SONY EXHIBIT 1023
`
`Page 1 of 49
`
`

`
`HANDBOOK OF
`BATTERIES
`
`David Linden Editor in Chief
`
`Second Edition
`
`McGRAW-HILL, INC.
`New York San Francisco Washington, D.C. Auckland Bogota
`Caracas lisbon
`l ondon Madrid Mexico City Milan
`. Montreal New Delhi San J uan Singapore
`Sydney Tokyo Toronto
`
`Page 2 of 49
`
`

`
`Library of Omgress Cataloging-in-Publication Data
`
`Handbook of batteries I David Linden, editor in chief. -- 2nd ed.
`p.
`em.
`First ed. published under title: Handbook of batreries and fuel
`cells.
`Includes index.
`ISBN 0-07-037921-1
`1. Electric batteries--Handbooks, manuals, etc.
`II. Title: H andbook of batteries.
`David.
`TK290l.H36 1994
`621.31 '242--dc20
`
`r. Linden,
`
`94-29189
`CIP
`
`Copyn ght © 1995, 1984 by McGr:nv-Llill. Inc. All nghts reserved. Printed
`in Lhe United States of America. Except as pi.!rmJttcd under rhc United
`States Copynght Act of J 976, no part o f this publicauon IIUIY be
`reproduced or distributed in any form or by DJI)' mean~. or c;tored in <J data
`bnse or rctneval syste m, without the prior wriltcn pemliSSJon o f the
`publishe r.
`The first e dirion was published under the title flandbook of Batteries
`and Fuel Cells.
`
`5 6 7 8 9 0 DOC/DOC
`
`0
`
`ISBN 0-07-037921-1
`
`Tl1c sponsori11g ediwr for this book was 1/oro/tl B. Crnwforcl, tlu: cdtting
`.wpennsor was Fr(llzk Kotowski, Jr., and tile protlucttOII supervisor was
`Suzomte W. B. Rupcaooge It was sec in Tunes Ronum hy tilt! Uniuersitll'S
`Pres.<: (Belfnsr) Ltd.
`
`Printed and bound by R. R. Donnelley & Sons Company.
`
`This book is printed on acid-free paper.
`
`Information contnined in this W(lrk has been obwined by
`McGraw-Hill, Inc. from sources believed to be re liable. I row(cid:173)
`ever, neither McGraw-llill nor its nuthor~ guarantees the
`accuracy or completeness uf any information published he rc111
`and neither McGraw-Hill nor its authors shall he rcsponsibk for
`any errors. omis.~iono; or damage~> arising o ut ol usc of tiJi~
`information. llli~ work i~ published with the understandmg thnt
`McGraw-Hill and its authors arc supplymg inform.Jtio11 bur ore
`not a ttempting to render enginccrin~ Clr mhcr profcssionnl
`servtccs. If such servtccs are required, the as~JstanGc of an
`appropriate professional should be 'lought.
`
`Page 3 of 49
`
`

`
`CHAPTER 1
`BASIC CONCEPTS
`
`David linden
`
`1. 1 COMPONENTS OF CELLS AND BATTERIES
`
`A battery is a device that converts the chemical energy contained in its active materials
`directly into electric energy by means of an electrochemical oxidation-reduction (redox)
`reaction. This type of reaction involves the transfer of electrons from one material to
`another through an electric circuit. ln a nonclcctrochemical redox reaction, such as rusting
`or burning, the transfer of electrons occurs directly and only heat is involved.
`While the term "battery" is often used, the basic electrochemical unit being referred to
`is the "cell." A battery consists of one or more of these cells, connected in series or
`parallel, or both, depending on the desired output voltage and capacity.
`The cell consists of three major components, as shown schematically in Fig. 1.1:
`
`1. The anode or negative electrode-the reducing or fuel electrode-which gives up
`electrons to the external circuit and is oxidized during the electrochemical reaction.
`2. The cathocle or positive electrode-the oxidizing electrode- which accepts electrons
`from the external circuit and is reduced during ' he electrochemical reaction.
`3. The electrolyte-the ionic conductor-which provides the medium for transfer of
`electrons, as ions, inside the cell between the anode and cathode. The electrolyte is
`typically a liquid, such as water or other solvents, with dissolved salts, acids, or alkalis
`to impart ionic conductivjty. Some batteries use solid electrolytes, which arc ionic
`conductors at the operating temperature of the cell .
`
`. The most advantngcous combil'ations of anode and cathode materials are those that
`Will be lightest and give a high cell voltage ::.nd capacity (see Sec. 1.3). Such combinations
`may not always be practical. howevet, tluc to reactivity with other cell components,
`polt~rization. difficully in handling, high cost, and other deficiencies.
