Lithium Ion Rechargeable BatteriesTechnical Handbook1

Table of Contents1 Overview of Batteries71-1 Foreword71-2 Features71-3 Origin of battery name71-4 Charge/ Discharge mechanism91-5 Cathode91-6 Anode111-7 Battery construction and configuration11〜131-8 Method of manufacture151-9 Environmental considerations152 Battery Characteristics172-1 Charge characteristics172-2 Discharge characteristics172-3 Storage characteristics172-3-1 Self-discharge characteristics172-3-2 Long-term storage characteristics172-4 Charge/Discharge cycle characteristics172-5 Performance data192-5-1 Polymer (UP383562)19〜25Lithium ion rechargeable batteries with lithium cobalt oxide cathodes and graphite anodes1. Charge characteristics; 2. Discharge characteristics;3. Storage characteristics; 4. Discharge characteristics at GSM pulse mode2-5-2 Graphite (US18650GR)27〜31Lithium ion rechargeable batteries with lithium cobalt oxide cathodes and graphite anodes1. Charge characteristics; 2. Discharge characteristics; 3. Storage characteristics2-5-3 Hard carbon (US18650)33〜37Lithium ion rechargeable batteries with lithium cobalt oxide cathodes and hard carbon anodes1. Charge characteristics; 2. Discharge characteristics; 3. Storage characteristics3 Safety393-1 General safety393-2 Safety mechanisms393-3 Procedures to confirm safety and results3-4 Regarding the electrolyte4 Battery Modules41〜4345474-1 Battery modules474-2 Protective circuitry within battery packs474-2-1 Charge voltage regulation494-2-2 Overdischarge voltage regulation494-2-3 Overcurrent regulation494-2-4 Temperature regulation494-2-5 Redundant-protection circuitry494-2-649Chain shortprotection3

4-2-7 Other protective circuitry4-3 Operation of battery packs for PCs4-3-1 Operating range of batteries for power supply systems5 Charging Procedure515151535-1 Recharger voltage per cell535-2 Charge time535-3 Temperature range during charging536 Precautions in Handling and Use6-1 Precautions in handling55556-1-1 Charging556-1-2 Discharging556-1-3 Equipment design556-2 Precautions in use576-2-1 Prohibitions relating to use576-2-2 Charging576-2-3 Discharging576-2-4 Storage576-2-5 Other matters577 Safety Indications597-1 Basic approach to indications597-2 Objects of indications597-3 Means for indications617-4 Matters for indication61〜658 Indications on Acquisition of Safety Certification8-1 Indications for UL1642 lithium batteries standards67678-1-1 Indications on battery pack678-1-2 Indications on equipment using battery pack678-2 CSA and EN standards9 Glossary10 Sales Office6769〜73755

1 Over view of Batteries1–11-1ForewordPortable electronic equipment is moving toward increasing compactness and lightweight, and we are on the threshold of the age of wearable equipment. In suchcircumstances the rechargeable batteries which power such equipment play anincreasingly vital role, and in addition to demands for reduced size and weight, thereare now also requests for performance necessary to support the sophisticatedfunctions of modern equipment. In response to these needs, Sony has conducteddevelopment based on entirely novel concepts, and in 1991 released the world's firstcommercial lithium ion rechargeable battery product. In addition to a high energydensity, this battery also offered excellent low-temperature characteristics, loadcharacteristics and cycle characteristics. As a result, it quickly became anindispensable source of power for audio and video equipment, personal computers,portable telephones, and other portable equipment. And, Sony development effortsare advancing steadily toward the next generation of products, targeting new typelithium ion rechargeable batteries which are easier to use such as "polymerbatteries" with polymerized electrolyte.1–21-2Features1)Energy densities are high; the US18650 size attains the energy density per volume ofapprox. 440 Wh/l and the energy density per weight of approx. 160 Wh/kg.2)Voltages are high, with average operating voltages at 3.6 V for hard carbonbatteries and 3.7 V for graphite batteries; these are approximately three times thecutoff voltage of Ni-Cd and Ni-MH batteries.3)Charge/discharge cycle characteristics are excellent; batteries can be putthrough 500 or more cycles.4)Self-discharge is minimal, at under 10% per month.5)There is no memory effect such as that in Ni-Cd and Ni-MH batteries.6)Remaining capacity can easily be indicated using the discharge curve.7)Carbon material, rather than metallic lithium or lithium alloy, is used as theanode material. The lithium ion state is maintained over a wide range of operatingconditions, for excellent safety.8)In accordance with using gel polymer electrolyte, laminated film can be used toouter equipment and, thin and light lithium ion rechargeable battery wasachieved.*Thickness is approx. 2.5mm at present. In future, achievement of 1mm or lessis possible.*According to using special gel polymer electrolyte, it become possible to supplyno leak of the electrolyte and extremely high safety batteries.*Development of big footprint cells become possible (xx5385 series like as325385 etc.). That was impossible to usual lithium ion batteries.1–31-3Origin of battery nameIn these batteries, carbon material is used in the anodes and a metal oxide materialcontaining lithium is used in the cathodes; lithium ions migrate between the twoelectrodes via an organic electrolyte. By designing these batteries in accordancewith the reversible capacity of the carbon material, lithium does not exist in themetallic state during either the charging or discharging processes.In order to differentiate these batteries from those using metallic lithium or lithiumalloy in the anode, we designated these devices lithium ion rechargeable batteries.7

