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What Is The Difference Between A Lithium Metal Battery And A Lithium Ion Battery?
- Sep 05, 2018 -

Abstract: Metal lithium batteries and lithium-ion batteries are all lithium batteries, so what is the difference between lithium metal batteries and lithium-ion batteries? The following will tell you in detail the difference between the two.

Lithium-ion battery introduction

Lithium-ion battery: It is a secondary battery (rechargeable battery) that relies on lithium ions to move between the positive and negative electrodes to work. During charging and discharging, Li+ intercalates and deintercalates between the two electrodes: when charging, Li+ is deintercalated from the positive electrode, and the electrolyte is embedded in the negative electrode, and the negative electrode is in a lithium-rich state;

(1) Positive electrode - the active material is generally lithium manganate or lithium cobalt oxide, lithium nickel cobalt manganese oxide material, electric bicycle is generally used nickel cobalt cobalt manganate (commonly known as ternary) or ternary + small amount of lithium manganate, pure Lithium manganate and lithium iron phosphate are gradually faded out due to their large size, poor performance or high cost. The electrode fluid is an electrolytic aluminum foil having a thickness of 10 to 20 μm.

(2) Separator - a specially formed polymer film with a microporous structure that allows lithium ions to pass freely without electrons passing.

(3) Negative electrode - The active material is graphite, or carbon of approximately graphite structure, and the conductive current collector uses an electrolytic copper foil having a thickness of 7-15 μm.

(4) Organic electrolyte - a carbonate solvent in which lithium hexafluorophosphate is dissolved, and a polymer electrolyte is used as the polymer.

battery case - divided into steel shell (square type is rarely used), aluminum shell, nickel-plated iron shell (used in cylindrical battery), aluminum plastic film (soft packaging), etc., as well as the battery cap, but also the battery is positive Negative terminal.

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How lithium-ion batteries work

Lithium-ion batteries use a carbon material as the negative electrode and a lithium-containing compound as the positive electrode. No lithium metal exists, only lithium ions. This is a lithium ion battery. A lithium ion battery is a general term for a battery in which a lithium ion intercalation compound is used as a positive electrode material. The charging and discharging process of a lithium ion battery is a process of intercalating and deintercalating lithium ions. In the process of intercalation and deintercalation of lithium ions, it is accompanied by embedding and deintercalation of equivalent electrons with lithium ions (customly, the positive electrode is represented by embedding or deintercalation, and the negative electrode is represented by insertion or deintercalation). During charge and discharge, lithium ions are intercalated/deintercalated and inserted/deintercalated between the positive and negative electrodes, and are aptly referred to as "rocking chair batteries".

When the battery is charged, lithium ions are generated on the positive electrode of the battery, and the generated lithium ions move to the negative electrode through the electrolyte. The carbon as the negative electrode has a layered structure, and it has many micropores. The lithium ions reaching the negative electrode are embedded in the micropores of the carbon layer, and the more lithium ions are embedded, the higher the charging capacity. Similarly, when the battery is discharged (ie, the process we use the battery), the lithium ions embedded in the carbon layer of the negative electrode come out and move back to the positive electrode. The more lithium ions return to the positive electrode, the higher the discharge capacity.

Generally, the charging current of the lithium battery is set between 0.2C and 1C. The larger the current, the faster the charging and the greater the heat of the battery. Moreover, excessive current charging, the capacity is not full, because the electrochemical reaction inside the battery takes time. Just like pouring beer, if it is too fast, it will produce bubbles, but it will not be full.

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Lithium-ion battery advantages

1) High voltage

The operating voltage of the single cell is as high as 3.7-3.8V (3.2V for lithium iron phosphate), which is three times that of Ni-Cd and Ni-MH batteries.

2) Larger than energy

The actual specific energy that can be achieved is about 555Wh/kg, that is, the material can reach a specific capacity of 150 mAh/g or more (3--4 times Ni-Cd, 2--3 times Ni-MH), which is close to its theory. A value of about 88%.

3) Long cycle life

Generally, it can reach more than 500 times, or even more than 1000 times, and lithium iron phosphate can reach more than 2000 times. For small current discharge appliances, the life of the battery will double the competitiveness of the appliance.

4) Good safety performance

No pollution, no memory effect. As a Li-ion predecessor lithium battery, metal lithium is liable to form dendrites, which reduces its application: Li-ion contains no environmentally harmful elements such as cadmium, lead, and mercury: some processes (such as sintering) One of the major drawbacks of Ni-Cd batteries is the "memory effect", which severely constrains the use of batteries, but Li-ion does not have this problem at all.

5) Small self-discharge

The self-discharge rate of fully charged Li-ion storage at room temperature for 1 month is about 2%, which is much lower than 25-30% of Ni-Cd and 30-35% of Ni-MH.

6) Fast charging

The 1C charging capacity can reach more than 80% of the nominal capacity in 30 minutes, and the ferrophosphorus battery can be charged to 90% of the nominal capacity in 10 minutes.

7) Working temperature

The operating temperature is -25 to 45 ° C. With the improvement of the electrolyte and the positive electrode, it is expected to be widened to -40 to 70 ° C.

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Lithium-ion battery disadvantages

Aging

Unlike other rechargeable batteries, the capacity of a lithium-ion battery will slowly decline, depending on the number of uses and temperature. This phenomenon of decay can be expressed as a decrease in capacity or as an increase in internal resistance.

Recovery rate

About 1% of new products need to be recycled for various reasons.

Intolerant overcharge

When overcharged, the excessively embedded lithium ions are permanently fixed in the crystal lattice and cannot be released any more, resulting in a short battery life.

Intolerance

During overdischarge, the electrode deintercalates too much lithium ions, which can cause the lattice to collapse and shorten the life.

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Metal lithium battery

Lithium battery is a kind of energy storage battery using metal lithium as the electrode. Its specific energy is very high. It was divided into disposable battery and rechargeable lithium battery in the early stage. However, after the accident of rechargeable lithium battery, it is rarely seen in the civilian market. Rechargeable lithium battery. Lithium-ion rechargeable batteries actually use the difference in concentration of lithium ions for energy storage and discharge, and there is no metal lithium in the battery.

The metal lithium battery has the same principle as the ordinary dry battery. It uses metal lithium as an electrode to generate electric energy through corrosion or oxidation of metal lithium. When it is used up, it is discarded and cannot be charged.

The difference between metal lithium battery and lithium ion battery

The main difference is that the lithium metal battery is a disposable battery, and the lithium ion battery is a rechargeable battery! The principle of metal lithium battery is the same as that of ordinary dry battery. It uses metal lithium as the electrode to generate electric energy through corrosion or oxidation of metal lithium. When it is used up, it is discarded and cannot be charged; lithium ion battery generally uses lithium cobalt oxide as positive electrode. The carbon is used as a negative electrode, and the electrolyte is filled in the middle to form an ion free passage, and the separator is used to separate the positive and negative electrodes to prevent short circuit. When charging, lithium ions migrate from the lithium cobaltate due to the electric field, and pass through the pores in the separator in the electro-hydraulic solution, and reach the negative electrode and react with carbon to form lithium carbide; in contrast, the lithium ion returns to the positive electrode. It is the charging and discharging process of a lithium ion battery.


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