Top 10 Differences between Lead-Acid Batteries and Lithium-Ion Batteries

Before the invention of lithium-ion batteries in the 1970s, lead-acid batteries were predominantly used in many applications. The lithium-ion battery has begun to dominate the lead-acid battery in the market as they are even more durable. The lithium-ion battery market is expected to show a 17.23% of CAGR from 2022 to 2027. 

Both the lead-acid and lithium-ion batteries are rechargeable and can last long. In this article, let us compare and contrast the features of a lead-acid battery vs a lithium-ion battery. 

Lead-Acid vs Lithium-Ion Batteries

1. The Materials Used 

Both Lithium-ion and Lead-acid batteries work on the same principle. The primary difference lies in the material used as cathode, anode, and electrolyte. In a lead-acid battery, lead is used as the anode, and lead oxide is used as a cathode. In a lithium-ion battery, carbon is used as the anode, and lithium oxide is used as the cathode. Lead-acid batteries use sulphuric acid as an electrolyte, and li-ion batteries use lithium salt as an electrolyte. While discharging, ions flow from anode to cathode through the electrolyte, and the opposite reaction occurs while charging. 

2. Cost

Lead-acid batteries are cheaper and are easier to install when compared to Lithium-ion batteries. The price of a lithium-ion battery is two times higher than a lead-acid battery with the same capacity. However, if you compare the life of the batteries, lithium-ion lasts longer than a lead-acid battery. Hence, lead-acid batteries are cheaper only for short-term applications than lithium-ion batteries.

3. Battery Capacity

Battery capacity is the amount of energy stored in a battery per unit volume. It is a direct indicator of the active material stored inside the battery. Lithium batteries have higher battery capacity when compared to lead-acid batteries.

4. Energy Density or Specific Energy

Energy density is a significant factor in determining the type of battery needed for a specific application. It indicates the relation between battery capacity and the weight of the battery. 

Energy Density = (Nominal Battery Voltage (V) x Rated Battery Capacity (Ah)) ÷ Weight of Battery.

Lithium batteries have high specific energy when compared to lead-acid batteries. Hence, Li-ion batteries are used in EV applications.

5. Weight and Size

The energy density and battery capacity value of lithium batteries are high when compared to lead-acid batteries. Therefore, the weight and size of lithium batteries are much lower in comparison to lead-acid batteries with the same capacity. 

6. Depth of Discharge (DOD)

Depth of Discharge indicates the maximum energy of a fully charged battery that can be used without recharging. If a battery's Depth of Discharge is 50%, you can use up to 50% of the battery capacity and recharge it. If you have used it more than 50%, the battery's life cycle will get affected. The depth of discharge is 50% for lead-acid batteries, and 80% for lithium batteries, respectively. This means you can use the lithium-ion battery for a longer period without recharging. The modern li-ion battery that is manufactured today is even more efficient, with a DOD of 100%.

7. Durability

The durability of the battery is determined by the time duration it can last. Lead-acid batteries can last up to 2 years if well maintained, i.e. recharging it after 50% of the battery is utilized. If it is fully drained or above 80%, it can sustain only for 350 cycles or one year. Instead, a lithium-ion battery has a warranty period of 10 years and can sustain for 10,000 cycles.

8. Cycle Life

Cycle life is the number of charging and discharging cycles a battery can undergo without compromising its performance. Usually, lithium-ion batteries possess a cycle life of 5000, and complete discharge does not affect the life cycle. Whereas a lead-acid battery lasts for 300 to 500 cycles.  The complete discharge of the battery significantly affects its life cycle.

9. Charging Time

Lithium-ion batteries charge much faster than lead-acid batteries. If a lead-acid battery takes eight hours to charge, a lithium-ion battery would probably take less than two hours to charge, provided they both have the same capacity. Li-ion batteries are eight times faster than lead-acid batteries while charging. This is one of the reasons why Lithium-ion batteries are deployed in most EVs

10. Safety

There are many reasons for failures that can occur in batteries. It is your responsibility to be cautious while using batteries of high voltage. In both lead-acid and lithium-ion batteries, overcharging may lead to an explosion. 

The sulfuric acid in the lead-acid battery is highly corrosive, and there is a chance of leakage. If overcharged, hydrogen and oxygen gases may evolve, leading to an explosion. In lithium-ion batteries, there are high chances for thermal runaway. Thermal runaway is the condition that occurs when the heat generated within the battery exceeds the heat dissipated to the surroundings. The thermal runaway also has the potential to trigger a battery explosion. It is the responsibility of the BMS engineer to build robust battery pack systems to reduce the risk of failures. CATL, Panasonic Corporation, Clarios and Bharat Power Solutions are some of the key players in manufacturing batteries. Based on the usage their market is classified into automotive, aerospace, energy storage, solar, military, defence and others. Each sector has a set of guidelines to be followed for the manufacturing of batteries to ensure safety.

To compare the advantages of lead-acid vs a lithium-ion battery, you must first decide on the application. For EV applications and areas that require a long-lasting power supply, a lithium-ion battery would be the ideal option. For power backup applications like UPS for computers and inverters, a lead-acid battery may be the cost-effective option. A BMS engineer with knowledge in battery technology has to perform a lead acid vs lithium-ion battery comparison for each application to choose the right option. 

The dependency on batteries is increasing, and the market for batteries is expected to surge up to USD 90 billion by 2025. A course in battery technology will equip you with the necessary skillsets to build a robust battery pack design for EV applications. Skill-Lync can offer you hands-on training in MATLAB and Simulink to kickstart your career as a BMS engineer.