Charge and discharge mechanism oflithium ion rechargeable batteries Current ElectronsCurrentCathode Li Li Li Li Li Li Li LiElectronsSeparatorSeparatorAnode Li Li Li LiElectrolyte(Polymer battery:gel polymer electrolyte)Discharge1–4 ChargerLoadCathodeAnode Li Li Li Li Li Li Li Li Li Li Li LiElectrolyte(Polymer battery:gel polymer electrolyte)ChargeFigure 11-4Charge/discharge mechanismBattery charging and discharging occur through the migration of lithium ions betweenthe cathodes and anodes and the exchange of electrons through doping and dedoping.More specifically, during charging lithium is dedoped from cathodes consisting of alithium-containing compound, and the interlayers of carbon in anodes are doped withlithium. Conversely, during discharge lithium is dedoped from between the carbon layersin anodes, and the compound layers in cathodes are doped with lithium. Reactionsoccurring in lithium ion rechargeable batteries employing LiCoO2(lithium cobaltate) incathodes and carbon in anodes are shown in Figure1.By means of the initial charging, which takes place during battery manufacture, lithiumions migrate from the lithium compound of the cathode to the carbon material of theanode.initial chargeLiCoO2 C Li1–xCoO2 LixCSubsequent discharge reactions occur through the migration of lithium ions fromthe anode to the cathode.discharge Li1–x dxCoO2 Lix–dxCLi1–xCoO2 LixC charge1–51-5CathodesCompounds containing lithium ions and which can be used as the cathode activematerial must be capable of dedoping lithium during charge, and undergo lithiumdoping during discharge. Candidate compounds include LiCoO2 (lithium cobaltate),LiNiO2 (lithium nickelate), and LiMn2O4 (spinel-structure lithium manganate). Oncomparing the characteristics of these compounds, LiCoO2 was selected for use asthe first generation's cathode active material due to its reversibility, dischargecapacity, charge/discharge efficiency, discharge curve and other properties. Atpresent employing of LiNi CoXO2 was achieved.LiMn2O4 is also being studied.9

1–61-6AnodesIn order to use carbon material in anodes to obtain batteries with a high energydensity, the lithium storage capability of the anode carbon material must beenhanced. Carbon materials with large doping capacities, and the possibility oflithium-carbon intercalation complexes exceeding the LiC 6 stoichiometriccomposition, are being studied.The following three types of carbon material have been employed in anodes.(1) Graphite(2) Graphitizable carbon (soft carbon)(3) Nongraphitizable carbon (hard carbon)In hard carbon, the interlayer distances are large compared with those in graphiteand soft carbon, and reversibility in charging and discharging is good, for excellentcycling characteristics. In addition, floating charge characteristics during chargingare also satisfactory. And such materials have a sloping discharge curve, so that bymeasuring the battery voltage the remaining capacity can be easily determined.On the other hand, graphite materials have a little working voltage by the depth ofdischarge and exhibit excellent characteristics in constant-power discharge. Whenthe lithium ion battery with nickel cathode material and graphite anode is used, suchmaterials have a sloping discharge curve, so that the remaining capacity can beeasily indicated like as hard carbon anode battery.In our research, it was confirmed that lithium in hard carbon and graphitematerials always remains in the ionic state, and does not exist in the metallic state.1–71-7Battery construction and configurationBattery constructions are illustrated in Figure 2.PolymerCathode TabAnode TabTop InsulatorCathodeAnodeAl laminate filmFigure 211

