This document provides information about different types of batteries. It begins with an overview of the basic electrochemistry involved in batteries, including the components (electrolyte, anode, cathode, container) and redox reactions. It then discusses various primary (non-rechargeable) batteries like zinc-carbon, silver oxide, and alkaline batteries. Rechargeable batteries covered include nickel-cadmium (Ni-Cd), nickel-metal hydride (Ni-MH), lead-acid, and lithium-ion. Specifications discussed are voltage, size, capacity (amp-hours), and rechargeability. Concerns with different battery types like toxicity (cadmium) and memory effect are also summarized.

1. 14. Batteries Technology
gy

2. Outline
„ Intended to provide basic information about
variety of batteries available
y
„ Contents:
„ Basic Electrochemistry
„ Basic Electrochemistry
„ Battery Types
„ Specifications and Main Concerns on Batteries
„ Specifications and Main Concerns on Batteries
„ Rechargeable Batteries
„ How to choose batteries?
„ How to choose batteries?

3. What’s battery
„ Battery is an electrochemical cell that can
convert chemical energy in electrical energy
convert chemical energy in electrical energy
(redox reaction)
It i t f 4 i t
„ It consists of 4 main parts:
„ Electrolyte
„ Anode
„ Cathode
„ Cathode
„ Container

4. Electrolyte
„ Electrolyte can provide electrically conducting
solution when dissolving in water. (adapted from Ebbing,
General Chemistry 5th Ed )
General Chemistry - 5th Ed.)
„ Generally, substance or solid that dissolves in
aqueous form (ionic solution) is electrolyte
aqueous form (ionic solution) is electrolyte
„ Example: Potassium hydroxide (for Ni-Cd
battery) sulfuric acid (for Acid battery)
battery), sulfuric acid (for Acid battery).
„ The chemical reaction (redox reaction) to produce
electrical energy takes place in electrolyte in a
electrical energy takes place in electrolyte in a
battery

5. The Chemical Process – Redox
Reaction
„ The chemical process occurs in a battery is redox
reaction (Double “oxidation-reduction” reactions)
( )
„ Redox Reaction
„ Chemical reaction involves electron (or ionic) transfer
„ Chemical reaction involves electron (or ionic) transfer
between reactants
„ Example:
p
It can be described in 2 half-reactions – oxidation and
reduction reactions )
(
)
(
)
(
)
( 2
2
s
Cu
aq
Fe
aq
Cu
s
Fe +
→
+ +
+

6. Redox Reaction
Oxidation half reaction where a species loss electrons
„ Oxidation – half-reaction where a species loss electrons
„ Reduction – half-reaction where a species gain elections
E l
„ Example:
„ Oxidation (Fe lost e-):
„ Reduction (Cu2+ gained e-):
„ Reduction (Cu gained e ):
Oxidation
)
(
)
(
)
(
)
( 2
2
s
Cu
aq
Fe
aq
Cu
s
Fe +
→
+ +
+
Reduction
Reduction
−
+
+
→ e
aq
Fe
s
Fe 2
)
(
)
( 2
)
(
2
)
(
2
s
Cu
e
aq
Cu →
+ −
+
)
(
2
)
( s
Cu
e
aq
Cu →
+

7. Anode & Cathode
„ Anode
O id ti ti t k
„ Cathode
„ Oxidation reaction takes
place
Losing electrons
„ Reduction reaction takes
place
„ Losing electrons
„ “Positive” terminal of a
battery
„ Gaining electrons
„ “Negative” terminal of a
b tt
battery battery

8. Basic Electrochemistry
„ Electrochemical Cell
„ A system consists of electrodes that dipped
„ A system consists of electrodes that dipped
into electrolyte, which allows chemical
reactions to generate electric current
reactions to generate electric current

9. Electrochemistry Example –
Daniell Cell
Voltaic Cell

10. Types of Batteries
ƒ The primary battery converts chemical energy to
electrical energy directly, using the chemical
materials within the cell to start the action.
ƒ The secondary battery must first be charged with
electrical energy before it can convert chemical
energy to electrical energy. The secondary battery
is frequently called a storage battery, since it
stores the energy that is supplied to it.

