The advancement of human civilization can be measured by the need to generate energy efficiently. All the most remarkable achievements have been around this notion. From creating massive-yield atomic bombs to smartphones, humanity has always sought to use power to its advantage. However, that need threatens our existence if we don’t find ways to harness that energy cleanly. To that end, batteries are crucial to turning things around.
Before perfecting our battery technology, it is essential to understand how its components work. A critical factor that many people often overlook is the electrolyte. Throughout this guide, you’ll learn about this valuable chemical and the best electrolyte for batteries.
What Is an Electrolyte?
Unlike the electrolytes you need to filter water or keep your blood flow stable, battery electrolytes are responsible for transferring electrons and ions internally as the battery charges or discharges. Without an electrolyte, the circuit would remain open even as the electrodes are connected, as the internal chemical reaction won’t occur.
Each type of battery uses a specific electrolyte since they undergo different chemical reactions. It is usually filled in a way so that it remains in contact with both electrodes. At times, it can even fulfill the role of a separator for volatile compounds.
How Do Electrolytes Work?
To understand the electrolyte’s working in detail, let us consider the sulfuric acid solution used in lead-acid batteries. The mix has sulfate ions that react with the lead at the anode to create lead sulfate. The hydrogen ions create water by combining with oxygen from the lead oxide. The cathode breaks down and lets solid lead particles deposit on the anode.
The process mentioned above occurs in a discharging battery. When in a charging state, the process is reversed.
Types of Electrolytes
Depending on their type, each battery utilizes a different kind of electrolyte. Some of the most common examples are mentioned below.
Most lead-acid batteries work with lead and lead oxide electrodes dipped in concentrated sulfuric acid. The solution has a 37% concentration of pure acid, with the rest being distilled water. That is critical because any impurities can interfere with the balance of the reaction in the cells.
As the battery discharges, the concentration of lead sulfate in the electrolyte increases. Therefore, a current is required to break it down into lead and sulfate ions. Yet, the current flow also works on reducing the water concentration through electrolysis. That is why you require constant water refills to keep the concentrations consistent. But that also dilutes the electrolyte, which is why lead-acid batteries eventually die out after a few years of extensive use.
Popularly used as button cell batteries, Ni-Cd cells use a potassium hydroxide solution as an electrolyte. It has a 20-35% concentration by weight dissolved in distilled water. The nickel oxide converts into nickel-oxyhydroxide, whereas the cadmium oxidizes, granting electrons to the circuit. As the battery discharges, the nickel-oxyhydroxide consumes the electrons to transform back into nickel hydroxide as the cadmium ions reduce to cadmium hydroxide ions, with water being the by-product. The process gets reversed when the battery charges up.
Because the cadmium hydroxide is less volatile, Ni-Cd batteries can undergo thousands of cycles before being made redundant. Still, the high cost of manufacturing the chemicals deems the batteries expensive to apply on a large scale.
In order to save on mining nickel and cadmium, lithium-ion batteries are the best option for high-density batteries available today. They are used in most electric vehicles and electronic gadgets. Lithium-ion batteries use lithium hexafluorophosphate dissolved in organic salts. Thus, the batteries can be compact since they don’t use incompressible fluids like water.
The lithium graphite ions at the anode break down into lithium ions and graphite to supply electrons. Those lithium ions displace the ones in the salt, which further transfer to the cathode. That is when the cobalt oxide combines with the lithium ions consuming the electrons to form lithium cobalt oxide. It is a relatively swift process, which is why thermal stability is an issue with lithium-ion batteries.
Solid State Batteries
Solid-state batteries constitute an experimental technology that stabilizes heat output from the electrolyte, which is why they use lithium thiosulfate. The thiosulfate ions cool down the battery by transferring the lithium ions from within the solvent instead of reacting with the separator walls. While the effectiveness of the electrodes is still under development, the electrolyte shows a lot of promise, as it can be manufactured on a large scale within reasonable costs.
Best Electrolyte for Battery
Technically, the best electrolyte for a battery is an inorganic salt mixed with organic solvents that provide high ionic conductivity and thermal stability. Therefore, the best option is lithium thiosulfate. The solvent can last for years without replacement and can be manufactured relatively inexpensively compared to its quasi-solid-state alternatives. Moreover, it is much safer to use than acidic solutions popular today.
Nevertheless, concentrated acid solutions are most suitable for car and inverter batteries today due to the prevalent use of lead-acid batteries. That is why you are better off stocking up on concentrated sulfuric or nitric acid if you want to replace electrolytes in your batteries.
Precautions To Exercise Around Electrolytes
Even though the batteries seal the chemicals to minimize hazards, you should maintain a few precautions when dealing with electrolytes. Some of the crucial steps include the following.
- Use gloves and goggles when handling electrolytes. If you expect to be around organic chemicals, it is also advised to wear gas masks.
- Always store and refill electrolytes in an isolated location, away from individuals or pets.
- Never dispose of used electrolytes in regular trash bins. Neutralize them and take them to special chemical disposal facilities.
- Have a first aid kit and a dash of vinegar or baking soda in the vicinity, depending on the electrolyte’s nature.
- Always wear thick boots, jeans, and full-sleeved shirts when dealing with electrolytes. A sealed chemical suit is an ideal choice.
- Pour acids or other liquid-based electrolytes from insulated containers. Never touch the container if you observe steam or bubbles on the surface.
Electrolytes play a monumental role in determining the nature of any battery. Solid-state electrolytes are the best electrolyte for batteries, thanks to their high conductivity, safety, and thermal stability. Still, it might be years before they become part of everyday applications, so it is best to go with concentrated sulfuric acids for the time being.