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1、锂离子电池基本原理、配方及工艺流程（Basic principle, formulation and process flow of lithium ion battery）This article is contributed by a9htPdf documents may experience poor browsing on the WAP side. It is recommended that you first select TXT, or download the source file to the local view.Principle and process flow
2、of lithium ion batteryA principle of 1 LiCoO2 + + structure cathode conductive agent binder (PVDF) + collector (aluminum foil) 2 + + cathode structure of graphite conductive agent, thickening agent (CMC) + binder (SBR) + collector (copper) anode cathode3 the working principle of the 3.1 charging pro
3、cess: a power to charge the battery, the anode of Electronic E from an external circuit to the cathode, lithium ion is Li+ from the cathode electrolyte, jump over the diaphragm crooked hole, swim to negative electrode and early electronic ran. Together.The positive reaction of LiCoO2? Li1-xCoO2 + xL
4、i+ + Xe (Electronic) negative reaction of 6C + xLi+ + Xe? LixC6 3.2 battery discharge constant current discharge and constant resistance discharge, constant current discharge is in fact the external circuit with a variable resistor can change with the change of the voltage that is the essence of con
5、stant resistance discharge in batteries with a resistor to make electronic through. Thus, as long as the negative electron can not run from the negative to the positive electrode, the battery will not discharge. Electronic and Li+ are at the same time of action, the same direction but different road
6、s, discharge, electron from the cathode to anode through electron conductor, lithium ion Li+ jumped from the cathode electrolyte, passing through the diaphragm crooked hole, swim to the cathode, and early electronic ran with the together. 3.3 charge discharge characteristics of batteries cathode usi
7、ng LiCoO2, LiNiO2, LiMn2O2, LiCoO2 which is a layer of crystal structure is very stable, but when taken x Li ions from LiCoO2, its structure may change, but whether the change depends on the size of X. It is found that when x 0.5, the structure of Li1-xCoO2 is extremely unstable, and crystal collaps
8、e occurs, and its external appearance is the final termination of the core. Therefore, the use of electric core in the process should be limited by charging voltage to control the Li1-XCoO2 value of X, the general charge voltage is not greater than 4.2V, then x is less than 0.5, then the crystal sha
9、pe of Li1-XCoO2 is still stable. The negative C6 itself has its own characteristics, when the first time after formation, the positive LiCoO2 Li was negative charge to C6, when Li returned to LiCoO2 in the cathode discharge, but there must be a part of the Li formation after in the negative C6 cente
10、r, in order to ensure the normal discharge of Li embedded next time, otherwise the electric core overwhelming very short, in order to ensure that there is a part of Li in C6 negative, generally by limiting the discharge lower limit voltage to achieve: charging cap voltage less than 4.2V, the lower d
11、ischarge voltage greater than 2.5V. The principle of memory effect is crystallization, which hardly occurs in lithium batteries. However, the capacity of lithium ion batteries will still decline after repeated charging and unloading, because the reasons are complex and varied. The main change is pos
12、itive and negative pole material itself, from the molecular level, hole structure on negative pole for lithium ions will gradually collapse, blocking; from the chemical viewpoint, is the active anode material passivation, other compounds by the reaction of side. Physically, the cathode material is g
13、radually peeled off. In a word, the number of lithium ions in the battery that can move freely during charging and discharging is reduced. Overcharge and over discharge of lithium ion battery positive and negative pole cause permanent damage, from the molecular level, can be understood intuitively,
14、excessive discharge will lead to excessive release of carbon anode of lithium ion and the lamellar structure collapse, will put too much lithium ion into the carbon anode structure to go over charging, and makes some of the lithium ion never released. The unsuitable temperature will cause other reac
15、tions inside the lithium ion battery to produce compounds that we do not want to see,Therefore, a protective temperature control diaphragm or electrolyte additive is arranged between a plurality of lithium ion battery positive and negative electrodes. When the battery is heated to a certain extent,
16、the composite film hole is closed or the electrolyte is denatured, and the internal resistance of the battery is increased until the circuit is broken. The battery is no longer heating up, and the battery charging temperature is normal. Two formula and process of lithium battery 1. positive and nega