11. Battery Types
„ Primary battery
Non e h ge ble
„ Non-rechargeable
„ Non-reversible chemical process
E ample Zn C Li Iodine Alkaline batte ies and
„ Example: Zn-C, Li-Iodine, Alkaline batteries and
Silver Oxide Cell
Secondary battery
Secondary battery
„ Rechargeable
„ Reversible chemical process
„ Reversible chemical process
„ Example: Ni-Cd, Ni-MH, Lead-acid, Li-Ion
batteries

12. Basic Structure of Primary
Basic Structure of Primary
Battery – Zinc-Carbon Dry Cell
„ Most fundamental battery.
„ Anode: Zinc powder
„ Cathode: Graphite (Carbon), ZnCl2,
M O NH Cl
MnO2, NH4Cl
„ Electrolyte: KOH in water
R d ti
„ Redox reaction:
„ Anode:
„ Cathode:
−
+
+
→ e
aq
Zn
s
Zn 2
)
(
)
( 2
„ Cathode:
„ Voltage: 1.5V
)
(
2
)
(
)
(
2
)
(
2
)
(
2 3
2
3
2
2
4 aq
NH
l
O
H
s
O
Mn
e
s
MnO
aq
NH +
+
→
+
+ −
+
„ Voltage: 1.5V
Resource: Duracell
Further information: Energizer (How
battery works?)

13. Silver Oxide Cell
Silver Oxide Cell
„ Anode: amalgamated zinc
C th d il id
„ Cathode: silver oxide
„ Electrolyte: potassium
hydroxide
hydroxide.
„ Silver oxide cells are ideal for
„ Silver oxide cells are ideal for
miniature devices where
space is limited.
p
„ Voltage: 1.5 to 1.2 V
„ Uses: Watches

14. Silver Oxide Cell
Silver Oxide Cell

15. Some other batteries
„ Alkaline battery (Primary Type)
„ Improvement from Zinc-Carbon dry cell
„ Replace electrolyte with Manganese Dioxide (alkaline substance)
„ Replace electrolyte with Manganese Dioxide (alkaline substance)
„ Lithium-iodine battery (Primary Type)
„ Commonly use in watches, camera, etc
„ Low self-discharge rate (higher storage life time)
„ Lead-acid battery (Sec. Type)
„ Commonly use in car, motorcycle, produces 12V
„ Commonly use in car, motorcycle, produces 12V
„ Lithium-ion battery (Sec. Type)
„ Notebook computer, laptop, motherboard ROM battery
„ Produces range of 1.5 V to 3.6V, very light
„ SONY Lithium-Ion Technology

16. Specification / Main Concern
Specification / Main Concern
on Battery
„ Voltage
„ 1.5V, 3V, 9V, 12V,…
„ Size
„ AA, AAA, D, C, Li123, flat pack, …
„ Ampere-hours (Ah)
„ Normally measured in mAh (miliampere-hours)
„ Rechargeability
„ Rechargeable, non-rechargeable
„ Connectors (expandability)
Main sources:
Tower Hobbies,
Energizer

17. Voltage
„ Depends on how many unit cell in a pack
„ Normally, alkaline battery is 1.5 V per cell
1.0V x 6 units =
„ Some others (voltage per unit cell):
„ Lithium-iodine: 3V
„ Ni-Cd: 1.2V
1.0V x 6 units
6V
„ Ni Cd: 1.2V
„ Ni-MH: 1.2V
„ Lead-acid: 2V
Lithi i 3 6V
1 cell unit
(1.0V)
„ Lithium-ion: 3.6V
„ Connect them in series to vary the voltage, eg. flat pack,
lead-acid batteries. Information: Power Stream
„ WARNING: DON’T CONNECT DIFFERENT BATTERIES
WITH DIFFERENT CHEMICAL CONTENTS
2V x 6 units = 12V
Source: Motorradwerk Zschopau, Finland

