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Comparison of the Lead Acid Battery and Li-ion Batteries

8th June, 2021

Energy Density

Energy density (Wh/L) of a battery indicates the amount of energy it can store in a given space, battery chemistry with higher energy density can store large energy/capacity in a less space, proving to be more convenient and more useful for applications.

Li-ion batteries have more than double the energy density of the Lead Acid Batteries. Means they can store the same amount of energy the lead acid in half the size. Lead acid Batteries have energy Density in the range of 80 – 100 Wh/L while the Li-ion batteries have energy density above 250Wh/L.

Efficiency

Charge-discharge efficiency of a battery refers to the amount of energy that can be extracted from the battery from the stored energy.

Leads Acid batteries have 80-85% charge discharge efficiency, meaning if we charge the battery with 1000W we can get 800-850W of that energy from the battery.

Li-ion batteries offer over 95% of efficiency, meaning for every 1000W energy stored we can get over 950W of energy output in standard conditions.

Depth of Discharge (DOD)

DOD of a battery is very important factor which determines the life cycle and performance of the battery. DOD refers to the percentage of energy which has been discharged from battery with respect to the overall capacity. Manufacturers specify a specific DOD percentage for the batteries so that the performance of the battery is not negatively impacted.

Lead acid batteries generally have 50% DOD recommended, if it is discharge below 50% the battery life and performance is effected in long run.

Li-ion batteries have a high DOD of about 80%, means Li-ion battery offers high effective capacity than the lead acid counterpart.

Charge Discharge Rate

Li-ion battery have a greater advantage over the lead acid battery as they can be efficiently charged and discharged at the higher current rates. It means if we have a Li-ion battery and a lead acid battery of same capacity (Ah) than the Li-ion battery can be charged in less time than the lead acid battery. Normally recommended Charge rate for Lead acid batteries is 0.3C while different Li-ion chemistries can be charged up even at very high C rate (2C, 5C and high).

In case of discharge the li-ion battery can be discharged at higher C rates (2C, 3C and even high) with some loss in capacity while the capacity loss is very high in case of Lead Acid battery. If the lead acid battery is discharged over 0.5C it suffers huge capacity loss.

Life Span

Every battery chemistry degrades with the usage. Life cycle of a battery is defined as the period during which the charge storing capacity of the battery reduces to 80% of its initial capacity. Life cycle of a battery depends on various factors as the DOD, Charge-Discharge rate, Environmental Conditions as Temperature and many other factors.

In general Lead acid batteries have a life cycle of about 1000 cycles while the Li-ion batteries have a life span of 2000-2500 cycles. Some Li-ion chemistries offers above 10000 cycle of operation.

Self-discharge and shelf life

Li-ion batteries have very small self-discharge rate than the lead acid batteries, for this they can retain charge for much more time than the lead acid battery. This also offer the Li-ion battery high shelf life means they can be kept for long time without usage while the lead acid batteries have to be charged at small intervals.

Maintenance

Li-ion batteries have Zero Maintenance while the traditional lead acid battery needs maintenance from time to time. For prolong life of lead acid battery they have to be regularly monitored for voltage, overcharge limit, water level maintenance, and electrolyte replacement. Though the new type of lead acid batteries as AGM and VRLA do not need much maintenance but they are expensive than the traditional lead acid batteries.

Environmental effects

For the same energy storage capacity, Lead Acid battery require many times more raw material than the li-ion batteries. Lead is highly hazardous to humans and lead processing industry is also very energy intensive. Lead, mercury and cadmium are highly toxic metals that are used in battery manufacturing for decades, their inefficient and improper disposal has caused considerable environmental damage over the years. Li-ion also uses rare earth metals and their mining is also very energy intensive process but the carbon footprint of the li-ion batteries is much lesser than the lead acid batteries.

Recycling

Lead acid batteries being a very mature technology have an established recycling industry while the Li-ion recycling is in very nascent stage with very high future potential.

Expertise & Production Capabilities In India

Lead acid battery have been used for commercial/industrial and domestic applications for over a decade. Lead Acid Batteries have a very well established large scale manufacturing base.

For Lithium ion batteries though have been used in electronic applications as Laptops, mobile phones and other electronic gadgets for 10 to 20 years, they are still lacking in large scale manufacturing and we are still dependent on other countries. With the help of government policies and industrial interests the manufacturing base is bound to expand in coming years.

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