Whether you are looking for batteries for your home backup, solar installation, car batteries or any other use, there are several types of batteries that come to mind. The most commonly used batteries are lithium-ion batteries and lead-acid batteries, as they are some of the best choices available. Both lead acid batteries and lithium-ion batteries are secondary batteries meaning that they can be used and recharged, as rechargeable batteries.
All batteries have their pros and cons based on their limitations and mode of use. However, they will both serve similar purposes. It is important to bear in mind that lithium-ion batteries are a newer technology aimed at tackling the shortcomings of lead-acid batteries.
Aside from the chemical composition and build differences, both batteries differ in other ways. The main differences are cost and performance, with lead batteries being the less expensive option and lithium-ion being preferred as the more efficient choice. Although lithium-ion batteries are replacing lead-acid batteries in most applications, lead-acid batteries are still widely used.
As battery storage becomes increasingly popular from solar energy systems to electric vehicles, it is important to understand how different batteries work. And understand which choice best suits your need. As their names imply, lead acid batteries use an acid electrolyte and a lead electrode whilst lithium batteries use lithium metal.
Let us look at a little bit of the chemistry….
How do lithium ion and lead acid batteries work?
Primarily, lead-acid and lithium-ion batteries work on the same general principle based on electrochemistry. Thus, stores charge and release electrons, discharge, to produce electricity through an electromechanical reaction that happens between the electrolyte and the electrodes.
Structurally, lead-acid and lithium-ion batteries consist of the following parts:
- Electrodes: Cathode ( ) and Anode (-)
- An electrolyte
- Membrane separator
The batteries are similar in structure and working principle and the materials used for each component vary vastly. Due to this difference in chemical composition, the internal workings and reactions happening inside are also different. However, the chemical reactions inside are reversible making the batteries rechargeable.
Lead acid battery
For lead acid batteries both the anode and cathode are lead compounds while sulfuric acid is used as an electrolyte. During the process of discharge when the battery is in use, the sulfate ions in the sulfuric acid bond with the lead, releasing electrons.
On the other hand, when charging the battery, the process is reversed and the sulfate ions are released back into the acid.
Lithium-ion battery
In comparison, lithium-ion batteries use a more complex electrochemical process to produce energy, basically moving the ions from one electrode to the other.
Lithium is present in both the anode and the cathode. The electrolyte transports positively charged lithium ions from the anode to the cathode through the separator (and vice versa).
Free electrons are produced in the anode when these ions flow through the battery, producing a charge at the positive current collector. After reaching the powered device, the electric current travels from the collector back to the negative current collector where it is collected.
How does a Lithium-Ion battery compare to a Lead acid battery?
With the differences arising from the electrochemical process and the chemistry of the batteries, also comes the difference in performance, cost, reliability and efficiency. Thus, lithium-ion batteries and lead-acid batteries are suited for different operations and applications.
Here are a few head-to-head comparisons that can help determine the choice of battery to use for a certain application. In most cases, the lithium-ion battery is considered a better choice due to its more advanced technology, offering better reliability, efficiency, and energy output among other advantages.
1. Cost
The cost of an item is one of the key motivations in determining the item among any range of choices. Although often the choice is also influenced by other factors such as capacity, effectiveness and application. In this category, lead acid batteries outperform lithium-ion batteries, as they are cheaper and more economical. Since a lead acid battery system can cost thousands of dollars less compared to a similarly configured lithium-ion pack.
The complexity, materials and cost of manufacturing lithium-ion batteries are higher compared to lead acid batteries. This means that lead-acid batteries are easier and more cost-effective. The affordability per large current requirements at low cost makes lead acid batteries a prevalent choice for large-scale stationary applications.
While lead-acid batteries are often less expensive to purchase and install than lithium-ion batteries, the lifetime value of a lithium-ion battery balances the scales. Lithium-ion batteries are the preferable option in this situation due to their cost in relation to power and efficiency.