18. Size
„ Main consideration to fit in battery room in
the appliances
„ Most common: AAA, AA, C, D (Cylindrical
cells), 9-V (Square cell)
„ Available some sizes, fitting race cars: flat
Available some sizes, fitting race cars: flat
battery
Flat batteries Sealed battery

19. Ampere-hours
„ Ampere-hour (Capacity)= current x hour
„ Equivalent to Coulomb (1 Ah = 3600 C)
„ Relate time and current (Battery life)
„ High current (high discharge rate), less consumable
hours
hours
„ Low current (low discharge rate), more consumable
hours
hours
„ Typically:
„ For RC cars: 1000, 1200, 2000, 2400, 3000 mAh
„ For RC cars: 1000, 1200, 2000, 2400, 3000 mAh
„ For heavy duty applications: can go up to 1000 Ah
„ Normally it is indicated on the battery
„ Normally it is indicated on the battery

20. Rechargeability
„ Why we prefer rechargeable batteries
„ Environmentally friendly
Reduce cost Æ don’t have to buy disposable batteries every
„ Reduce cost Æ don t have to buy disposable batteries every
time
„ Primary battery
y y
„ Non-rechargeable
„ Non-reversible chemical process
E l Z C Li I di Alk li b tt i
„ Example: Zn-C, Li-Iodine, Alkaline batteries
„ Secondary battery
„ Rechargeable
„ Rechargeable
„ Reversible chemical process
„ Example: Ni-Cd, Ni-MH, Lead-acid, Li-Ion batteries
p , , ,

21. Rechargeable Battery
„ Selection of chemical content needs to be very
careful
„ Selection of charger needs to match the specific
chemical content
chemical content
„ Primary batteries are not rechargeable, it may
explode or leak if recharged
explode or leak if recharged
„ Next few slides will go into a few popular
commercial rechargeable batteries

22. Nickel-Cadmium (Ni-Cd)
„ One of the common and popular
rechargeable battery especially in
rechargeable battery, especially in
codeless phone, RC race car
„ Available in different sizes:
cylindrical (AA, AAA, C, D), flat
battery pack
But:
„ But:
„ Cadmium is a toxic chemical - heavy
metal
„ Have Memory Effect (in next few slides)
„ Some information:
RC Battery Clinic
„ RC Battery Clinic
„ Panasonic Nikel Cadmium
Source: RC Battery Clinic

23. Nickel-Cadmium (Ni-Cd)
„ Commonly called Ni-Cd cell
& low maintenance
& stable discharge voltage
ll l b l
& excellent reliability
„ long operational life, It can be recharged up to 1000 times
„ Chemical contents:
„ Anode: Cadmium (Cd)
„ Cathode: Hydrated nickel oxide (NiOOH)
„ Electrolyte: Potassium Hydroxide (KOH)
lf ll
„ Half-cell reactions:
„ Anode:
„ Cathode: −
−
+
→
+ e
s
OH
Cd
aq
OH
s
Cd 2
)
(
)
(
)
(
2
)
( 2
„ This gives us 1.5V
q )
(
)
(
)
(
)
( 2
)
(
)
(
)
(
)
(
)
( 2
2 aq
OH
s
OH
Ni
e
l
O
H
s
NiOOH −
−
+
→
+
+

24. Advantages & Disadvantages of
Nicad Battery
„ Advantages:
„ Light weight (high energy density).
„ Rechargeable up to 1000 times.
„ Tolerate trickle charging.
l d h h
„ Low internal resistance, can produce higher current.
„ Disadvantages:
„ Cadmium is heavy and toxic metal (need extra careful
in handling and disposing).
Memory effect
Some concepts will be discussed in next
few slides
„ Memory effect.

