Fast charging type lithium ion batteryTechnical field
The present invention relates to a kind of fast charging type lithium ion batteries.
Background technique
In all energy forms, electric energy is to be easiest to using, most clean and environmental protection and the highest energy of efficiency, battery be mostThe device of good storage electric energy, in all battery products, lithium battery is that most young, most advanced, technology contains gold in the world at presentHighest, the maximum energy products of energy density are measured, lithium battery has the operation is stable range wide, discharging voltage balance, self-discharge rateIt is low, the advantages that long service life, it has been widely used in various fields, especially space flight and aviation, military affairs, long-life instrument instrumentTable, cycles the fields such as automotive electronics, mobile digital product at material flow tracking.
18650 type of high-rate type lithium ion cell of domestic production at present can continue the peak capacity of 20A current dischargeFor 2000mAh, rate of charge is generally in 1C, and battery filling time is about at 70 minutes or more.But with cordless power toolThe frequency of use of professional development, electric tool is higher and higher, more and more, the use for the scene demand that double cell packet interleaving usesWhile using electric tool, another reserve battery packet is charging simultaneously at family, convenient for being used alternatingly for battery pack, but it is electricChi Bao's uses the time normally between 30-40 minutes, and therefore, the battery pack charging time of specialized demand should control at 30 pointsWithin clock.
When due to quick charge, rate travel of the lithium ion between battery plus-negative plate is accelerated, de- from anode in lithium ionIt when embedding, need quickly to be moved to cathode and insertion is received by negative electrode material, to guarantee that normal charging reaction carries out.HereinIn reaction process, if the charging current electron transfer rate of battery core application is not achieved in the lithium ion insertion rate of negative electrode material,Lithium metal will be caused in the precipitation of negative terminal surface, the precipitation of lithium metal is irreversible reaction, and the lithium metal of precipitation can not putAnode is migrated back when electricity reaction, so that causing the reversible capacity of battery core reduces.Lower battery core active material packed density and compared withBig electrode area can increase the migration and insertion speed of lithium ion, so that the rapid charging performance of battery core is improved, but it is lowerBattery core active material packed density and biggish electrode area can reduce the energy density of battery core simultaneously, and need more auxiliaryCollector is helped, to be pressed further by the filling space of active material, reduces the energy density of battery core.Therefore, it is necessary to balanceContradiction that is, in the rapid charging performance for improving battery core, while guaranteeing required battery core energy density index.
Summary of the invention
Goal of the invention: the object of the present invention is to provide a kind of fast charging type lithium ion batteries, and there is high battery core energy density to refer toMark also has the rapid charging performance for stablizing battery core simultaneously.
Technical solution: fast charging type lithium ion battery of the present invention, including nickle cobalt lithium manganate anode and graphite cathode；It is rightNickle cobalt lithium manganate anode partial size optimal screening is mixed into the anode of 15-20 micron grain size to obtain the positive electrode particle of 2-5 micron grain sizeParticle, its ratio be the granule contents of 2-5 micron grain size between 5-15%, and the granule content of 15-20 micron grain size is in 30-Between 50%, the particle of 5-15 micron grain size between 25-45%, then and add diameter at 10-15 nanometers, length 10-20The nano-carbon material of micron, nano-carbon material form good conductive network in anode to improve electron transfer rate, improveThe rapid charge characteristic of anode；To graphite cathode particle optimal screening to obtain cathode particle of the partial size at 10-12 microns, and mixThe cathode particle for entering partial size at 3-5 microns is embedded in rate with the lithium ion for improving cathode, while mixing partial size at 23-28 micronsCathode particle, to guarantee the packed density of negative electrode material.
By using above-mentioned technical proposal, the positive electrode particle of 2-5 micron grain size improves positive lithium ion rate travel；5-The positive electrode particle of 20 micron grain sizes guarantees the packed density of positive electrode, so that positive electrode be made to have both quick charge and high energyMetric density characteristic；Nano-carbon material forms good conductive network in anode to improve electron transfer rate, improves anodeRapid charge characteristic.Partial size is embedded in rate in 3-5 microns of cathode particle with the lithium ion for improving cathode, and partial size is micro- in 23-28The cathode particle of rice, to guarantee the packed density of negative electrode material.By adjusting positive and negative pole material particle different specific gravity to protectDemonstrate,prove lithium ion battery tool quick charge and high energy density characteristic.