`In a practical system, thl! <\node is selected with the following properties in mind:
`efficiency as a 1educing agent, high coulombic output (Ah/g), good conductivity, stability,
`eas~ of fabrication. and low cost. Hydrogen is attractive as an anode material, but,
`obv~ously, must he contained by some means, which effectively reduces its electrochemical
`cqtuvalencc. Practically metals <Ire mainly used as the anode material. Zinc has been a
`pr~dominant nnodc because it hns these favorable proper:ies. Lithium, the lightest metal,
`1~ n.ow becom111g a very attractiVe anode as suitable and compatible electrolytes and cell
`<cs,t?ns have been developed to control its activity.
`fhe cathode must be an efficient oxidizing agent, be st.:ble when in contact with the
`e~cctr~lytc, and have a u. eful working voltage. Oxygen can ~e used directly from ambient
`aJr bemg drawn into the cell, as in the zinc/air battery. However, many of the cathode
`materials arc metallic oxides, while.! oU1er cal hode materials are used for advanced battery
`system:-, giving lugh vol tages and capacity.
`The electrolyte must have good ionic conductivity but not be electrically conductive, as
`
`1.3
`
`Page 4 of 49
`
`

`
`1.4
`
`PRINCIPLES OF OPERATION
`
`Electron flow
`
`Flow of anions
`
`"'
`"Q
`0
`c
`~
`
`Q>
`"0
`0
`-5
`"' u
`
`Flow of cations
`
`Electrolyte
`
`FIGURE 1.1 Electrochemical operation of a ceU
`(discharge).
`
`this would cause internal short-circuiting. Other important characteristics are nonreactivity
`with the electrode materials, little change in properties with change in temperature,
`safeness in handling, and low cost. Most electrolytes arc aqueous solutions, but there are
`important exceptions as, for cxaple, in thermal and lithium anode batteries, where molten
`salt and other nonaqueous electrolytes are used to avoid the reaction of the anode with the
`electrolyte.
`Physically the anode and cathode electrodes are electronically isolated in the cell to
`prevent internal short-circuiting, but are surrounded by the electrolyte. In practical ceU
`designs a separator material is used to separate the anode and cathode electrodes
`mechanically. The separator, however, is permeable to the electrolyte in order to maintain
`the desired ionic conductivity. In some cases the electrolyte is immobilized for a nonspill
`design. Electrically conducting grid structures or materials may also be added to the
`electrodes to reduce internal resistance.
`The cell it elf can be built in many shapes aod conligurations-cylindrical, button, fiat,
`nod prismatic--and the cell components are designed to accommodate the particular cell
`shape. The cells are sealed in a variety o[ ways to prevent leakage and dry-out. Some cells
`are provided with venting devices or other means to allow accumulated gases to escape.
`Suitable cell cases or contajncrs and means for terminal connection are added to complete
`the cell.
`
`1.2 OPERATION OF A CELL
`
`1.2.1 Discharge
`
`The operation of a cell during discharge is also shown schematically in Fig. 1.1. When
`the cell is connected to an external load, electrons ftow from the anode, which is oxidized,
`through the external load to the cathode, where the electrons are accepted and the cathode
`material is reduced. The electric circuit is completed in the electrolyte by the llow of
`anions (negative ions) and cations (positive ions) to the anode and cathode, respectively.
`
`Page 5 of 49
`
`

`
`BASIC CONCEPTS
`
`1.5
`
`The discharge reaction can be written, assuming a metal as the anode material and a
`cathode IDaterial such as chlorine (CI2), as follows:
`
`Negative electrode: anodic reaction (oxidation, loss of electrons)
`
`Positive electrode: cathodic reaction (reduction, gain of electrons)
`
`zn~Zn2+ +2e
`
`Overall reaction (discharge):
`
`1.2.2 Charge
`
`During the recharge of a rechargeable or storage battery, the current flow is reversed and
`oxidation takes place at the positive electrode and reduction at the negative electrode, as
`shown in Fig. 1.2. As the anode is, by definition, the electrode at which oxidation occurs
`and the cathode the one where reduction takes place, the positive electrode is now the
`anode and the negative the cathode.
`In the example of the Zn/Cl2 cell, the reaction on charage can be written as follows:
`Negative electrode: cathodic reaction (reduction, gain of electrons)
`
`Zo2 + +2e~Zn
`
`Positive electrode: anodic reaction (oxidation, loss of electrons)
`> Cl2 + 2c
`
`2Cl-
`
`Overall reaclion (charge):
`
`.=....
`
`DC
`power supply
`
`+ 1-
`
`-r - -
`,____
`
`Q>
`"0
`0
`£. ;
`
`(.)
`
`Electron flow
`
`+
`r-.._
`
`1--
`
`Q>
`
`'8
`c
`~
`
`Flow of anions
`
`Flow of cat•ons
`
`-
`
`....____
`
`Electrolyte
`
`FIGURE 1.2 Eledrochemic:al operation of a cell
`(charge).
