their function in receiving electrons, and we spoke about the how a direct current is created in a battery. Now in part 2 of this report I will look closer at the electrodes and their effect on the flow of electrons.

Collectively the anode and the cathode are called the electrodes. What is positve and what is the negative terminal. It would be great to simply say that the anode is negative and the cathode is positive, however, that is not always the case. Somtimes the opposite is true depending on battery technology. Moving past this debate the positive electrode can be a lithium cobalite composite (LiCoO2) and the negative electrode can be a carbon-graphite composite.

If we can define an anode we would say that the anode is the electrode at which electrons come up from the battery cell and where oxidation occurs. One side bar is that battery manufacturers in the United States regard the anode as the positive electrode, even though that is technically incorrect, however it does help resolve the problem of which electrode is the anode in a rechargeable cell (or secondary cell) which battery manufactures work with daily.

The cathode on the other hand could then be defined as the electrode at which electrons enter the cell and reduction occurs.

One point that was a challenge for me to grasp was that the each electrode may become either the anode or the cathode depending on the flow of the electrons. In part 1 of this report we learned that positive atoms attract electrons from negative charged atoms to balance the positive atoms. The attraction creates an electron flow, flowing at a speed of 62,000,000,000,000,000,000 electrons per second (62 quintillion electrons per second)! These electrons flow on ions from the anode–to–cathode outside of cell and from cathode–to–anode inside a cell, which results in two types of current [a negative ion (anion) flow and positive ion (cation) flow. The two currents flowing from anode to cathode result in a network of electron flow.

As mentioned earlier the positive electrode can be a lithium cobalite composite (LiCoO2) and the negative electrode can be a carbon-graphite composite. But what is key is that in commercial battery cells, the cathode’s active material is a litiated transition-metal oxide such as lithium cobalt oxide. Because lithium is more electropositive then hydrogen, the electrolyte must be nonaqueous and aprotic. A representative formulation is a solution (1:1 by volume) of ethylene carbonate and propylene carbonate containing a suitable lithium salt such as lithium hexaflourophosphate, LiPF6, which raises the conductivity of the electrolyte. A separator of electrolyte, made of polyolefin such as micropourous polypropylene, is placed between the electrodes for safety. If the electrolyte temperature exceeds a certain value the separator melts and current flow ceases. The cells reaction is the formation of lithium cobalt oxide.

From part 1 and part 2 of “The Battery – Cathodes, Anodes, and Electrodes” we have larned that at work inside your battery is some really incredible activity – a power source that is really rather marvelous when considered thoughtfully.

Until next time, Dan Hagopian
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The Battery – Cathodes, Anodes, and Electrodes (Part 1 of 2)!

A battery as we know it is a device that stores chemical energy and through an electrochemical process (electromotive force) converts the stored chemical energy into electric energy via a direct current voltage. The chemical conversion is a process of chemical change created by adding or losing chemical substances (electrons, oxygen, lithium etc.) inside the battery and used by a connecting device (i.e. PDA, iPod, Digital Camera).

A battery cell is the most basic electrochemical unit and often time cells are stacked on top of one another to meet a specific energy design or need, however, when we are speaking of battery cells we refer to them as a battery whether there is one cell, three, or more in a series.

Within each battery cell are three basic components: the anode, the cathode, and an electrolyte solution. Just to be clear every battery design does indeed have more components contained in the battery then the three listed above, however, the electrodes and the electrolyte are the very basic components of all batteries. In this 1of 2 article report however we are going to focus specifically on the cathode and the anode, commonly referred to as the electrodes.

Batteries power devices by the creation of direct electrical current drawn from the flow of electrons, flowing back and forth between the electrodes. The basic format is that electrons collect on the negative electrode, when a substance (i.e a wire, an electrolyte) is placed as a separator between the negative electrode and the positive electrode the electrons flow (are drawn) to the positive electrode. This flow creates a current. The electron current, or electricity, can then be directed to a device and used as a power stream.

The reason why electrons flow is part of the atomic design. Electrons spin around the center, or nucleus, of atoms, in the same way the earth spins around the sun. The nucleus is made up of neutrons and protons. Electrons contain a negative charge, protons a positive charge. Neutrons are neutral — they have neither a positive nor a negative charge.

There are many different kinds of atoms, one for each type of element. An atom is a single part that makes up an element. There are 118 different known elements. The mass accumulation of elements makes up every thing we can see, touch, hear, and smell (elements are even in things we can’t see).

Each atom has a specific number of electrons, protons and neutrons. But no matter how many particles an atom has, the number of electrons usually needs to be the same as the number of protons. If the numbers are the same, the atom is called balanced, and it is very stable.

Some kinds of atoms have loosely attached electrons. An atom that loses electrons has more protons than electrons and is positively charged. An atom that gains electrons has more negative particles and is negatively charge. A "charged" atom is called an "ion."

The very nature of a positive atom is that a positive atom attracts electrons from negative charged atoms to in effect balance the positive atoms. Why, not sure, and for this article not pertinent. What is necessary to know is that the flow of electrons to positive charged atoms is essential for a direct electrical current.

You see electrons can be engineered to move from one atom to another. When those electrons move between the atoms, a current or flow of electricity is created. The electrons move from one atom to another in a "flow." One electron is attached and another electron is lost. This creates a continual equilibrium amongst the atoms.

Engineers manufacture disequilibrium to create free negative electrons so that the positive atoms will attract the electrons at the positive electrode, thereby creating an electron flow or electrical current. When electrons move from atom to atom a current of electricity is created. This is what happens in a piece of wire. The electrons are passed from atom to atom, creating an electrical current from one end to other end.

Inside the battery itself, is a chemical reaction that produces the electrons. If the electrons are not moving then the battery can sit on the shelf for a year. Once the chemical is activated and the flow of electrons takes place, even for a moment then the loss of power begins and there is no stopping it. This is why you never want to buy a used battery.

Until next time -  Dan Hagopian,
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