2. Capacity and Energy Density
When it comes to batteries it is important to weigh the capacity and the energy density of the choices. Capacity can be defined as the measure of the amount of energy that can be stored in a battery and later discharged on demand. Capacity is a variable factor from the battery to battery depending on the manufacturer, form factor and even battery models.
On the other hand, energy density is the measure of how much energy can be held within a certain space. From a chemical point of view, a battery's capacity and or energy density refers to the product of the working voltage of the electrochemical process and the total charge of the transported ions (Li or H ). The lightest metal on earth is lithium. Lithium has 29 times more atoms per kilogram than lead. In addition, Lithium-Ion has a working voltage of 3.2V as opposed to lead acid’s -2V. As a result, a lithium battery weighs around 1 kg less than a lead-acid battery. Lead acid batteries typically provide between 80 and 90 watt-hours per litre (Wh/L), while lithium-ion batteries provide around 450-650 Wh/L.
Thus, compared to lead acid batteries, lithium-ion batteries have a far greater capacity for energy storage while also occupying the same minimal space or smaller.
3. Efficiency
Efficiency can be described for short as the ratio of input to output, for batteries, this would refer to how well a battery discharges energy after charging. In application, as much as solar panel efficiency in the solar installation or motor efficiency in electric cars is important battery efficiency is an important metric to consider when choosing a battery.
As the majority of lithium-ion batteries have an efficiency of 95% or higher, 95% or more of the energy they store may actually be used. Lead acid batteries, on the other hand, see efficiency closer to 50 to 85 percent. Because lithium-ion batteries are so much more efficient, it is possible to utilize a smaller battery to get the same effects as a bigger lead-acid battery.
Better battery efficiency normally indicates that a battery can charge faster, has good discharge cycles and has better battery capacity.
4. Depth of Discharge
In batteries, the depth of discharge, DOD, is understood as the percentage of the battery's stored energy that can be drained safely without causing damage to the battery cells. The differences between the battery's depth of discharge indicate how much usable capacity of a battery is possible. This is highly dependent on the battery’s chemistry.
More than 85% of a lithium-ion phosphate battery's overall capacity is frequently utilized during routine use. Over-discharging lead acid batteries by more than half are not advised. The chemistry of a lead acid battery means that if it is depleted more than 50%, it will probably have a shorter lifespan.
With the increased energy density of lithium-ion technology noted above, as well as the superior depth of discharge made available by the technology, lithium-ion batteries offer an even larger effective capacity than lead-acid alternatives.
5. Lifespan
As batteries age, they degrade over time and lose their effective capacity. With each time a battery is charged and discharged, that counts as a cycle. Normally all batteries have a limited number of charge-discharge cycles. This indicates the number of times that they can function optimally.
One of the key distinctions between lithium-ion and lead-acid batteries is how many cycles each battery can last. Lithium-ion batteries have a substantially longer life cycle than the other two varieties.
A lithium-ion battery can endure over 1,000 charging cycles with regular use and good maintenance. This is far longer than lead acid batteries' lifespan, especially when you take into account the increased energy density of lithium batteries.
6. Weight / Size
In some particular applications, the issue of battery weight is very important. Lead acid batteries' main flaw is their weight. In contrast to lithium-ion batteries, which are also available in coin size, it is large and takes up more room. Compared to lead-acid batteries, lithium-ion batteries are roughly ten times lighter.
There is a significant weight difference between the two batteries of equivalent strength since a smaller lithium-ion phosphate battery can be used to deliver the same amount of energy as a larger lead-acid battery. Lithium-ion phosphate batteries are a great option for portable devices like medical computer carts because of this.
7. Charging speed
Depending on the battery's size, a lithium-ion battery can be fully charged in 3 hours or as little as a few minutes, as opposed to a lead-acid battery, which can take up to 10 hours. As lithium-ion batteries can tolerate greater current rates, they can be charged more quickly than lead-acid batteries. This is crucial for time-sensitive applications involving more frequent use and shorter rest periods for vehicles.