`
`Page 6 of 49
`
`

`
`'
`
`- W flithittm in aqtleour. solutions requires the use of tton:t(.tttcous electrolytes
`r<.‘:ictw1 /[l1(_i[iC httltetics.“ Polar Organic liquids are the most contmtm e.|eclt'olyte
`mm hm active pI'imaty cells, except for the lhionyl chloride [SDC|3) and sult'ttI'yl
`' Em
`cells, where these ii10t'ganic compounds serve as both the soiveltt and the
`(SO;-113)
`idc
`material. The important properties of the electrolyte are:
`hotlu
`< iv‘: cal.
`l|.‘i
`
`I
`
`ltydrugen atoms, allholtglt
`
`ilEt\I't! no reactive prolotts or
`that is,
`133 aprolic,
`1 atoms may he tn Ihs: molecule.
`mi bu n|J[11'EE1l.TliVC with lithium (or l’ot'm a [.it‘otcctive coating on the lithium surface
`2_ Itri1t|:W.,1t further reaction) and the l.':£1ll‘t0dC.
`1” PIL1 be capable of Forming an clectmlytc of high ionic contlttctivity.
`- H mm Id be liquid over :1 broad tctnpcrtiturc rangtr.
`‘
`ha
`it film”
`vt: favorable pliysical t.‘liat‘nctc1'istit:s, sttcll as low vapor pressttte, stability,
`,hould
`.
`.
`:1
`'
`'
`llujllfl-{City-,
`'[_lr1'nl nonllamtnahtlity.
`5.
`the organic stilvenls colttmonly used it1 lithium. btlttcries; is given in Table 1-1.5.
`A iissina of
`.. m-garlic electrolytes, as well as lhionyl chloritlc {nip ~ Iil5°C, hp 7R.8"C) tutti sttlfuryl
`_
`,
`ll1¢55“,’|, (mp —54"C, hp 59.1“C), are liqtticl over :1 wide temperature range willt
`low
`Cllioriib
`ninth‘. This clint'actct'istic provides the potential
`for operatiorl over a wide
`"licwmfimfi-2 range, petrtictlituly at low len1pet'atures.
`lwfizlliiuni salts,-sunzlt as I.iCL LiCID,,, LiBr.
`l.iCF_.SO_., and LiAlCl,,, arethe electrolyte
`I most cornrnoniy used to provide ionic conductivity. The solute must be able to Iforrn
`electrolyte which does not react with the active cleclrotlu rnalcrials.
`It must be
`mluble in lhc orgatlic solvent and dissociate to form a cuntluctiue electrolyte solution.
`-M-‘1_I;i1'l]l.1I!‘l conductivity ‘is normally obtained with a 1-molar solute concentration, but
`umcyalty the conductivity of these electrolytes IS about one-tenth that of the aqueous
`;v5;g.n1s. To accommodate this lower conductivity, close electrode spacing and cell designs
`to minimize impedance and provide good power density are used.
`
`
`
`41.4-rAg2L,ru4—>LIZLIU41-Aug
`
`.1./1..u
`
`595.4
`
`181.9
`
`A:°>2V40t1* V205
`
`l'\52\./L\./4
`
`
`
`
`
`*Multiple-stepdischarge;seeRef.9,
`
`14.2.4 Cells Couples and Reaction Mechanisms
`The overall discharge reaction mechanism for the various lithium primary batteries is
`shown in Table 14.4., which also lists the theoretical cell voltage of each cell. The
`’ mechanism for the discharge of the lithium anode is the oxidation of lithium to form
`lithium ions (Li+) with the release of an electron,
`Li—> Li+ + e
`
`The electron moves through the external circuit to the cathode, where it reacts with the
`cathode material, which is reduced. At the same time the Li+ ion, which is small (0.06 nm
`in radius) and mobile in both liquid and solid-state electrolytes, moves through the
`electrolyte to the cathode, where it reacts to form a lithium compound.
`A more detailed description of the cell reaction mechanism for the different lithium
`primary batteries is given in the sections on those cell systems.”
`
`14.3 CHARACTERISTICS OF LITHIUM PRIMARY
`
`__BA1TERIES
`14-3-1 Summary of Design and Performance Characteristics
`A listing of the major lithium primary cells now in production or iil.i\'Ei]'|CCLi tlevelopment
`$13“ ? Summary of
`their co_nsti'ttctionaI
`featt1t'cs.
`ltcy clectriczil
`c|tat'actei'i.~:tiCS. and
`chargciticttlrers are presented In Table l_4.tJ.
`the types _ol. cells.