17、tive formula1.1 positive formula: LiCoO2 + + + liquid adhesive conductive agent (aluminum foil) LiCoO2 (10 m): 96% (Carbon ECP) 2% conductive agent, binder (PVDF 761) 2% NMP (increased adhesion): solid material weight ratio 810:1496 6000cps (a) positive viscosity control temperature of 25 rotor 3);
18、b) NMP weight shall be appropriately adjusted to viscosity is appropriate; c) special attention to the influence of temperature and humidity on the viscosity of the cathode active material:?: lithium cobalt oxide cathode active material, lithium ion source, lithium source to improve battery. Nonpola
19、r substances, irregular shape, particle size of D50 is 6-8 m, the water content is less than 0.2%, usually alkaline, pH value is about 10-11. Lithium manganate? Nonpolar substances, irregular shape, particle size of D50 is 5-7 m, the water content is less than 0.2%, usually is alkaline, pH value is
20、about 8. Conductive agent: chain material, water content 1%, particle size is generally 1-5 mu m. Usually the use of superconducting carbon black with excellent conductivity, such as Carbon ECP and ECP600JD Ketjen black, its role:? Improve the electrical conductivity of the cathode, the electronic c
21、onductivity of the cathode active material compensation? To improve the uptake of cathode electrolyte, increasing the reaction interface, reduce polarization. PVDF adhesives: nonpolar materials, chains, molecular weight ranging from 300000 to 3000000; after water absorption, molecular weight decreas
22、ed, viscosity becomes worse. It is used to bond cobalt lithium and conductive agent to aluminium foil or aluminium net. Commonly used brands such as Kynar 761. NMP: a weak polar liquid used to dissolve / swell PVDF and to dilute slurries. Collecting fluid (positive lead): made of aluminium foil or a
23、luminium belt.?1.2 negative formula: graphite conductive agent + + thickener binder (CMC) + (SBR) + collector (copper) anode materials (graphite): 94.5% conductive agent (Carbon ECP): 1% (Ketjen black superconducting) binder (SBR): 2.25% (SBR = styrene butadiene rubber latex Thickener (CMC) (CMC = 2
24、.25%): sodium carboxymethyl cellulose) water: solid material the weight ratio of 1600:1417.5 to a) b) C (5000-6000cps) negative viscosity control temperature of 25 rotor 3) need to adjust the weight of water, to achieve sticktness requirement is appropriate; paying special attention to the effect of
25、 temperature and humidity on viscosity2. positive and negative mixing material graphite: negative electrode active material constitutes the main material of negative reaction, mainly divided into two categories: natural graphite and synthetic graphite. Nonpolar substances are easily contaminated by
26、non-polar materials, easy to disperse in non-polar materials, not easy to absorb water, and are difficult to disperse in water. The contaminated graphite is easily re agglomerated after being dispersed in water. The average particle size D50 is about 20 m. The particles are various in shape and irre
27、gular in shape, mainly spherical, flaky, fibrous, etc. Conductive agent: its role as:?Improve the conductivity of negative electrode and compensate the electronic conductivity of negative active material. Improve reaction depth and utilization ratio. Prevent dendrite formation. Using the liquid abso
28、rbency of conductive material, the reaction interface is improved and the polarization is reduced. (optional or added according to the size distribution of graphite). Additives: reduce irreversible reactions, increase adhesion, improve slurry viscosity, prevent slurry precipitation, thickening agent
29、 / precipitation inhibitor (CMC): high polymer compounds, soluble in water and polar solvents. ? isopropanol: weak polar polar substances, after adding the binder solution can be reduced, improving the compatibility of graphite and binder solution; strong defoaming effect; easy to adhesive mesh cata
30、lytic chain, improve the bond strength.5 steps a) will NMP into the hybrid machine (100L) to 80? C, take PVDF to join them, starting up; parameter settings: speed was 25 rpm, stirring 115-125 minutes; 2 b) connected to the cooling system, dry grinding, anode will have an average of four times, each
31、time interval of 28-32 third minutes, feeding materials need to add NMP, fourth NMP after feeding; set power mixer parameters: speed of 20 + / 2 c) fourth times feeding 30 + minutes after high speed stirring, time for 480 + minutes; set 210 hybrid machine parameters: 30 + / revolution rotation, 25 +
32、 rpm; 22 D): vacuum mixing power mixer with vacuum, keep the vacuum is -0.09Mpa, stirring for 30 + minutes; set 2 hybrid machine parameters: the revolution of 10 + 8 + minutes, rotation E / 22) 250-300 ml of slurry, using the viscosity measuring viscosity; testing conditions: rotor No. 5, speed 12 o
33、r 30rpm, the temperature range of 25? C; F) the cathode material was removed from the colloid mill, sieving hybrid machine, while the stainless steel bowl affixed logo, and pull pulp equipment operator after the transfer into the slurry process. 2.1.6 note a), cleaning equipment and working environm
