Linden D., Reddy T.B. (eds.) Handbook of batteries

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LITHIUM-ION BATTERIES 35.89

LiCoO

Batteries with In-situ Electroplated Negative Electrodes. Solid-state batteries fab-

ricated without a negative electrode material offer performance comparable to SiTON/

LiCoO

cells, the simplicity of fewer manufacturing steps and materials, avoid complications

or irreversible capacity associated with oxide or oxynitride negative electrode materials, and

avoid the limitations of batteries that contain lithium metal. When fabricated, lithium metal

is not present, they can be processed at high temperature. When these batteries are charged,

lithium metal is plated onto the negative current collector, a highly reversible process in

these batteries.

The battery voltage on the initial charge cycle and subsequent discharge at 0.1 mA /cm

1 mA/cm

,and5mA/cm

at 25⬚C is illustrated in Fig. 35.112. As anticipated, the battery

has a voltage characteristic for LiCoO

when cycled versus lithium, and can operate at current

densities comparable to cylindrical C /LiCoO

batteries. The rate capability of batteries with

three different thicknesses of LiCoO

is further illustrated in Fig. 35.113. As shown, the

capacity and rate capability of the cells scales linearly with the thickness of the LiCoO

layer. Discharge at current densities as high as 5 mA /cm

was demonstrated.

The capacity of a thin-ﬁlm LiCoO

battery with an in-situ electroplated lithium negative

electrode cycled at high rate (4C charge, 20C discharge) is illustrated in Fig. 35.114. As

shown, the fade rate was 0.02%/cycle, comparable to that typical for cylindrical C/ LiCoO

batteries cycled at the 1C rate.

FIGURE 35.112 Battery voltage for a solid-state thin-ﬁlm

LiCoO

battery with an in-situ electroplated lithium negative

electrode. (Courtesy of Oak Ridge National Laboratory. Re-

produced by permission of The Electrochemical Society, Inc.

From Ref. 100.)

FIGURE 35.113 Rate capability of a solid-state thin-ﬁlm LiCoO

batteries with in-situ electroplated lithium

negative electrodes. The cells were cycled between 4.2 V and 3.0 V at 25⬚C. (Courtesy of Oak Ridge National

Laboratory. Reproduced by permission of The Electrochemical Society, Inc. From Ref. 100.)

35.90 CHAPTER THIRTY-FIVE

FIGURE 35.114 Capacity of a LiCoO

battery with an

in-situ electroplated lithium negative electrode, normalized

to1cm

and 1

␮

m LiCoO

. The battery was cycled be-

tween 4.2 V and 3.0 V at 25⬚C, charged at the 4C rate and

discharged at the 20C rate. (Courtesy of Oak Ridge Na-

tional Laboratory.)

35.9 CONCLUSIONS AND FUTURE TRENDS

Li-ion batteries have quickly evolved from an R and D interest to a signiﬁcant and growing

fraction of the worldwide battery market. The acceptance of the technology has been driven

by its unique ability to offer a high level of performance in many aspects, including energy

density, speciﬁc energy, rate capability, cycle life, and storage life, in a safe, low cost product.

As costs are reduced, the diversity of available designs increases, and performance improves,

the range of applications addressed with Li-ion batteries is anticipated to increase.

Further improvements in cell performance will be made possible through both more ef-

ﬁcient mechanical designs and improved materials. Li-ion materials are currently a subject

of great interest in the R and D community. Improved positive electrode materials that offer

higher capacity and improved safety properties are in development, as are new negative

electrode materials, such as the tin-based materials, that offer the potential for further im-

provement in speciﬁc energy, energy density, rate capability and longevity.

ACKNOWLEDGEMENT

The author thanks the many individuals and organizations that contributed the data presented

in this manuscript, Jan Riemers, Rick Howard and Jordan Gonchar for their comments, and

Elizabeth Ehrlich for her patience.

LITHIUM-ION BATTERIES 35.91

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36.1

CHAPTER 36

RECHARGEABLE ZINC/ALKALINE/

MANGANESE DIOXIDE BATTERIES

Karl Kordesch and Josef Daniel-Ivad

36.1 GENERAL CHARACTERISTICS

The rechargeable zinc /alkaline/manganese dioxide battery is an outgrowth of the primary

battery. Zinc is used as the negative active material (the anode during discharge), manganese

dioxide for the positive active material (the cathode during discharge), and a potassium

hydroxide solution for the electrolyte.

