Let's explore the differences between lithium-ion batteries and lead-acid batteries. Lead acid batteries and lithium-ion batteries are both very common backup power sources. When choosing which battery is more suitable for your device application, due to the different characteristics of the two batteries, you need to consider multiple factors such as voltage, capacity, and number of cycles.
Chemical properties and structure

Lithium ion battery
The working principle of lithium-ion batteries is based on reversible electrochemical reactions between two electrodes (anode and cathode) in the electrolyte. The electrode materials used in lithium-ion batteries are usually lithium compounds (such as lithium cobalt oxide, lithium iron phosphate, etc.), and the electrolyte is a non water soluble electrolyte (organic solvent containing lithium salt). Electrodes are usually thin layers on conductive substrates, which can achieve high energy density.
Schematic diagram of lithium battery reaction

The negative electrode is usually made of graphite, and the anode in lithium-ion batteries stores lithium ions (Li ⁺) during charging, which move from the anode to the cathode during discharge. The positive electrode is usually made of graphite, and the cathode in lithium-ion batteries stores lithium ions (Li ⁺) during charging, which move from the anode to the cathode during discharge.

During the charging process, lithium ions move from the cathode through the electrolyte and embed into the anode material. During discharge, the process proceeds in reverse: lithium ions move from the anode through the electrolyte to the cathode. While lithium ions migrate through the electrolyte, electrons flow through the external circuit, generating a current that can power the device.

Lead acid battery
The working principle of lead-acid batteries involves the electrochemical reaction between lead and lead dioxide electrodes in sulfuric acid electrolyte, providing a reliable source of electrical energy. Due to the characteristics of lead based chemistry, the electrodes of lead-acid batteries are thick and bulky.
Lead acid battery reaction principle diagram Lead acid battery reaction principle diagram
energy density

The energy density of lithium-ion batteries is usually higher than that of lead-acid batteries. This means it can store more energy per unit volume or weight, making it lighter and more compact with the same energy capacity.

The volumetric energy density of lithium-ion batteries is significantly higher than that of lead-acid batteries. This means that lithium-ion batteries can store more energy per unit volume, enabling smaller and more compact battery packs.

The energy density of lead-acid batteries is lower than that of lithium-ion batteries, which results in larger volumes and heavier batteries required for the same energy storage capacity.

Similarly, the weight and energy density of lithium-ion batteries are higher than lead-acid batteries. This results in a lighter battery pack given a given energy capacity, which is crucial in applications that require consideration of weight, such as electric vehicles.
cycle life

The cycle life of a battery refers to the number of charge and discharge cycles it can undergo until its capacity drops to a specified level.

The cycle life of lithium-ion batteries is usually longer than that of lead-acid batteries. According to specific chemical composition and usage conditions, lithium-ion batteries can withstand hundreds to thousands of charge and discharge cycles.

Although lead-acid batteries are sturdy, their cycle life is usually short, especially when subjected to deep discharge.

Lithium ion batteries are suitable for applications that require long cycle life, high energy density, and lightweight, such as electric vehicles, portable electronic devices, and energy storage. Lead acid batteries remain competitive in applications where cost-effectiveness, reliability, and existing recycling infrastructure are crucial, such as car starter batteries and static power backup systems.
Discharge rate

The discharge rate of a battery refers to the speed at which it releases stored energy, usually measured in terms of C-rate.

Lithium ion batteries can achieve high discharge rates, typically ranging from 1C to 2C or higher, depending on the chemical composition and design. Even at high discharge rates, the voltage and capacity of lithium-ion batteries remain relatively stable, which is crucial for applications that require instantaneous or sustained high power output.

Lead acid batteries are usually not suitable for high discharge rate applications. The common discharge rate range for lead-acid batteries is 0.05C to 0.2C, depending on the type (such as lead-acid batteries, AGMs, or gel batteries). Some AGM (adsorption glass blanket) or high-performance lead-acid batteries can handle moderate discharge rates, up to 0.5C or slightly higher.

At high discharge rates, lead-acid batteries may experience voltage drop and capacity reduction, while the discharge rate of lithium-ion batteries remains stable, and the discharge rate of lead-acid batteries gradually decreases to 60%. This limitation makes lead-acid batteries less suitable for applications that require rapid energy release or high power demand.