34、ent; b) when operating the machine, to avoid Caution!, hit the head. 2.2 pretreatment of 2.2.1 raw materials for negative mixing: 1) graphite: A and mixing, so that the raw materials are homogenized and the consistency is improved. B, 300400, C bake at normal pressure to remove surface oil2)To impro
35、ve the compatibility with water-based adhesives, to repair the edges and corners of round graphite (some materials are to maintain surface characteristics, do not allow baking, or reduce the effectiveness). Water binder: appropriate dilution, improve dispersion ability.2.2.2 blending, wetting and di
36、spersing: 1) graphite and adhesive solutions differ in polarity and are difficult to disperse. 2) the initial wetting of the graphite with an aqueous solution of alcohol will then be combined with the binder solution. 3) should be appropriate to reduce the concentration of agitation, improve dispers
37、ion. 4) the dispersion process reduces the distance between polar substance and non-polar substance, and increases potential energy or surface energy. Therefore, for endothermic reaction, the overall temperature decreases when stirred. If conditions permit, proper mixing temperature should be increa
38、sed so as to make heat absorption easier, while improving flowability and reducing dispersion difficulty. 5) mixing process, such as adding vacuum degassing process, excluding gas, and promote solid-liquid adsorption, the effect is better. 6) dispersion principle, dispersion method and the related c
39、ontent of the positive ingredients, 2.2.3 dilution: the slurry is adjusted to a suitable concentration, easy to coating. 2.2.4 material milling 1) and Ketjenblack ECP negative will be poured into the barrel with ball milling (grinding ball material: =1:1.2) was milled in roller bottles and on the sp
40、eed control in the 60rmp above; 2) the end of 4 hours, sieving separating ball milling; 2.2.5 operation step 1) pure water is heated to 80 to C into power? Mixer (2L) 2) CMC, stirring 60 + minutes; set 2 hybrid machine parameters: the revolution of 25 + minutes rotation was 15 + / 223); adding SBR a
41、nd deionized water, stirring for 60 + minutes; set 2 hybrid machine parameters: the revolution of 30 + minutes, rotation 20 + R / min; 224) negative dry four times average order to join, feeding while adding pure water, a time interval of 28-32 minutes; hybrid machine setting parameters: the revolut
42、ion of 20 + RPM rotation was 15 + 225 rpm; Fourth) feeding 30 + minutes after high speed stirring, time for 480 + minutes; set 210 hybrid machine parameters: the revolution of 30 + RPM rotation was 25 + / 226); vacuum mixing: hybrid machine connected to the vacuum, maintain the vacuum degree of -0.0
43、9 to 0.10Mpa, mixing 30 set 2 + minutes; hybrid machine parameters: the revolution of 10 + minutes rotation was 8 + / 227) and 500 ml of slurry, using viscometer viscosity measurement;Test conditions: rotor No. 5, speed 30rpm, temperature range of 25? C; 8) the anode material was removed from the hy
44、brid abrasive, sieving machine, at the same time, stainless steel basin pasted logo, and the slurry equipment operator after the transfer into the slurry process. 2.2.6 note 1), cleaning equipment and working environment; 2) when operating the machine, to avoid Caution!, hit the head.Ingredients not
45、e:What?To prevent the mixing of other impurities; prevent slurry spatter; slurry concentration (solid content) from high to low is gradually adjusted, to avoid increasing the trouble; in a stirred batch process should pay attention to shaving and scraping the bottom, to ensure uniform dispersion; sl
46、urry for long time use, in order to avoid precipitation or lower uniformity; the baking material must be sealed after cooling can be added, in order to avoid the material properties of components change; stirring time the length of the equipment performance, material quantity; use the slurry agitato
47、r with difficulty can be replaced, can not replace the adjustment speed from slow to fast, so as not to damage the equipment;? Before discharge to pulp sieving to remove large particles caused by the broken belt to prevent coating;? The batching personnel to strengthen the training, to ensure that t
48、heir master professional knowledge, in order to avoid the disaster; the key ingredient in? In the scattered evenly, master the center, other ways can be adjusted. 3. battery 3.1 pole piece size 3.2 slurry technology a) collector size (cathode aluminum foil), batch coating anode (copper), b) batch co
49、ating slurry weight requirements of electrode of the first surface double weight (g) surface density (mg/cm2) weight (g) surface density (mg/cm2). 3.3 pieces of a) cathode slurry after the following steps: cutting large pieces cut sheet (with baking sheet) said rolling pole welding b) anode slurry after the following steps: cutting large cut small piece weighing (with baking sheet) sheet electrode welding 3.4 rolling electrode electrode with 3.5 requirements the film side case nu