In EVs for example, where the batteries need to be supercharged lithium-ion batteries are the best choice as with efficient cooling this can be achieved. However, in applications such as wind or solar harvesting for power grids faster charging speeds may not be much of a concern and lead acid batteries can be used.
8. Safety
Although a rarely discussed difference, like any other electrical equipment or energy storage, there is a risk associated with the batteries. The chemical compounds and materials used in these units are not risk-free and although rare accidents happen.
Due to their massive energy storage capacity, lithium-ion phosphate batteries have a risk of exploding. Lithium-ion batteries have a lot more energy storage capacity; nevertheless, if all of the energy is discharged at once, the battery may explode. Even if it's uncommon, it nevertheless happens. Explosions frequently result from a short circuit brought on by poor design or quality control, though they can also spontaneously ignite when exposed to excessive heat.
Also dangerous are lead acid batteries. The battery's highly corrosive acidic electrolyte can damage people who are exposed to it and damage surfaces. Similar to this, lead acid batteries have the potential to emit highly toxic hydrogen sulfate gas, which has the odour of rotten eggs and is extremely corrosive, combustible, and lethal.
Considering the risks connected to each type of battery, mishaps are infrequent and are usually brought on by misuse of batteries or subpar manufacturing or storage techniques. Both battery types are typically used and are regarded as safe.
Applications of Lead Acid Batteries and Lithium-ion batteries
Although the application of lead acid batteries and lithium-ion batteries are fairly similar, the choice of the preferred batteries depends on a host of considerations. Depending on the features, requirements and budget. If we have to make a direct comparison between the applications of lead-acid batteries and lithium-ion batteries, due to their size, lead-acid batteries may only be used in heavy applications. Moreover, extra room is needed to accommodate it.
In autos, power storage devices like UPS systems, maritime applications, and other things, lead-acid batteries are employed as ignition power sources. Despite their size, these batteries are ideal for high current-drain applications such as massive grid-scale power systems and emergency supplies for ships. For this size, their size and bulk do not impede their application and can serve as large reserves of power at a lesser cost.
On the other hand, lithium-ion batteries come in a wide range of dimensions and capacities. As a result, they have many different uses. Mobile phones and laptops are where lithium-ion batteries are most often used. Nowadays, solar power and the operation of electric cars are the most common uses of lithium-ion batteries. These days, practically all portable programs use them. Due to their efficiency, high energy density and small-size lithium-ion batteries can pack large amounts of power compared to any other reserve.
Why choose a lead acid battery vs a lithium-ion battery?
Both batteries are practical and might be useful solutions if you only require a battery backup or storage for generated electricity. With its many advantages, such as a longer lifespan, higher efficiency, and higher energy density, installing a lithium-ion battery is frequently the best option. Despite having greater starting costs than lead-acid equivalents, lithium-ion batteries are often more useful.
Currently, most solar installations which were highly dominated by lead acid batteries due to their inexpensive budget are switching to lithium-ion batteries due to their capacity, depth of discharge, efficiency and low maintenance.
Lead-acid batteries could be a better choice in a situation where an off-grid solar system isn't routinely used. For instance, it is less expensive to retain a lead-acid battery aboard a boat or RV as a backup power supply that is only used sometimes rather than a lithium-ion battery. You will also escape many of the drawbacks of lead-acid technology, such as its shorter lifespan, thanks to the reduced utilization rate.
What is the future?
Lithium-ion batteries are shaping up to be the face of the future with continuous rapid growth due to the high demand for efficient and high-performance storage. The current developing technologies such as more portable devices and the adoption of electric vehicles EVs are proving to be a catalyst to propelling the growth of lithium-ion batteries. As the technology grows the demand is expected to also rise.
Despite the overwhelming defeat and competition from newer battery technologies, lead acid batteries are still unlikely to go out of the market any time soon. Several advantages still give lead acid batteries the hedge and make them a better choice. Some of these advantages include; a fair price of installation, recyclability, and a proven reliability and performance record. Essentially, until the newer technologies can beat that,l lead acid batteries will still be in the market.