`their sizes. and some
`eristtcs are subject to chatigc (.llJ]'lCl!LiIl1g on cell design, sta11clat'tltzal|ot1_. and rnarkcl
`
`Page 7 of 49
`
`

`
`36.4
`
`ADVANCED BA'n'ERY SYSTEMS
`
`36.2 CHEMISTRY
`
`lltc objective or the rechargeable lithium bauery program is to develop b~
`high energy den. ily, htgh power density, good cycle life and charge rctcnt~s that ha,.
`provide this high performance reliably and safely. The selection of cell corn 100
`• and 1~
`designs i~ !tcccssarity. a. t:t>mpromise. lO nchi~vc. the optimum balance. r-..fa'~lcntl. an~
`charactensttcs and cntena fot sclcctton arc stmtlar to those for primary litl/ or the
`covered in Chap. 14. The process, however, is even more complex for rc ~urn ceu~
`hatter ies as the cell chemistry mus t be reversible and the reactions that oc c argcablc
`recharge a[cct all of the ch(lracteristics and the performance on subsequent cyc~ur during
`The different types of lithium rechargeable bHl!eries identified in Pig. 36'~g.
`· call be
`classified conveniently into five ca tegories:
`
`1. Solid-cathode cells using intercalation compounds (or the postlrve electrode
`.
`.
`' a hqu,d
`organic electro lyte, a nd a metallic lithium negative electrode.
`
`2. Solid-cathode cells using intercalation compounds for the positive electrode a
`electrolyte, and a metallic lithium negative electrode.
`'
`
`1
`po Yrncr
`
`3. Cells using intercalation compounds for hoth the positive ~nd the negative ele t
`and a liquid or polymer electrolyte (lithium-ion cells).
`c rode\
`
`4. lnurgan.i~ electrol~te. cells, which use the ele~trolyt: solvent ?r a s~li~ redox couple for
`the poslttve and hthtum metal for the negattve active matenal. (L1thmm-ion type Cell
`have also been investigated with inorganic electrolytes.)
`s
`5. Cells with lithi~m-a.lloy a~odes, liquid org~nic or polymer electrolytes, and a variety or
`cathode matenals, mcludmg polymers. Thrs technology has been used mainly in small
`fiat or coin cells.
`
`The components and reactions of typical examples of these types of rechargeable
`lithium batteries are summarized in Sec. 36.3.
`
`36.2.1 Negative Electrodes
`
`Typical negative electrode materials for rechargeable lithium batteries are listed in Tahle
`36.2. Of these, lithium is the lightest and most electropositive, and it has a high specilic
`capacity, 3.86 Ah/g. it is also more easily handled than the other alkali metals.
`
`TABLE 36.2 Negative Electrode Material
`
`Material
`
`Li metal
`LiAI
`
`Li0 5C',. (coke)
`LiC .. (doped coke or graphite)
`LiW02
`LiMo02
`LiTiS1
`
`Voltage range
`vs. lithium,
`v
`
`0.0
`0.3
`
`0,0- 1.3
`0.0- 0.5
`0.3- 1.4
`0.1-1
`l .4
`1.5-2. 7
`
`Theoretical
`specific capacity,
`Ah/g
`
`3.86
`0.8
`
`0.185 }
`0.370
`0.12
`0.199 }
`0.226
`
`------------------ -----
`
`Comments
`f ·r
`d•'ly availahk
`. 1 .
`Lll IIUIII 01 s rea
`Generally brittle foils,
`difficult
`I. h.
`-00 cells
`Used or 11 tum-•
`f
`
`·011 cell'
`.
`.
`Possible for hthtum-t
`(rocking chair)
`
`Page 8 of 49
`
`

`
`RECHARGEABLE LITIIIUM BATTERJES
`
`36.5
`
`While metallic lithium has the highest specific capacity, it is more reactive than
`lithium-aluminum and other alloys. These are used mainly in mall Rat or coin cells. as it is
`difficult to scale up to larger and spiraUy wound designs because most lith1um alloys are
`brittle and cannot be rolled easily into thin foils. 1\nolher approach is the usl! of a carb<>n
`material for the negative electrode. T hese are 'lllractive from a safety viewpoint as reactive
`metallic lithium is not present in the cell. A suitable intercalation compound is selected for
`the positive electrode for these cells so that a reasonable ceJI voltage is obtained. The cell
`operates by the lithium ions shuttling back and forth between the electrodes during the
`discharge-charge cycle. This accounts for the term "rocking chair" that is applied to this
`technology. No metallic lithium is plated during the charge and no metallic lithium is
`present in the cell.
`
`Lithium Metal. The search for high-energy-density batteries has inevitably led to the use
`of lithium, as the electrochemical characteristics of this metal are uniquely suited. A
`number of cells, both primary and rechargeable, using a lithium anode in conjunction with
`intercalation cathodes, were developed whkh had attractive energy densities, excellent
`storage characteristics, and, for rechargeable cells, a reasonable cyde life. Commercial
`success has eluded all but the primary and small rechargeable cells due to persistent safety
`problems.