Lead acid batteries are more suitable for applications that require moderate discharge rates, such as car starter batteries, backup power systems, and static applications. Due to voltage drop and reduced efficiency at high discharge rates, they are less effective in applications that require rapid discharge.

Lithium ion batteries are superior to lead-acid batteries in terms of high discharge rate. They can quickly and efficiently provide significant power output, suitable for applications that require high power impact, such as electric vehicles, power tools, and certain industrial equipment.
discharge voltage

Lithium ion batteries maintain a relatively stable voltage during most discharge cycles until the capacity approaches its end. This makes them suitable for applications that require stable voltage and consistent performance.

The nominal voltage of each battery cell in lead-acid batteries is lower than that of lithium-ion batteries. During the discharge process, their voltage will gradually decrease, especially towards the end of the capacity when the voltage drop is more pronounced. This characteristic is common in applications where battery voltage range and discharge characteristics are key factors.

In practical applications, understanding these voltage characteristics helps to select the appropriate battery type based on voltage requirements, discharge characteristic requirements, and overall performance expectations.
Charging characteristics

Lithium ion batteries can be charged quickly, and some types of lithium-ion batteries can be charged quickly without significant damage. Their self discharge rate is also lower than lead-acid batteries.

Lead acid batteries typically charge slower than lithium-ion batteries, especially when approaching full charge. Fast charging may cause heating and requires careful monitoring.

For example, a 3000 milliampere hour (mAh) lithium-ion battery, with a charging current of 1500 mAh (1.5A), theoretically takes about 2 hours to fully charge (assuming a charging rate of 1C). A 12 volt lead-acid battery with a capacity of 100 ampere hours (Ah) and a charging rate of 10 amps (approximately 0.1C) takes about 10 hours to fully charge.
Temperature influence

Lithium ion batteries perform best within the temperature range of 0 ° C to 45 ° C (32 ° F to 113 ° F). Lead acid batteries have a higher tolerance for temperature extremes than lithium-ion batteries. They can operate effectively within the range of -20 ° C to 50 ° C (-4 ° F to 122 ° F).

Lithium ion batteries are more sensitive to extreme temperatures and require careful thermal management to ensure safety and optimal performance. Cold temperatures (below 0 ° C) may temporarily reduce the capacity and power output of the battery. Extremely low temperatures may cause the battery to become sluggish, and charging or discharging at extremely low temperatures may result in irreversible damage.

Lead acid batteries have a wider operating temperature range and can better withstand high and low temperatures. Although lead-acid batteries can better withstand high temperatures, overheating can still accelerate battery aging and increase water loss.

Both types of batteries require monitoring and adherence to temperature guidelines to ensure safe operation and extend lifespan.
Application and usage

Lithium ion batteries are widely used in portable electronic devices, electric vehicles, and energy storage systems due to their high energy density, which requires maximizing energy per unit volume or weight.

Lithium ion batteries are commonly used in portable electronic devices such as laptops, smartphones, electric vehicles (EVs), and renewable energy storage systems due to their high energy density and lighter weight.

Lead acid batteries have traditionally been used for automotive starter batteries, backup power systems (UPS), and industrial applications such as forklifts and golf carts due to their durability, low cost, and suitability for high current output. Despite the low energy density of lead-acid batteries, they remain competitive in applications where cost-effectiveness, durability, and existing recycling and processing infrastructure prioritize weight and volume.
maintain

Compared to lead-acid batteries, lithium-ion batteries typically require less maintenance. They do not require checking the electrolyte or regular balanced charging. Due to their light weight, compact size, and flexible installation, lithium-ion batteries are usually easier to install. They require less structural support and have lower ventilation requirements compared to lead-acid batteries.

Lead acid batteries require regular maintenance, such as checking electrolyte levels, specific gravity, and ensuring proper charging to prevent sulfurization. Due to their heavy weight and the release of gas during charging, lead-acid batteries require a sturdy installation structure and sufficient ventilation. In addition, they also require specific maintenance access for periodic checks and services.
summary

When choosing lithium-ion batteries and lead-acid batteries, specific application requirements should be considered, including power requirements, space limitations, cost considerations, and environmental factors. Each type of battery has its unique advantages, making it suitable for different industries and applications.