The original design of this rechargeable battery closely followed the cylindrical inside-

out design of the alkaline primary battery and retained its advantages of long shelf life, good

current density and safety.

This battery was marketed in the mid-1970’s, but only brieﬂy,

for 6-volt lanterns and portable TV sets. Its advantages were its lower cost compared to

other rechargeable batteries and that it was manufactured in a fully charged state. The prob-

lems that limited the commercialization of this design were that the cells were not strictly

zinc-limited and would lose their ability to be recharged due to the expansion of the cathode

if the discharge continued below the voltage level corresponding to a one-electron discharge

of the manganese dioxide (MnO

1.5

). Thus voltage control was needed to limit the discharge

to 1.1 to 1.0 V per cell, depending on the load and age of the battery and the capacity was

reduced because of this higher end voltage. Further, the capability of catalytic hydrogen-gas

recombination was not included in the cell design.

A way to control the cathodic discharge is to limit the capacity of the zinc electrode.

This can, however, cause poor rechargeability of the zinc electrode. Further study of this

battery system led to the development of reliable techniques for limiting the capacity of the

zinc electrode.

2–4

Present-day batteries can be discharged to lower end voltages.

The major advantages and disadvantages of the rechargeable zinc /alkaline /MnO

battery

are listed in Table 36.1.

36.2 CHAPTER THIRTY-SIX

TABLE 36.1 Major Advantages and Disadvantages of Rechargeable Zinc /

Alkaline-Manganese Dioxide Batteries

Advantages Disadvantage

Low initial cost (and possible lower

operating cost than other

rechargeable batteries)

Useful capacity about two-thirds of primary

battery but higher than most

rechargeable batteries

Manufactured in a fully charged

state

Limited cycle life

Good retention of capacity

(compared to other rechargeable

batteries)

Available energy decreases rapidly with

cycling and depth of discharge

Completely sealed and

maintenance-free

No ‘‘memory effect’’ problem

Higher internal resistance than NiCd and

NiMH

36.2 CHEMISTRY

The discharge mechanism of electrolytic manganese dioxide, which is essentially

␥

-MnO

has been studied extensively.

It is generally assumed that the ﬁrst electron discharge step

proceeds in a homogeneous reaction by the movement of protons and electrons into the

lattice, resulting in a gradually decreasing value of x in MnO

from x ⫽ 2tox ⫽ 1.5. The

reaction is a conversion of one solid structure (MnO

) into another (MnOOH), with man-

ganese (formally) in the tri-valent state,

MnO ⫹ HO⫹ e → MnOOH ⫹ OH

Soluble manganese species begin to appear if the discharge is continued, especially when

the lower voltage second-electron range is approached. The manganese ions ﬁnd their way

to the zinc anode increasing the corrosion reaction and reducing the shelf life characteristics.

When electrolytic manganese dioxide is recharged, the process is reversed. The number

of discharge and charge cycles obtainable depends on the depth of discharge, indicating that

irreversible electrode processes are occurring. The relationship between cycle number and

depth of discharge was found to be essentially logarithmic. Coulometric studies indicate that

the recharge efﬁciency reaches nearly 100% after a few cycles. The initial losses are probably

related to ‘‘formation problems’’ as manganese dioxide is a nonconductor and an interface

with the graphite structure must be formed.

The cathode-dominated cycle characteristic of the rechargeable batteries and the logarith-

mic relationship of loss of capacity with cycling are shown in Fig. 36.1. A zinc capacity of

about 2 Ah is usually provided in an AA-size battery to maintain a high ﬁrst-cycle discharge

capacity. This still prevents the MnO

from discharging beyond the one-electron capacity. In

this special experiment the zinc anode is not limiting because only a predetermined capacity

of 1.0 Ah is removed at each cycle until the cutoff voltage of 0.9 V is reached.

Charging of the zinc /alkaline /manganese dioxide battery must be controlled to limit the

charge voltage to 1.65 to 1.68 V. Charging to higher voltages produces a hexa-valent man-

ganate and oxygen gas. The soluble manganate disproportionates into tetra-valent MnO

and

a nonrechargeable divalent manganese species which results in a loss in cycle capacity. The

oxygen gas reacts with zinc to produce ZnO.