`The difficulties associated with the usc of metallic lithium stem from its reactivity with
`the electrolyte and the changes that occur after repetitiv~ clJaige-dischargc cycling. When
`lithium is electroplated, during recharge, onto a metallic lithium electrode, it forms a more
`porous deposit with a larger surface area than the original metal. While the thermal
`stability of lithium metal foil in many organic electrolytes is good, with minimal exothermic
`reaction occurring up to temperatures near the melting point of lithium (181°C), after
`~ycling the surface area of the lithium increases significantly with a corresponding increase
`m the reactivity. This lowers the thermal stability limit of the system, with the result that
`cells become increasingly sensitive to abuse as they are cycled.
`. _Another contributing effect is the inability of attaining 100% lithium cycling efficiency.
`fh1s happens because lithium is not thermodynamically stable in the organic electrolytes
`and the surface of the lithium is covered with a film of the reaction products between the
`li~hium and the electrolyte. Every time the lithium is stripped and replated during
`~ascharge Hnd charge, a new lithium surface is exposed and then passiv<Hed with a new
`·~lm, consuming lithium. Therefore in order to obtain a reasonable cycle life, o three- to
`hvefoJd excess of lithium is required.
`The failure to control the surface area of the lithium anode rcmnins a problem, limiting
`h
`t e commercialization of lithium anode cells with liquid organic electrolytes. Given this
`pr~blem, an alternate solution is to use an electrolyte, such as a solid polymer electrolyte,
`Whtch is less reactive with lithium. This is covered in Sec. 36.2.3.
`
`Carbon Materials.
`In the lithium-ion cell, carbon materials, which can reversibly accept
`and donate ignificant amounts of lithium (Li: C = 1: 6) without affecting their mechanical
`ana electrical properties. are uscu for the anode instead of m etallic lithium. Carbon
`ralerial can be used as an anode in lithium-ion cells since the chemical potential of
`~~hiated carbon material is almost identical to that of metallic lithium, as shown in Fig.
`;1 .2. ihus nn electrochemical cell made with a lithiated carbon material will have almost
`,~c $iame open-circuit voltage as one made with metallic lithium. In practice, the lithium(cid:173)
`In~ Cell is manufactured in a fully discharged state. Instead o f using lithiated carbon
`h;llenat, which is air-sensitive, Lhc anode is made with carbon and lithiation is carried out
`8llbscquently charging the cell.
`Ca l~lc spccafic energy or capacity of the lithium-ion system depends largely on tbe type of
`:t/'}\~n materials used, Lhc litlrium intercalation efficiency, and the irreversible capacity
`c~li<>caatcd with the first charge process. Table 36.3 lists the properties of some of these
`a/bon materials. It has been found that coke type carbon, having physical properties such
`ash content < 0.1%, surface areu < 10m2/g, true density <2.15g/cm3
`, and interlayer
`
`Page 9 of 49
`
`

`
`36.6
`
`ADVt\• CEO BATI'ERY SYSTEMS
`
`5.
`
`_J
`"' 3
`>
`
`Tu.wo2
`1 L iAI
`
`0
`
`Li metol
`
`I
`Li qrophite
`
`5
`
`0
`
`t'IGURE 36.2 E lectrochemical potential of some Li(cid:173)
`intt;rcalation compounds vs. L1 metal PPY = polypyrrolc.
`polyviu)'l furan.
`PVJ·
`
`spacing > 3.45 A, is suitable for the lith ium-ion system. These types of carbon mate .
`1
`can provide about 185 mAh/g capacity (correspondmg to LiC12 ). Figure 36.3 shows~~ s
`carbonization process for graphitizable organic malerials. By controlling the tcmperatu c
`of the heat treatment, carbon material having specific properlies s uch as dcnsit)' a:~
`inte rlayer spacing can be prepH rcd. D oping witl1 nitrogen, boron, or phosphorus can
`increase the capacity o f coke type materials to 370 mAh/g. Graphitic carbons having an
`interlayer spacing of 3.36 A can deliver 370 rnAh/ g capacity in some selected electrolyte),
`1l1c amount o f e<tpacaty delive red by diCferent type~ of carbon materials, including natu1aJ
`and synthetic graphite, in ethyle ne carbonate-based e lectrolytes o n the first discharge is
`shown in Fig. 36.4.2 TW figure shows lhe advantage o f the graphite materials, which have
`a flan e r discharge and a higher capacity than the coke materials. App•·opriate solventli,
`bowever, have to be ~elected with present-day graphit e materials to avoid electrolyte
`decompositio n.