25. Nickel-Metal Hydride (Ni-MH)
„ Motivation: One of the best cathode is hydrogen
(H). But, H is gaseous, how to use it in battery
d i ?
design?
„ In late 1960’s, scientists found some metal alloys
bl t t t i H (1000 ti f th
are capable to store atomic H (1000 times of the
alloys volume!). These metallic alloys called
hydrides Eg LiNi or ZrNi
hydrides. Eg. LiNi5 or ZrNi2.
„ So… development of this battery was based on
Nicad battery instead of using these metal
Nicad battery, instead of using these metal
hydride as cathode.
Source:
Source:
Extreme Tech

26. Nickel-Metal Hydride (Ni-MH)
Nickel Metal Hydride (Ni MH)
„ Chemical content:
„ Cathode: Metal Hydrides
„ Cathode: Metal Hydrides
„ Anode: Nickel
„ Electrolyte: Potassium hydroxide
„ Electrolyte: Potassium hydroxide
(KOH)
„ Half equations:
q
„ Charging:
„ Anode:
−
−
+
→
+
+ OH
H
Alloy
e
O
H
Alloy ]
[
2
„ Cathode:
„ Discharging
Anode:
−
−
+
+
→
+ e
O
H
NiOOH
OH
OH
Ni 2
2
)
(
−
−
O
H
All
OH
H
All ]
[
Source:
Extreme Tech
„ Anode:
„ Cathode:
+
+
→
+ e
O
H
Alloy
OH
H
Alloy 2
]
[
−
−
+
→
+
+ OH
OH
Ni
e
O
H
NiOOH 2
2 )
(

27. Advantages & Disadvantages of
Ni-MH Battery
„ Advantages:
„ No toxic materials (like Nicad, Cd is a heavy metal)
„ No memory effect (next few slides)
„ H is the best cathode
d 0% h h h d
„ Energy density is 50% higher than Nicad. (Concept of “Energy
density” will be presented in the next few slides)
„ 500 to 1000 recharges
g
„ Disadvantages:
„ Higher self-discharge rate. (less 5% per day)
g g ( p y)
„ Drive less current compared to Nicad

28. The Memory Effect
„ Phenomenon of when rechargeable battery is frequently
recharged before it is finished discharged, then the
battery will require to be charged more sooner than
battery will require to be charged more sooner than
before.
„ Reason: the battery “memorized” the time to stop
y p
discharging.
„ For instance: if you normally recharge a 1.5V battery
when it reaches 1 2V then it will stop producing power at
when it reaches 1.2V, then it will stop producing power at
that voltage level. (The battery assumed you don’t need
power when below 1.2V).
p )
„ This normally happens on Ni-Cd battery, but not Ni-MH.

29. The Memory Effect
„ Scientific explanation:
„ Chemically recharging Nicads before they are fully discharged often
results in the formation of cadmium crystals on the anodes of the cell
Source: Extreme Tech
y
„ The crystals act like a chemical memory system, marking a second
discharge state for the cell
„ When the cell gets discharged to this secondary discharge state, its
g g y g ,
output abruptly falls despite further capacity being available within the cell
„ In subsequent cycles, the cell remembers this second discharge level,
which further aggravate the situation by reinforcing the memory of the
d di h t t
second discharge state
„ To prevent – operate them between extremes (operate
the battery through its complete cycles)
the battery through its complete cycles)
„ How? We need “discharger” to discharge the energy remained in
the battery

30. Lead Acid Battery
Lead Acid Battery
T i l
Terminal
Post
Terminal
Post
Plastic
Case
Post

31. Sealed Battery
„ The battery has a square case to prevent liquid (acid)
leakage
leakage
„ Use in Lead-Acid battery (Acid is sulfuric acid, H2SO4)
„ Half Equations:
„ Half Equations:
„ Anode:
„ Cathode:
−
+
−
+
+
→
+ e
aq
H
s
PbSO
aq
HSO
s
Pb 2
)
(
)
(
)
(
)
( 4
4
O
H
s
PbSO
HSO
H
s
PbO 2
4
4
2 2
)
(
3
)
( +
→
+
+
−
+
Source: Great Hobbies

