What is the difference between a lithium battery and a lead-acid battery? Which one is better?

by:CTECHi     2021-07-14

: Lithium batteries and lead-acid batteries are currently the two most widely used batteries. So what is the difference between these two batteries and which one is better? The following will focus on the differences between lithium batteries and lead-acid batteries.

I. Introduction to lithium batteries

Lithium batteries are a type of Batteries with aqueous electrolyte solutions. In 1912, the lithium metal battery was first proposed and studied by Gilbert N. Lewis. In the 1970s, M.S. WhitTIngham proposed and began to study lithium-ion batteries. Due to the very active chemical properties of lithium metal, the processing, storage and use of lithium metal have very high environmental requirements. Therefore, lithium batteries have not been used for a long time.

The working principle of lithium ion batteries:

Lithium ion batteries generally use lithium alloy metal oxide as the cathode material, graphite It is a negative electrode material and a battery that uses a non-aqueous electrolyte.

The reaction that occurs on the positive electrode of the charge is: LiCoO2u003du003dLi(1-x)CoO2+XLi++Xe- (electronic)

The reaction on the negative electrode of the charging is: 6C+XLi++Xe-u003dLixC6

The total reaction of the rechargeable battery: LiCoO2+6Cu003dLi(1-x )CoO2+LixC6

Anode

Anode material: There are many optional cathode materials, and most mainstream products use lithium iron phosphate salt. Comparison of different cathode materials:

Anode reaction: Lithium ions intercalation during discharge, and lithium ions deintercalation during charging. When charging: LiFePO4→Li1-xFePO4+xLi++xe-when discharging: Li1-xFePO4+xLi++xe-→LiFePO4.

Anode

Anode material: Graphite is mostly used. New research has found that titanate may be a better material.

Negative electrode reaction: Lithium ions are deintercalated during discharge, and lithium ions are intercalated during charging.

When charging: xLi++xe-+6C→LixC6

When discharging: LixC6→xLi++xe- +6C

Second, lead-acid battery introduction

Lead-acid battery (VRLA) is a kind of electrode mainly made of lead The battery is made of its oxide and the electrolyte is sulfuric acid solution. In the discharge state of a lead-acid battery, the main component of the positive electrode is lead dioxide, and the main component of the negative electrode is lead; in the charged state, the main component of the positive and negative electrodes are lead sulfate.

The nominal voltage of a single-cell lead-acid battery is 2.0V, which can be discharged to 1.5V and charged to 2.4V. In applications, 6 single-cell lead-acid batteries are often connected in series to form a nominal 12V lead-acid battery. There are also 24V, 36V, 48V and so on.

Main characteristics of lead-acid batteries

Safety seal

During normal operation, the electrolyte will not leak out of the battery terminals or casing. No free acid

The special absorbent separator keeps the acid inside. There is no free acid inside the battery, so the battery can be placed anywhere.

Venting system

When the internal pressure of the battery exceeds the normal level, the VRLA battery will release excess gas and automatically reseal to ensure There is no excess gas in the battery.

Simple maintenance

Because the gas composite system converts the generated gas into water, it is not necessary to use the VRLA battery. Need to add water.

Long service life

The use of anti-corrosion structure of lead-calcium alloy fence VRLA battery can be used for floating charge 10 -15 years.

Stable quality and high reliability

Adopt advanced production technology and strict quality control system, the quality of VRLA battery Stable and reliable performance. Voltage, capacity and sealing are 100% inspected on the line.

Safety certification

All VRLA batteries have passed UL safety certification.

3. Comparison of the difference between lithium batteries and lead-acid batteries

We know that in general, energy storage products should be compared with weight and energy. From the perspectives of density, volume energy density, service life, price, applicability, and national policies:

weight energy density

Current lithium battery energy density is generally 200~260wh/g, lead acid is generally 50~70wh/g, then the weight energy density of lithium battery is 3~5 times that of lead acid, which means that under the same capacity , Lead-acid batteries are 3 to 5 times that of lithium batteries, so lithium batteries have an absolute advantage in lightening energy storage devices.

Volume energy density

The volumetric capacity density of lithium batteries is usually about 1.5 times that of lead-acid batteries, so the same capacity Under the circumstances, the volume of lithium batteries is about 30% smaller than that of lead-acid batteries.

Life cycle

Currently the more popular material systems are ternary and iron-lithium, ternary power type lithium battery cycle The number of cycles is usually more than 1000 times, the cycle number of lithium iron phosphate batteries is more than 2000 times, and the cycle number of lead-acid batteries is usually only about 300-350 times, so the service life of lithium batteries is about 3-6 times that of lead-acid batteries.

Price

Currently, the price of lithium batteries is more expensive than lead-acid, about 3 times, but they are used in combination Life analysis, the same cost is invested, but the life cycle of lithium batteries is still longer.

Applicability

Because the safety of lithium batteries is slightly worse than that of lead-acid batteries, they need to be done well in use Various safety precautions, such as preventing external forces or accidents from damaging the lithium battery, which may cause fire or explosion; the current temperature applicability of lithium batteries is also very good, so in other aspects of adaptability, lithium batteries are not inferior For lead-acid batteries.

Use occasion

Lead-acid battery: car start, electric car battery,

Lithium batteries: mobile phones, computers, power tools, now also used in electric vehicle batteries.

Internal materials

The positive and negative electrodes of lead-acid batteries are lead oxide, metallic lead, and the electrolyte is concentrated sulfuric acid.

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Lithium battery positive and negative electrodes are lithium cobaltate/lithium iron phosphate/lithium manganate, graphite, organic electrolyte.

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