`During the first electrochemical intercalation of lithium into the carbon, some litl1ium
`is irreversibly consumed and a
`ignificant amount of capacity cannot be recovered in
`the following discharge. Ftgures 36.5 and 36.6 show the voltage profile of the first charge
`and discharge of petroleum coke and graphite electrodes versus a lithium electrode.
`
`TABLE 36 .3 Physical Properties of Coke and Graphite Anodes for Lithiutn-Ion Cells
`
`Item
`
`Type
`
`Structure
`Physical paramett.!rs:
`lnterlayer spacing d002, A
`Crystalline sib.! /.,, A
`Surface area, m 2/g
`De ns ity, g/cm 3
`A sh content, %
`
`Coke
`
`Pelt oleum
`coke
`D isordered
`
`G raphite
`JsolO[>IC, Naturill
`Synthetic, Syn thetic,
`KS-15
`KS-44
`EC-110
`Ordered layer structure
`
`3.46
`46
`6
`2.14
`0.{)8
`
`335
`900
`14
`2.255
`0.05
`
`3.35
`>1000
`10
`2.24R
`··.::0. t
`
`3.34
`>1000
`10
`
`3.34
`::->200(1
`
`----
`
`Page 10 of 49
`
`

`
`RECHARGEABLE LITHIUM BA'ITI::.KIES
`
`36.7
`
`~ (X):) =!!.
`C0):;~-500°C
`etc.~-1000~
`Aromatic hydrocarbon 0:X)
`
`Pitch
`
`z
`
`Carbon
`
`FIGURE 36.3 Schematic diagram of tbe carbonization process for a graphitiwble organic
`material.
`
`respectively.3 This irreversible capacity, which uepem.ls on the electrolyte solution and the
`type of carbon material, is explained on the basis of the reduction of the electrolyte
`solution and the formation of a passivating film at the Li_,C interface.• When the film is
`sufficiently thick to prevent electron tunneling, the electrolyte reduction is suppressed and
`the electrode can then be cycled reversibly. The first step is, therefore, critical in order to
`obtain a uniform passivating film. Chemical combination of lithium to Lhe surface
`functional group of carbon may also play an important role in this irrcver ible capacity.
`Very little loss usually occurs after the first intercalation. The capaci ty o n the second and
`s~bsequent cycles is abat1t the same, and the lithium intercalation during charge and
`discharg,e is nearly 100% reversiblt a~ ~huwn in Fig. 36.15.
`The value of the diffusion coefficient of the lithium ion in the carbon electrode varies
`With the extent of Iithiation o f the carbon electrode. The diffusion coefficient for the
`petroleum coke (Li .. C6) electrode is shown in Fig. 36.6.5 The value of the diffus io n
`6 The diffusio n steps are critical
`~Oefficient of lithium ion in graphite is about 10 11 cm2 s 1
`•
`tn the intercala tion process.
`The theo re tical capacity of metallic lithium is much higher than that of lithiated carbon
`~a~etial having a composition o f LiC6 • The advantage of the higher capacity of metallic
`lithtum d im inil-.hC$ significantly because a three- to fivefold excess of lithium is required in
`
`2.5
`
`2.0
`
`£
`_J 1 5
`......
`
`w
`
`Artif icol
`graphite
`
`Pitch
`coke
`
`PetroiE!I.Im
`
`ooko \v.:::::>---
`
`0. 5
`
`/~"
`~.>,.,..
`0~~~==~==~~~
`0
`100
`200
`300
`4 00
`Discharge capacity, mAh/g
`
`FIGURE 36.4 first discharge curves of carbon materials
`
`Page 11 of 49
`
`

`
`36.8
`
`ADVANCED BATfERY SYSTEMS
`
`2
`
`~ 1.5
`+
`J .....
`:J
`"' >
`0 +
`t a..
`
`.5
`
`c
`
`First dischan~e
`
`0 c_ __ L_~L---L-~--~~~--~--~
`0
`50 100 150 200 250 300 350 400
`Copoclty, mAh/ Q
`( a)
`
`2
`
`> . + 1, 5
`:J ' ::l
`
`.;
`>
`c
`
`+= c t
`
`~
`
`. 5
`
`Fi rst
`dlschon;~e
`
`tOO 150 200 250
`Capacity, mAh / Q
`( b )
`
`FI GURE 36.5 Representation of irreversible capacity as(cid:173)
`sociated with the first charge/discharge process. (a ) Co ke.
`(b ) Artificial graphite.
`
`0 .3
`0.4
`x in u.c6
`FIGURE 36.6 Variation of diffusion coefficient of lithium ion
`with lithium intercalation in petroleum coke carbon.
