Lithium ion batteries is one kind charges batteries, it basically relies on lithium ion to move between positive electrode and negative pole will work. In filling discharge process, li+ goes there and back to embed and take off between two electrode embed: When filling cell, li+ is taken off from positive electrode embed, embed through electrolyte negative pole, negative pole is in rich lithium condition; When discharge contrary. Use the material that contains lithium element to serve as the batteries of electrode commonly, it is the delegate of contemporary high-powered batteries.

 

The working principle of lithium ion batteries

 

Lithium ion batteries is negative pole with carbolic element material, make positive electrode in order to contain the compound of lithium, exist without metallic lithium, lithium is only ionic, this is lithium ion batteries. Lithium ion batteries is the floorboard that shows with lithium ion embeds compound is batteries of positive electrode material. Of lithium ion batteries fill discharge process, lithium embeds ionicly and take off namely set a process. Embed ionicly in lithium and take off in setting a process, accompany the equivalent electron such as move and lithium ion at the same time embed and take off embed (customarily anode is used embed or take off embed express, and negative pole is used insert or take off insert express) . In filling discharge process, lithium ion is in, go there and back between negative pole built-in / take off embed and insert / take off insert, be called by figure ground ” of batteries of “ rocking chair.

 

 

When undertaking charging to batteries, there is lithium ion to generate on the anode of batteries, generated lithium ion moves through electrolyte negative pole. And the carbon that serves as negative pole shows layer shape structure, it has a lot of small opening, the lithium ion that achieves negative pole embeds the small Kong Zhong of carbolic layer, built-in lithium ion is more, fill capacitance taller. Same, when should undertaking discharging to batteries (namely the process that we use cell) , embed the lithium ion emergence in layer of negative pole carbon, move again an anode. The lithium ion that answers positive electrode is more, discharge capacity is higher.

 

Set of charging current of general lithium battery comes in 0.2C between 1C, electric current is bigger, charge faster, batteries is calorific at the same time bigger also. And, too big electric current charges, the capacity is not quite full, because the electrochemistry of batteries interior reacts,need time. Follow beer same, pour too fast word to be able to produce foam, malcontent instead.

 

To batteries, use the process that discharges namely normally.

 

Lithium battery discharge needs when to notice:

 

The first, discharge electric current cannot pass big, too big electric current brings about batteries interior to give out heat, possible meeting causes permanent harm. On the mobile phone, this does not have a problem however, need not consider.

 

The 2nd, cannot pass discharge absolutely! Lithium battery most had been afraid of discharge, once spark voltage under 2.7V, bring about the likelihood batteries to discard as useless. Fortunately interior of mobile phone batteries had packed protective circuit, voltage still is done not have low the degree to attaint batteries, protective circuit can act well, stop to discharge. Can see from the graph, batteries discharge electric current is bigger, discharge size is smaller, voltage drops faster.

 

Structure of lithium ion batteries

 

 

 

Positive electrode: Active material, electric agent, dissolvent, adhesive, matrix.

 

 

When batteries discharges, from dispatches from foreign news agency the road obtains electronic electrode, right now electrode happening returns primary response. It is the electrode with high potential normally. Electrode of the cobaltic acerbity lithium in lithium ion batteries, manganese acerbity lithium.

 

Negative pole: Active material (black lead, MCMB, CMS) , adhesive, dissolvent, matrix.

 

 

When batteries discharges, outward circuit carries electronic electrode, right now electrode happening oxidation reacts. It is the electrode with low potential normally, electrode of the black lead in lithium ion batteries.

 

Diaphragmatic

 

Diaphragmatic it is to put park polar between, regard segregation as the device of electrode, jie in order to avoid polar the short circuit that the active material that go up is contacted directly and causes batteries interior. But diaphragmatic still need to be able to let electrified ion pass, in order to form access.

 

 

Diaphragmatic requirement:

 

1, ion is fully excessive big

2, mechanical sex intensity is proper

3, itself is dielectric

4, do not produce reaction with electrolyte and electrode

 

Material is qualitative: Monolayer PE (polyethylene) or three-layer is compound PP (polypropylene) + PE+PP

 

Ply: Monolayer is 0.016 ～ 0.020mm commonly, three-layer is 0.02 ～ 0.025mm commonly

 

Electrolyte

 

Crust hardware (steel casing, aluminous carapace, cover board, extremely ear, insulation piece, insulating tape)

 

Raw material of core of report of lithium ion batteries

 

Positive electrode material

 

Positive electrode material is in lithium battery market capacity is the biggest, additional the cost is higher, hold lithium battery cost about 30% , wool interest rate is low criterion 15% , tall a 70% above.

 

 

Security of battery of nickel acerbity lithium is the poorest (fill easy a kind of firecrackerfire breaking out too) , high temperature is able to bear or endure get degree of minimum (pyrolysis) , synthetic difficulty is highest.

 

Cobaltic acerbity lithium comes true the earliest commercialize application, the technology develops up to now already very mature, apply extensively already on the portable electron product of small-sized low power, wait like computer of mobile phone, notebook and digital electron product.