CylindricalCathode leadTop coverSafety vent(PTC)GasketSeparatorInsulatorAnode leadAnode canInsulatorCathodeAnodePrismaticTerminal plateCathode pinCap plateInsulatorInsulator caseSafety ventSeparatorGasketCathode lead Anode canCathodeAnodeFigure 2As for cylindrical and prismatic batteries, sheet like cathodes and anodes arewound together in a spiral shape. Between the cathodes and anodes is wound apolymer separator film which acts to obstruct micropores and interruqt the reactionshould the cell temperature rise excessively for some reason. In order to ensure cellsafety, for example, the cylindrical battery incorporates a safety mechanismconsisting of a circuit breaker, rupture disk, and PTC(possive temperaturecoefficient)device. The electrolyte is an organic solvent which is stable up to highvoltage, in which a lithium salt is dissolved.As for polymer batteries, there are gel polymer electrolyte between cathodes andanodes. Other parts are of very simple constructions.13

1–81-8Method of manufactureIn order to ensure superior characteristics, batteries are manufactured in arigorously controlled environment using carefully maintained equipment.Manufacturing processes can be broadly divided into three stages: electrodematerial production process, assembly process, and charge-discharge process.Electrode production process: The electrode active materials are used to manufacturethe electrode mixtures. These mixtures are then used to uniformly coat both sidesof a thin metal foil. The amount of electrode mixture applied has a considerableinfluence on battery performance, and control of the amount of coated material iscrucial.Assembly process: In batteries where lithium ions figure in battery reactions,elimination of all water content is mandatory. All battery components are driedthoroughly, and batteries are assembled inside a dry room held at low humidity.Charge-discharge process: In the initial charging, lithium ions move from thecathode to the anode, and the device begins to function as a battery. Prior toshipment the discharge capacity is measured, and cells with similar performance arecombined in battery packs.1–91-9Environmental considerationsIn March 1997, Sony Fukushima Corporation(former Sony Energytech Inc.), themain business unit manufacturing lithium ion rechargeable batteries, was the firstcompany in the Japanese battery industry to obtain ISO14001 certification, reflectingongoing efforts to alleviate environmental impact. At present, all Sony business unitsinvolved in the manufacture of lithium ion rechargeable batteries are ISO14001certified, and are promoting activities for the preservation of the global environment.In addition, Sony is conducting development of technology for recycling of lithiumion rechargeable batteries jointly with Sumitomo Metal Mining Co., Ltd., and inApril 1996 announced completion of the world's first recycling system. Subsequentto this, recovery of used lithium ion rechargeable batteries was begun in Japan.Through these activities, Sony is alleviating the environmental burden imposed bylithium ion rechargeable batteries, and is promoting reuse of valuable resources inused batteries15

2 Batter y Characteristics2–12-1Charge characteristicsThe cathode potential is determined by the amount of lithium dedoped from theLiCoO 2 or LiNiCo XO 2 cathode active material. Put another way, if a battery ischarged without setting an upper limit voltage, more lithium ions than are necessarymigrate to the anode, and the battery performance is undesirable for safety reasons.Hence in this battery system, charging is as a rule performed under constantvoltage, constant-current control. The maximum proper charging voltage for Sony'slithium ion rechargeable batteries is 4.2 V.2–2Discharge characteristics2-2The discharge voltage is initially approx. 4 V, and even on average remains high atapprox. 3.6 V for hard carbon batteries and approx. 3.7 V for graphite batteries; thesefigures are three times the values of nickel cadmium rechargeable batteries and nickelmetal hydride rechargeable batteries. Such high discharge voltages are a major featureof lithium ion rechargeable batteries. For instance, when driving equipment with anoperating voltage range of 3 V to 4 V, if using nickel cadmium rechargeable batteries,three cells must be used connected in series, whereas a single lithium ion rechargeablebattery is sufficient to drive the same equipment. In addition, by measuring thedischarge voltage of lithium ion rechargeable batteries combi