`
`0 .5
`
`0 .6
`
`0.7
`
`Page 12 of 49
`
`

`
`RECH ARG EABLE LITHIUM BATTE RIES
`
`36.9
`
`TABLE 36.4 Comparison of Usable Specific Capacity (Ah/kg) and
`Capacity Density (Ah/L) for Lithiated Carbon vs. Lithium Metal
`Anodes
`
`Characteristics
`
`Theoretical specific capacity, Ah/kg
`Theoretical capacity density, Ah/1
`Practical specific capacity, Ah/kg
`Fourfold excess of lithium
`95% active material in carbon electrode
`Practical capacity density, Ah/L
`Fourfold excess of lithium
`Porosity of carbon electrode (50%)
`
`*Density of lithium= 0.53 g/cm3
`
`•
`
`Li metal
`
`3862
`2047*
`
`966
`966
`
`512
`512
`
`372
`837
`
`372
`353
`
`837
`418
`
`rechargeable batteries h aving metallic lithium anodes to achieve a reasonable cycle life.
`The comparison is sh own in Table 36.4.
`
`Transition Metal Compounds. Transition metal compounds having layered structures
`into which lithium ions can be intercalated and deintercalated during charge and discharge
`and electrochemical potentials close to those of lithiated carbon m aterials can also be used
`a~ the negative electrod e in lithium-ion cells. (To d istinguish them from the lithiated
`carbon cells, cells using the transition m etal compounds for the negative electrode m ay be
`rderrcd to as rocking-chair cells.) F igure 36.2 shows the electrochemical potentials of
`s~me lithiated transition metal compounds. The electrochemical potentials of Lix W02,
`Ll, Mo02, and Li,, TiS2 are close to that of lithia ted carbon and distinctly different from the
`values for Li .. Mn20 ,., Li,.Co0 2 , and LixNi02 • WO.h Mo07 , or TiS2 can then be used as
`anodes and LiMn20 4 , LiCo02 , or LiNi0 2 as cathodes. Cells of these types have been
`developed using TiS2 anodes and LiCo02 cathodes in an organic electrolyte.7
`
`36·2.2 Positive Electrodes
`~~ere is a relatively wide choice of materials Uull can be selected for the posiuve
`~ Cctrodcs o f lithium bauedcs. However. many of the e, which involve reactions which
`r~ak and rearrange bonds during discharge, cannot he readily reversed and are limited to
`~~~tnary nonrechargcabl~ batteries. The best cathoues for rechargeable batteries arc Lhose
`dis ere there is little bonding and structural modificatio n of the active mate rials during the
`chargc~ha rgc rcaction .11
`:~fercalation Compounds. The insertion or intercalation compounds arc among the most
`in~Lnble catho de materials. In these compounds, a guest species such as lithium can be
`uu ~rtcd imerstitinlly inLO the host lauicc.: (during discharge) and subsequently extracted
`~:~g ~ecbargc with lillie or no structural modification of the host.
`l e Intercalation process invo lves three principal steps:
`l. D·ff
`1 Usion o r migra tion of solvated u + ions
`~
`3' Desolvation and injection of Li + ions into the vacancy structure
`. Diffusion of u + ions into the host str ucture
`
`'the electrode reactions which occur in a Li/Lix (HOST) cell, where (HOST) is an
`
`Page 13 of 49
`
`

`
`36.10
`
`ADVANC~D 13A"ITERY SYST EMS
`
`inlercalation cathode, arc
`
`yLi H yLi ' + ye
`yLi ' + ye + Li..(HOST) H Li,, _,.(HOST)
`
`at the Li metal anode
`at the cathode
`
`lead ing to an overall cell reaction of
`
`y Li -1 Li,(HOST) H Li, I ... (I lOST)
`A numbe r ?r. ~actors ha~e to he c?nsidere~ in the cho ice of th~ in_tercalati(ln c
`such as rcvcrstbthly of the mterca lotto n reacllon, cell voltage, vanat1on of the v ~rnpound
`the state of charge, and availability a nd cost of the compound. T able 36.S li~t.slagc With
`lhe kuy
`requireme nts for
`inte rcala tio n mat..;ria ls a m.l Table 36.6 presents 50
`the
`char acLcrislics of lhc intercala tion and o the r compounds that have been usc~n_c ~r the
`rechaigeable cells. The ~le~trochcmical po te ntia ls .or. sever al lithium intcrcala::~ hthiutn
`pounds versus those or hth1um metal and tbe van a110n of voltage with lhc a n Cotn.
`inter calation arc shown in Fig. 36.2.
