Lithium metal battery and lithium ion battery difference
The main difference between lithium metal batteries and lithium ion batteries is that lithium metal batteries are disposable batteries with greater capacity. And lithium-ion batteries are secondary batteries, which can be recharged repeatedly; like dry cell batteries, lithium metal batteries use lithium metal as the electrode to generate electricity through the oxidation of lithium metal, which can only be used once. Unable to be recharged, lithium-ion batteries are a secondary high-performance battery using lithium cobaltate or other materials as the positive electrode and carbon as the negative electrode, filled with electrolyte in the middle.
Lithium-ion battery
Lithium-ion battery: It is a secondary battery (rechargeable battery), which works mainly by moving lithium ions between the positive and negative electrodes. During charging and discharging, Li+ is embedded and de-embedded back and forth between the two electrodes: when charging, Li+ is de-embedded from the positive electrode and embedded in the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state; the opposite is true when discharging.
(1) positive electrode - the active material is generally lithium manganate or lithium cobaltate, lithium nickel cobalt manganate materials, electric bicycles are commonly used lithium nickel cobalt manganate (commonly known as ternary) or ternary + a small amount of lithium manganate, pure lithium manganate and lithium iron phosphate is gradually fading out due to the large size, poor performance or high cost. The conductive electrode fluid uses electrolytic aluminum foil with a thickness of 10 - 20 microns.
(2) diaphragm - a specially formed polymer film, the film has a microporous structure, allowing lithium ions to pass freely, while electrons can not pass.
(3) Negative electrode - the active material is graphite, or carbon with a structure similar to graphite, and the conductive collector uses electrolytic copper foil with a thickness of 7-15 microns.
(4) organic electrolyte - dissolved lithium hexafluorophosphate carbonate solvent, polymer use gel electrolyte.
(5) battery shell - divided into steel case (square type is rarely used), aluminum case, nickel-plated iron case (cylindrical battery use), aluminum plastic film (soft packaging), etc., and the battery's cap, but also the positive and negative lead ends of the battery.
Lithium-ion battery working principle
Lithium-ion battery uses carbon material as the negative electrode and lithium-containing compound as the positive electrode, no lithium metal exists, only lithium ions. Lithium-ion battery is a general term for a battery with lithium ions embedded in a compound as the positive electrode material. The charging and discharging process of lithium ion battery is the embedding and de-embedding process of lithium ion. In the lithium ion embedding and de-embedding process, accompanied by the lithium ion equivalent electron embedding and de-embedding (customary positive electrode with embedded or de-embedded, and negative electrode with insertion or de-insertion said). During the charging and discharging process, lithium ions are embedded/de-embedded and inserted/de-inserted back and forth between the positive and negative electrodes, which is imaginatively called a "rocking chair battery".
When the battery is charged, lithium ions are generated at the positive electrode of the battery, and the generated lithium ions move through the electrolyte to the negative electrode. The carbon as the negative electrode is in the form of a layer structure, which has many micro-pores, and the lithium ions reaching the negative electrode are embedded in the micro-pores of the carbon layer, and the more lithium ions embedded, the higher the charging capacity. Similarly, when the battery is discharged (i.e., 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 that return to the positive electrode, the higher the discharge capacity.
General lithium battery charging current is set between 0.2C and 1C, the higher the current, the faster the charge, while the battery heat is also greater. Moreover, too much current charging, the capacity is not full enough, because the electrochemical reaction inside the battery takes time. Just like pouring beer, if you pour too fast, it will produce foam, but not full.
Advantages of lithium-ion batteries
1) High voltage
The working voltage of the single cell battery is as high as 3.7-3.8V (3.2V for lithium iron phosphate), which is three times higher than that of Ni-Cd and Ni-MH batteries.
2）High specific energy
The actual specific energy that can be achieved is about 555Wh/kg, that is, the material can reach a specific capacity of 150mAh/g or more (3-4 times that of Ni-Cd, 2-3 times that of Ni-MH), which is close to about 88% of its theoretical value.
3）Long cycle life
Generally can reach more than 500 times, or even more than 1000 times, lithium iron phosphate can reach more than 2000 times. For small current discharge appliances, the battery life, will multiply the competitiveness of the appliance.
4）Good safety performance
No pollution, no memory effect. As Li-ion predecessor of lithium batteries, because of the formation of lithium metal dendrites prone to short circuit, reducing its application areas: Li-ion does not contain cadmium, lead, mercury and other elements of environmental pollution: part of the process (such as sintered) of Ni-Cd batteries have a major drawback of the "memory effect", which seriously constrains the use of batteries, but Li-ion does not exist. But Li-ion does not have this problem at all.
5）Small self-discharge
The self-discharge rate of a fully charged Li-ion battery at room temperature is about 2% after 1 month of storage, which is much lower than 25-30% for Ni-Cd and 30-35% for Ni-MH.
6) Fast charging
1C charging 30 minutes capacity can reach more than 80% of the nominal capacity, phosphor-iron batteries can reach 10 minutes charging to 90% of the nominal capacity.
7）Working temperature
Operating temperature is -25~45°C, with the improvement of electrolyte and cathode, expect to expand to -40~70°C.
What is the difference between lithium metal batteries and lithium ion batteries?
Disadvantages of lithium-ion battery
Aging
Unlike other rechargeable batteries, the capacity of Li-ion batteries declines slowly, related to the number of uses, and also related to temperature. This decline can be expressed as a decrease in capacity or as an increase in internal resistance.
Recycling rate
Approximately 1% of new factory products need to be recycled for various reasons.
Intolerance to overcharging
When overcharged, excess embedded lithium ions are permanently fixed in the lattice and cannot be re-released, which can lead to short battery life.
Intolerant to over-discharge
When overdischarged, the electrode is de-embedded with too many lithium ions, which can lead to collapse of the lattice, thus shortening the life of the battery.
Lithium metal battery
Lithium battery is a kind of energy storage battery using lithium metal as electrode, with very high specific energy, early divided into disposable batteries and rechargeable lithium batteries, but after the accident of rechargeable lithium batteries, the civilian market has rarely seen rechargeable lithium batteries. Lithium-ion rechargeable batteries actually use the concentration difference of lithium ions for energy storage and discharge, there is no lithium metal in the battery.
Lithium metal batteries are the same as the principle of ordinary dry cell batteries, it is used as the electrode, through the corrosion of lithium metal or called oxidation to generate electricity, used up and waste, can not be recharged.
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