The main differences between the two types of batteries is that one is rechargeable (secondary) and one is non-rechargeable (primary). Rechargeable batteries are batteries which consists of reversible reactions which allow them to recharge, or it could get its potential back, by the work done due to the passing of electricity. Secondary cells can charge and discharge many times. Primary cells cannot be reused. The electrochemical reaction is not reversible, so it cannot be used more than once. It’s a cell which converts chemical energy into electrical energy by irreversible chemical reaction.
A battery is composed of many cells and that’s where the storage and discharge take place. Electrochemical cells consist of two electrodes, the space between them is filled with an electrolyte (ionic liquid that conducts electricity). On the right side of the battery there is the anode which makes the electrons flow out of it and the other side is on the left the anode which receives the electrons. The anode undergoes the oxidation reaction and cathode undergoes a reduction reaction.
The chemical reaction at the anode releases the electrons and the cathode absorbs them. When the electrolytes and external electrical circuits provides the electrical path, they connect the anode and cathode. The reactions proceed, and the electrons are released at the anode and travel through the external electrical connection they react chemically until they run out of electrodes so not reactions can take place. This means that in a primary cell that the battery is no longer useful and would have to be disposed. Whereas, in the secondary battery it means that it’s time for the battery to be re-charged. It does this by an external source of direct electrical current which supplies the electrons to the anode which removes them from the cathode, making the chemical reactions into reverse until it is recharged.
The voltage is generated by movement of the electron between the two half cells. For example, zinc-carbon cell, the zinc rod releases electrons and leans Zn2+ within the solution. The negatively charged electrons flow through the external circuit to the copper rod so it can combine with Cu2+ ions so therefore it can form copper atoms. The right hand of the half cell is a position charge which travels through the salt bridge, due to this arrangement it pushes the electrons and ions around it which generates voltage.
Differences between the both:
Primary cells don’t have free-flowing electrolytes so instead of that they have separators which hold the electrolytes inside them this is because they lack quantity of liquid electrolyte for example, batteries are called dry cells whereas, secondary cells contain the liquid electrolyte and they are referred as wet cells.
Some examples of primary cells are batteries used in toys, radios and some electronic products. Whereas, car batteries are standby power sources and they usually are secondary cells. They require a liquid electrolyte. The secondary cells are usually larger than primary cells. Primary cells are less expensive than secondary cells. This is because the construction of primary cells is simpler whereas, secondary cells require additional maintenance.
· Primary batteries can be used in range of applications because they are small and light, so they can be easily carried around they are usually found in toys, watches, radio etc.
· Secondary cells are used in cars as they are rechargeable, and a primary battery won’t last as long as a secondary battery, so they are used in cars etc.
· Primary batteries have to be replaced after a month or two because they have a low life span.
· Secondary cells are Havier in comparison to primary batteries and in most cases bigger as well.
· Primary batteries have a short life time and its overall energy efficiency, single use, disposable, they produce only about 2% of the power used in within their manufacture.
· Secondary batteries have a long life and can be used for around 25 hours but also can be recharged.
· Primary batteries cannot be recharged so they can only be used for a certain amount of time and after that they would have to be disposed.
· Primary batteries don’t have an advantage for disposing.
· Secondary batteries create less chemical pollution as they aren’t many batteries that get disposed in comparison to primary batteries, so therefore, they create less pollution.
· The disposable hazard of disposing primary batteries is that it creates chemical pollution, and this is bad for the environment as it contributes in air pollution and global warming.
· Secondary batteries still create pollution when some are disposed.
· Primary batteries are less expensive in comparison to secondary batteries.
· Secondary batteries have a longer life span as they are rechargeable and can be kept for a long time.
· Primary batteries have a low life span so therefore, they are expensive in a way as they don’t last if a secondary battery.
· Secondary batteries are more expensive compared to primary batteries.
· Primary battery capacity is high e.g. lead-acid capacity % is 35. And an AA battery has a capacity of 2400 (mAh) and the typical drainage is 50 (mA).
· Secondary battery capacity is higher than the primary one for example, silver-zinc has a capacity % of 85. And an AAA has a capacity of 1000 (mAh) and has a typical drainage of 10 (mA).
· Primary battery has a lower capacity in comparison to a secondary bat tery so in terms of which is more efficient it would be secondary battery.
A device which is portable and consists of a secondary battery is an apple iPhone. The phone has a built in battery which is rechargeable and is a lithium-ion battery. They decided to choose lithium as their battery because it charges faster, they also have a long life span (last longer) and they have a high power density for more battery life in a lighter package. The battery uses fast charging to quickly reach 80% of its capacity. It then changes to a slower charging. The time for the battery to reach 80% varies depending on the setting of the device. This combined process allows a person to go out sooner and it also expands the lifespan of the devices battery.
Lithium-ion battery can be charged whenever, at any percentage. The lithium battery works in charge cycles. A complete cycle is when you’ve used an amount that equals 100% of the battery capacity (this doesn’t have to be from one charge). For example, a person may use 75% of their battery capacity one day, then re-charge it overnight. If the person was to use 25% the next day, the total discharge would be 100% and the two days would add up to one charge cycle. The capacity of any other type of battery would demolish after a certain amount of recharging. With lithium-ion batteries, the capacity demolishes slightly with every complete charge. They are designed to hold 80% pf their original capacity for a lot of the capacity for a lot of charge cycles.
The lithium battery is designed to be disposed in an appropriate manner so therefore, apple have an online and in store system where they can take in your device free of charge to dispose the device (battery). They have a system because lithium-ion batteries can be bad for the environment so therefore, apple discharge the batteries in a proper manner. Because the lithium battery is a secondary battery it can recharge several times and they don’t have a disposing hazard as they are carried out by the apple company. The cost of the portable device is expensive because it’s a secondary battery and they are manufactured with care and need more attention in comparison to primary battery so therefore, the phones cost more, but an advantage is that it has many circuit cycles, so the phones are worth the money. Also, the battery isn’t harmful for the environment in terms of when it is being used for example, they do not blow up or self-discharge.
Another portable device is a torch, the best battery for a device would be an AA (alkaline battery), and they are also more common. They are good because they keep their charge for around 4 hours for a non-rechargeable battery that life span is good and appropriate. These batteries have double the energy density in comparison to other batteries such as, carbon batteries. So, these batteries produce the same amount of energy while lasting longer. It has longer shelf-life then batteries with chloride-type electrolyte. This battery also works at low temperatures and its discharge rate is also low. The safety of this battery is also good as it has less impacts on the environment in comparison to other batteries. These batteries are not corrosive or life threatening if it was to be spilled, they are only irritant to the skin if it was to be in contacted with someone (also, it has no special way of disposing the battery). This why most people use these batteries in their torches as it is cost efficient, has low discharge rate, less disposing hazards, long shelf life and many more.