32. Valve Regulated Lead-Acid
(VRLA) Battery
„ Latest technology: Valve-Regulated Lead-Acid (VRLA)
battery
„ This technology allows the control of the amount of
„ This technology allows the control of the amount of
electrolyte required and gas released to the
atmosphere in the battery
Advantages:
„ Advantages:
„ Longer battery life
„ No need to add water frequently
No need to add water frequently
„ Less maintenance required
„ Some related links:
„ Varta
„ SEC – VRLA Battery
Head Torches Tiger Tools Ltd
„ Head Torches, Tiger Tools Ltd.

33. Energy Density
„ A measure of how much energy can be stored in a
specific mass. Unit: Ampere-Hour per Kilogram
spec c ass U t pe e ou pe og a
(Ah/kg).
„ Why important? Because we demand high energy
density battery (with small battery weight, we have
more energy! And drive more power, with longer
battery life!).
„ Interesting research: Lithium (Li) related battery
technology.

34. Lithium-Ion Battery
„ Lithium is the most chemically reactive metal. It is
at the highest in Electrochemical Series
g
„ Lithium is also one of the lightest metal
„ Today’s most compact energy storage (High
„ Today s most compact energy storage (High
Energy Density), about 3860 Ah/kg.
(Zinc: 820 Ah/kg 260 Ah/kg)
(Zinc: 820 Ah/kg, 260 Ah/kg).
„ Commonly used in notebook / laptop computers

35. Lithium-Ion Battery
„ Depending on cathode, it can produce from 1.5 V
to 3.6 V
„ Problem: Since it is very reactive, it can easily
react with water and air. We need to look for
t d it ti it
someway to reduce its reactivity
„ Method:
„ Design it under ionic state (that’s why it’s called Li-Ion)
„ Let other active material absorb its ionic state, instead
of plated at the battery’s electrode
of plated at the battery s electrode
„ Electrodes design – Interesting challenge

36. Lithium-Ion Battery
„ Electrode Design:
„ Cathode: Lithium Cobalt Dioxide
„ Anode: Carbon (Look below)
„ Electrolyte: Some lithium salt in aqueous solution
„ Anode design technology:
„ Used graphite (Carbon), or some polymers. Latest
device like iPod is using Lithium Polymer battery
device like iPod is using Lithium Polymer battery
„ SONY Lithium-Ion Technology
„ Ultralife Polymer Cell
„ Reading: Extreme Tech, Ultralife

37. Advantage & Disadvantage of Li-
Ion Battery
„ Advantages:
„ High energy density
„ Very light
„ High Voltage
„ Disadvantages:
„ High internal resistance (can’t produce high current)
„ Liquid electrolyte (need careful container design)
„ Can power just about to drive notebook computers

38. Lithium Ion Battery
& High reactivity of lithium metal
& Dendritic formation of lithium during the charging
process
& poor cycle performance
& longer charging time
& poor safety characteristics
How to resolve the problem???

39. When to use which battery
When to use which battery
„ Application / Appliances Determination:

40. Get in touch with battery
technology
„ Varta Battery
„ Ultralife Battery
„ Ultralife Battery
„ PowerStream Technology
Energizer Battery
„ Energizer Battery
„ Duracell Battery
„ Extreme Tech
„ Valence Technology, Inc
Valence Technology, Inc
„ Green Batteries

41. Charger
Source: Astron Smart Charger
„ Device to recharge discharged-rechargeable
batteries
Source: Astron Smart Charger
„ Cell chemistry is very sensitive to the electricity
applied to
„ Too low – not charging the battery, but the battery
providing power to the charger
Too high some undesirable reaction might take place
„ Too high – some undesirable reaction might take place
and destroy the battery, may even explode!
„ Main concern:
„ Main concern:
„ How to charge? (Constant current / voltage)
„ When to turn off? (Voltage / temperature dependence)
„ When to turn off? (Voltage / temperature dependence)
Source: Extreme Tech