`mount ()f
`
`TABLE 36.5 Key Requirements for Positive-Electrode Intercalation
`:Ylaterial (Li.~MO,) Used in Rechargeable Lithium Cells
`
`H igh free energy of reaction with lithium
`Wide range of x (amount o( intercalation)
`Little structural change o n reaction
`Highly reversible reaction
`Rapid diffusion of lithium in solid
`G ood electronic conductivity
`No solubility in electrolyte
`Readily available or easily synthesized from low-cost reactants
`
`TABLE 36.6 Positive-Electrode Materia ls and Some of Their Characteristics
`
`Average
`voltage
`vs. lithium,*
`v
`
`Lithium/
`mole
`
`Practical
`specific
`encrgy,t
`Wh/kg
`
`Comments
`
`Material
`
`MoS2
`M n0 2
`TiS2
`NbSe3
`LiCo02
`LiNi02
`LiMn2 0 4
`
`v bol3
`V20~
`so2
`
`CuCI2
`
`Polyacetylene
`Polypyrrole
`
`1.7
`3.0
`2 .1
`1.9
`3.7
`3.5
`3.8
`
`2.3
`2.8
`3.1
`
`3.3
`
`3.2
`3.2
`
`0.8
`0.7
`1
`3
`0.5
`0.5
`O.R
`
`2.5
`1.2
`0.33
`
`230
`650
`550
`450
`500
`480
`450
`
`300
`490
`220
`
`660
`
`340
`280
`
`Naturally occurring
`Inexpensive
`Costly
`Costly
`Good for lithium-ion system
`Good for lithium-ion system
`Good for lithium-ion system,
`inexpensive
`Good for SPE system
`Good for SPE system
`Toxic e lectrolyte; good for pulse
`power applications
`Toxic e lectrolyte· oood for pulse
`'"'
`power applications
`FM polymc1 ckctrodcs
`For polymer electrodes
`
`---
`
`'' AI low rates.
`t Based on cathode material only and avcrag..; voltage ;ontl lithium/mole as shown.
`
`Page 14 of 49
`
`

`
`RECHARGEABLE LITHIUM BATTERIES
`
`36.11
`
`TransitiOn metal oxides (Mn02 , LiCo02 , LiNi02 , V60 13) , sulfides (MoS2, T iS2), and
`selenides (NbSe3) are used in rechargeable lithium batteries. The lithiated transition metal
`oxides (such as LiCo02, LiNi02, and LiMn20 4) are attractive materials used as the
`cathode in the Jitbium-ion rechargeable cell. LiCo02 and LiNi02 have a layered structure,
`where lithium and transition metal cations occupy alternate layers of octahedral sites in a
`distorted cubic close-packed oxygen-ion lattice. The layered metal oxide framework
`provides a two-dimensional interstitial space, which allows for easy removal of the lithium
`ions. The layered structure of LiCo02 and LiNi02 can be prepared by high-temperature
`treatment of a mixture of lithium hydroxide and the metal oxide in air,9
`
`Co20 3 + 2LiOH
`
`7()(J"C
`
`2LiCo02 + H20
`
`NiO +2LiOH
`
`700"C
`
`LiNi02 + H20
`
`Spinel LiMn20 4 may be obtained by heating a mixture of appropriate amounts of Li2C03
`and Mn02 at 800°C in air.5
`10 The LiMn20 4 spinel framework possesses a three(cid:173)
`'
`dimensional space via face sharing octahedral and tetrahedral structures, which provide
`conducting pathways for the insertion and extraction of lithium ions.
`The removal and insertion of the lithium ion for the three lithiated transition metal
`oxides are
`
`LiCo02 H Li1-xCo02 + xLi 1 + xe
`LiNi02 HLi1_xNi02 +xLi+ +xe
`LiMn20 4 H Li1-xMn20 4 + xLi·' + xe
`The reversible value of x for LiCo02 and LiNi02 is less U1an or equal to 0.5, and the value
`IS greater Lhan or equal to 0.85 Cor lithiatcd m anganese oxide. T hus although the
`theoretkal capacity of LiCo02 and LiNi02 (274 mAh/g) is almo~t twice as high as that of
`LiMnl 04, the reversible capacity of the three cathode materials is about the same
`(135 mAh/g). In the long run it is expected that the manganese-based compounds will
`become the material of choice as they are more abundant, less expensive, and nontoxic.
`Figure 36.7 compares the reversible discharge capacity of the three cathode materials. It is
`10 ~e noted that lithium-ion cells made with LiMn20 4 require a higher charge voltage to
`ilch•eve full capacity.
`
`4"'---..... ______ _
`
`--- ---.---
`
`- - - -
`
`--------
`=---.:::-:_:-.=-~ 'r- - -
`\
`
`\
`
`I
`
`:>
`~
`0> E 2
`~
`
`LiCo02 charged at 4 0 V
`- LiN iOz charged at 4.0 V
`- - -
`------ LiMnz04 chorgedat42V
`- - - LiMnz0 4 charged at 4.5 V
`
`----
`
`-......,
`
`""