The utility model has the advantages that the present invention is by adjusting the particle ratio of positive and negative pole material to guarantee that lithium ion battery has quick chargeAnd high energy density characteristic；The present invention by adjusting electrolyte component to improve quick charge when cathode SEI film stabilityAnd conductivity；The present invention by adjusting the porosity of micro-pore septum to improve transmission rate of the lithium ion in diaphragm, to mentionHigh battery core rapid charging performance.
Specific embodiment
A kind of fast charging type lithium ion battery, including nickle cobalt lithium manganate anode and graphite cathode and electrolyte.Fast charging type lithiumWhile ion battery is to improve the quick charge of positive and negative pole material, guarantee higher energy density and preferable circulation againService life.When due to quick charge, rate travel of the lithium ion between battery plus-negative plate is accelerated, in lithium ion from positive deintercalationWhen, it needs quickly to be moved to cathode and insertion is received by negative electrode material, to guarantee that normal charging reaction carries out.It is anti-hereinDuring answering, if the charging current electron transfer rate of battery core application is not achieved in the lithium ion insertion rate of negative electrode material, justLithium metal be will cause in the precipitation of negative terminal surface, the precipitation of lithium metal is irreversible reaction, and the lithium metal of precipitation can not dischargeAnode is migrated back when reaction, so that causing the reversible capacity of battery core reduces.Therefore, to graphite cathode particle optimal screening to obtainPartial size 10-12 microns cathode particle accounting be 40-60%, and mix 10-25% partial size 3-5 microns cathode particle withThe lithium ion for improving cathode is embedded in rate, while mixing cathode particle of the 15-35% partial size at 23-28 microns, to guarantee cathodeThe packed density of material.
Original negative electrode material carries out bonding cathode particle by binder, finds that the content of binder is higher in test, bearsThe higher electron transfer rate for leading to negative electrode tab of the internal resistance of pole piece declines, and the packed density of the active material in cathode is droppedIt is low, therefore, acrylic acid modified butadiene-styrene latex is added in graphite cathode to reduce the content of negative electrode binder, it is only necessary to common fourthThe dosage of Atrolactamide 60-70% can reach identical adhesion strength, and filling out for cathode effective active matter can be improved in this wayDensity is filled, and reduces the internal resistance of negative electrode tab, helps to improve the electron transfer rate of negative electrode tab.
It is excellent to nickle cobalt lithium manganate anode partial size simultaneously in order to make positive electrode have both quick charge and high energy density characteristicChange screening to obtain the positive electrode particle of 2-5 micron grain size, is mixed into the positive electrode particle of 15-20 micron grain size, its ratio be 2-5 micronsThe granule content of partial size is between 5-15%, and the granule content of 15-20 micron grain size is between 30-50%, 5-15 micron grain sizeParticle between 25-45%, then and add diameter at 10-15 nanometers, the nano-carbon material that length is 10-20 microns, nanometerCarbon material forms good conductive network in anode to improve electron transfer rate, improves the rapid charge characteristic of anode.
Nickle cobalt lithium manganate anode graphite cathode between is provided with the micro-pore septum with a thickness of 20-25 microns, by micropore everyThe porosity of film is increased to 47% to improve transmission rate of the lithium ion in diaphragm, to improve battery core fast charge from 40%Energy.
Electrolyte includes comprising 10-20% ethylene carbonate, 10-20% methyl ethyl ester, 14-18% hexafluorophosphoric acidThe electrolyte of lithium, the dimethyl carbonate for adding 50wt% in the electrolytic solution are led due to the high dielectric constant characteristic of dimethyl carbonateCausing lithium hexafluoro phosphate, degree of dissociation is higher wherein, therefore the ionic conductivity of electrolyte can be improved.
In the electrolytic solution be added 1-2% fluorinated ethylene carbonate, fluorinated ethylene carbonate be added after can in SEI film shapeAt more lithium carbonate, positive lithium ion can allow for diffuse through, to improve the rapid charge characteristic of cathode, and improves fastThe stability of cathode SEI film when speed charging.