42. Constant Voltage
„ Simplest way:
„ Produce a specific voltage level to allow current deliver
t th b tt
to the battery
„ As the battery is charged, voltage is increased
So the potential difference between the charger
„ So, the potential difference between the charger
become lesser, less current delivers to the battery
„ Component required:
„ Component required:
„ Transformer: reduce line level to the required voltage
by the battery
„ Rectifier: convert AC to DC
„ Advantage – easier to know when to stop charging
„ Applications – Lead-Acid, Li-Ion
Source: Extreme Tech

43. Constant Current
„ Apply constant current but vary voltage
level
„ Constant current means constant charge
Since voltage level increased when
„ Since voltage level increased when
charged, the charger turn off when the cell
reached a specific high voltage
reached a specific high voltage
„ Applications – Nicad, Ni-MH

44. Turning off
„ So… when to turn off the charger?
„ What is the “specific voltage” to turn off?
„ What is the specific voltage to turn off?
„ How long do I need to charge my battery?

45. Turning off
„ Methods:
„ Voltage sensor – cut-off voltage (VCO)
„ Voltage sensor cut off voltage (VCO)
„ Temperature sensor – cut-off temperature
(TCO)
(TCO)
„ Combined both – Voltage & Temperature cut-
ff (VTCO)
off (VTCO)

46. Voltage Cut Off
Constant Current
Voltage Cut-Off
{C=270 mAHrs}
„ Voltage sensing at the
“slope” of the voltage
slope of the voltage
change.
„ Turn off when voltage
h i l
change is large.
„ Easy, but some batteries
can’t apply this technique,
can t apply this technique,
eg. Nicad has very linear
discharge curve, hard to
determine the cut-off
determine the cut off
voltage

47. Temperature Cut-Off
Temperature Cut Off
„ Most advanced charger use
this technique
this technique
„ Monitor the temperature of
the battery while charging
y g g
„ Batteries get hot when
charged
ff b ki d f l
„ Turn off by some kind of relay
control
„ This kind of charger is safer
„ This kind of charger is safer,
typically Nicad and Ni-MH
uses this charger, because
their temperature curve is
their temperature curve is
easier to monitor

48. Voltage & Temperature Cut-Off
„ More sophisticated
„ Can switch from high
current charging to
lower depending on
both voltage and
temperature change

49. How much current?
„ Another issue – supply how much current?
„ More common terms – trickle charger or
„ More common terms – trickle charger or
fast/rapid charger
„ Trickle charger: low current
„ Fast/rapid charger: high current
„ Fast/rapid charger: high current

50. Trickle Charger
„ Supply very low current – just about greater than
its self-discharge rate (about 1/20 to 1/30 of the
g (
battery self-discharge rate)
„ Advantage – avoid overcharged
Advantage avoid overcharged
„ Disadvantage – very slow, normally overnight
However some batteries can’t tolerate trickle
„ However, some batteries can’t tolerate trickle
charge, eg. Nicad batteries

51. Fast / Rapid Charger
„ Supply high current to fast charge battery
„ Need extra careful when using this charger,
„ Need extra careful when using this charger,
because it may overcharge the battery
Older version: need to turn off by yourself
„ Older version: need to turn off by yourself,
rough calculation of required hours needed.