 

Lithium of phosphoric acid iron uses positive electrode material to have good electrochemistry performance as lithium ion batteries, fill discharge platform very smooth, the structure in filling discharge process is stable. In the meantime, this material avirulent, free from contamination, safety performance is good, can use below high temperature environment, raw material origin is extensive wait for an advantage, it is the heat that at present batteries bound develops research eagerly.

 

 

Negative pole material

 

Scale of cost of report of Zhan Li of negative pole material is inferior, basically have material of carbolic negative pole and stuff of the negative pole that be not carbon.

 

Material of carbolic negative pole: By at present batteries of commodity lithium ion is used extensively.

 

Advantage: Safe, cycling life is longer, the price is cheap, avirulent.

 

Defect: Quality is lower than energy.

 

Be not material of carbolic negative pole: Transfer for lithium by series part metallic nitride, transfer metallic oxide and material of accept rice alloy.

 

Advantage: Have very high bulk energy density.

 

Defect: Circular stability is poor, not reversible size is larger, preparation cost is higher, have not industrialization.

 

Negative pole data was not a target in order to increase capacity and circular stability, be not material with carbon element material of carbolic negative pole with all sorts of high capacities compound in order to develop carbon of high capacity, blame material of compound negative pole.

 

Diaphragmatic material

 

Commercialized diaphragmatic material basically is with polyethylene (Polyethylene, PE) , polypropylene (Polypropylene, PP) the polyolefin that give priority to (Polyolefin) kind diaphragmatic, among them PE product is main by wet craft is made, PP product basically is made by dry method craft.

 

 

The feature of PE product and PP product compares:

 

1, PP is opposite more high temperature resistant, PE is able to bear or endure relatively microtherm;

2, PP density is smaller than PE;

3, PP melting point and closed pore temperature are higher than PE;

4, PP goods is more fragile than PE;

5, PE is more sensitive to environmental stress.

 

Main diaphragmatic material product has pottery and porcelain of PE of monolayer PP, monolayer, PP+ to besmear pottery and porcelain of Fu, PE+ besmears PP/PP of PP/PE of Fu, double deck, double deck and three-layer PP/PE/PP, among them before two kinds of products basically are used at domain of 3C small cell, a few kinds of products basically are used at domain of dynamical lithium battery after.

 

Diaphragmatic material product is used in dynamical lithium battery in, diaphragmatic material of double deck PP/PP basically is produced by Chinese enterprise, use in chinese mainland, because at present level still does not have Chinese enterprise to be able to make PP and PE geminate layer,this basically is of compound film technology and ability. And what battery of lithium of global car motivation uses is diaphragmatic besmear with PP/PE of three-layer PP/PE/PP, double deck and PP+ pottery and porcelain pottery and porcelain of Fu, PE+ besmears the diaphragmatic material product such as Fu is given priority to. Meanwhile, a few otherer product of new-style and diaphragmatic material also begins implementation application in ceaseless emerge in large numbers, nevertheless, because the quantity is little price is high, still basically use in dynamical lithium battery to create a field. These products basically have: The polyester film that coating processes (PET, polyethylene Terephthalate) , cellulose film, get together acyl inferior amine film (PI) , polyamide film (PA) , ammoniac black silk ribbon or film of fragrant black silk ribbon are waited a moment. These diaphragmatic advantages are high temperature resistant, and have low temperature output, charge cycling life is long, mechanical the characteristic of intensity moderate. Taking one with another, diaphragmatic material product presents lithium battery a clear diversification development trend.

 

Electrolyte

 

Focal point of material of electrolyte of lithium ion batteries depends on high security, tall environmental suitability, main development will center in: New-style dissolvent (working temperature limits widens) , salt of ionic liquid, new-style lithium (raise environmental suitability) , additive (flame retardant, oxidation is reductive move back and forth, protection negative pole becomes film to wait) wait for a respect, with new-style, phase of negative pole data matchs, increase security, power and size, final safety applies at electric car conveniently, store can, spaceflight and more extensive field.

 

The workmanship flow of lithium ion batteries

 

 

Lithium ion batteries produces used main device

 

Vacuum planet mixer

 

 

Utility: all sorts of batteries material even mix becomes oar state.

 

Electrode spreader

 

Utility: The oar after agitate expects even film is in tinsel piece on. The besmear cloth ply that expects to the oar arrives accurately under 3 micron.

 

 

Roller press

 

 

Utility: After Tu Bu extremely piece farther squeezing ramming, increase the energy density of batteries.

 

Extremely piece cent cuts facility

 

 

Supersonic solder electric power facilities

 

 

Winding machine

 

 

Utility: Will made extremely piece winding becomes cell

 

Glove box

 

Utility: Assure to be below low humidity environment will electrolyte and roll core is enclosed together

 

 

Record fluid machine

 

Utility: The running water that assures high accuracy is changed package batteries of electrolyte vacuum infuse data inside

 

 

Turn test equipment

 

Utility: Charge the battery that has made activation, generation voltage, check the capacity of batteries at the same time.

 

The article is reprinted from sensor technology.