The use of special catalysts is now being investigated to suppress the manganate formation

and overcome the poor reversibility of the MnO

discharge. One approach is to use cobalt-

spinel type catalysts.

6–10

Another is to replace the electrolytic manganese dioxide (EMD)

with a specially prepared bismuth-doped form of manganese dioxide (BMD). This modiﬁed

cathode permits a deep two electron MnO

→ Mn(OH)

reversible discharge.

RECHARGEABLE BATTERIES 36.3

FIGURE 36.1 Performance of rechargeable zinc/ alkaline-manganese di-

oxide battery on cycling at 20⬚C: recharging after each discharge. (Courtesy

of Battery Technologies, Inc.)

BMD

EMD

1.9

1.6

1.3

1.0

0.7

0.4

0.1

Electrode Potential, V(Zn/ZnO)

0.5

0.2

-0.1

-0.4

-0.7

-1.0

-1.3

Electrode Potential, V(Hg/HgO)

Discharge Time (hours)

10 20

FIGURE 36.2 Discharge curve for electrolytic Manganese Dioxide (EMD) and Bismuth

modiﬁed Manganese Dioxide (BMD) in KOH. (Courtesy of Rechargeable Battery Corp.)

Bismuth is incorporated as Bi

at about 10 weight-percent of the MnO

. A cathode of

BMD formulated with high surface area, oxidation-resistant carbon can give several hundred

charge-discharge cycles with a depth of discharge equivalent to over 80% of the theoretical

two-electron capacity of the MnO

. The bismuth appears to act as a redox catalyst, extending

the heterogeneous discharge regime as well as blocking the formation of the non-rechargeable

manganese compounds. This produces a markedly ﬂatter voltage discharge proﬁle relative

to EMD and, in addition, a higher capacity as illustrated in Fig. 36.2. The presence of

bismuth is essential in order for the charging to proceed through the reaction sequence:

⫹

1. Bi → Bi ⫹ 3e- (electrochemical)

⫹

2. Bi ⫹ 3Mn → 3Mn ⫹ Bi (chemical)

⫹

3. 3Mn → 1.5 Mn ⫹ 1, 5 Mn (chemical)

Mn in the last disproportionation step recycles to step 2 until charging is complete. Soluble

⫹

Mn and Bi species must be retained at the cathode. Special chemically functionalized

⫹

separators are being developed for the BMD cathode.

36.4 CHAPTER THIRTY-SIX

FIGURE 36.3 AA-size rechargeable zinc / alkaline-manganese dioxide

battery. (Courtesy of Battery Technologies, Inc.)

36.3 CONSTRUCTION

The construction of the cylindrical rechargeable alkaline cell is shown in Fig. 36.3. The

construction is similar to the primary cell, using an inside-out design. The positive electrode

consists of three or four cathodic rings, which are formed under high pressure to a slightly

oversized diameter and then inserted into the steel can. The cathodic mix formulation uses

electrolytic MnO

and 10% graphite. The negative electrode, consisting of a powder zinc

mass containing gelled KOH, is in the center. A nail, located in the center of the gel, serves

as the negative current collector. The cell is crimped-sealed and contains a vent mechanism.

The following features distinguish the rechargeable cell. The cathode contains additives,

such as BaSO

, which increase the cathode capacity and improve cycling. The cathode also

contains a catalyst, such as silver on acetylene black or carbon, to recombine any hydrogen

that may form. The limiting zinc powder anode contains KOH and a gelling agent. The

amount of zinc determines the depth of discharge and thereby the capacity of the cell.

Mercury is not added to the anode and special zinc alloys and/ or organic inhibitors are used

to reduce the zinc corrosion. However, for rechargeable cells, this is not sufﬁcient as the

zinc deposited after the ﬁrst charge is much ﬁner than the original granulated zinc powder.

The silver catalysts added to the cathode recombine the hydrogen that results from the zinc

corrosion. Zinc oxide is dissolved into the KOH to assure that on charge (or overcharge)

only oxygen, but not hydrogen, can be formed by electrolysis. That is, ZnO reduction occurs

instead of the generation of hydrogen. The separator, which is multilayered, contains regen-

erated cellulose with a high oxidation resistance to caustics. It also prevents internal short

circuiting due to zinc dendrite formation.