52. S t Ch
Smart Chargers
„ This leads to the design of smart chargers –
„ Smart chargers can switch from fast charge to trickle charge
g g g
„ The battery is initially charged at high current until it reaches
certain voltage level
„ It then switches to trickle charge (remember, just about its self-
g ( , j
discharged rate) to maintain it’s the particular voltage level
„ Trickle charge acts as a tool to store the battery
„ More advanced charger can even shows which battery are you
g y y
charging
„ Normally combined Nicad and Ni-MH (because their charging
characteristics are similar)
„ Some charger specifies only some specific batteries can be
charged. Read the details carefully before charging!
„ This is one kind of mechatronics design – sensor, microcontroller,
t t
actuator

53. Determination of Suitable
Charger
„ Highly recommended smart chargers
„ Caution – read carefully the battery details:
„ Most manufacturers provide the charging and
Most manufacturers provide the charging and
discharging curves (V vs. time with const. T or
T vs. time with const. Current)
)
„ How long to charge? Use Battery Charge -
Time Calculator (by Green Batteries)
Time Calculator (by Green Batteries)

54. Electromotive Force (emf)
„ Energy is required to move electron from anode to
cathode
Th i d it h i ll d
„ The energy required per unit charge is called
Electromotive Force (emf)
„ Unit: 1 V (Volt) = 1 J/C (Joule per Coulomb)
„ Unit: 1 V (Volt) = 1 J/C (Joule per Coulomb)
„ This quantifies the “energy available” in a voltaic cell
„ Note: the term “emf” is the same as the emf generated
„ Note: the term emf is the same as the emf generated
by a conductor in a magnetic field (Faraday’s Law)
„ With the availability of this energy, battery is “potential”
y gy, y p
to power electrical appliances

55. Determining Potential (Voltage)
of Battery
„ Emf of each half-reaction at the voltaic cell can be found
in a tabulated form (Standard Electrode Potentials in
Aqueous Solution at 25°C)
Aqueous Solution at 25°C)
„ We have:
„ Reduced species Æ oxidized species + n e- (Oxidation / Anode)
„ Reduced species Æ oxidized species + n e (Oxidation / Anode)
„ Oxidized species + n e- Æ reduced species (Reduction / Cathode)
„ Cell emf
„ Ecell = oxidation potential + reduction potential
„ Ecell = Ecathode – Eanode (Since the voltage of cathode must be
positive, and the potential of anode is negative)
p , p g )

56. Voltage Level in Battery
„ Why is battery “consumed”? (Voltage drop)
„ Dependence of emf with concentration Æ related by
N t E ti
Nernst Equation
0592
0
where Q is equilibrium constant (KP or Kc), n is the
number of electrons transferred in a reaction
Q
n
E o
cell log
0592
.
0
=
number of electrons transferred in a reaction
„ Since Q is dropping throughout the chemical process,
until it becomes equilibrium (stop reacting), the emf is
d l
dropping also
„ How to calculate Q? See: Link from Dept. of Chem., Purdue Univ

57. Lithium Ion Battery
y
& Lithium reacts with graphite to form
lithium graphite intercalation
lithium graphite intercalation
compounds ⇒ LiC6
& Graphite as anode
ap a a od
& Lithium cobaltite (LiCoO2) as
cathode
& Reversibly charged and
discharged
& Overall cell reaction:
LiCoO2 + Lia-dxC Li1-dxCoO2
+ LiaC

58. Lithium Ion Battery
Lithium Ion Battery

59. Lithium Ion Battery
& High dielectric constant
electrolyte
electrolyte
& high viscosity ⇒ low ionic
conductivity
conductivity
& Separator
i fil
& microporous film
& prevent direct contact
between 2 electrodes
between 2 electrodes
& prevent thermal runaway

60. Lithium Ion Battery
Lithium Ion Battery
& Improvements: & Precaution:
& Use less expensive
material such as LiNiO2
d LiM O
& control the top-of charge
voltage carefully
if f il t d
and LiMn2O4
& Inc. the Li doping
capability of carbon by
& if failure to do so
& ⇒ decomposition of the
positive electrode materials
capability of carbon by
the addition of
phosphorous or heat
positive electrode materials
& ⇒ oxygen gas and Co3O4 may
be produced
phosphorous or heat
treatment of carbon with
boron
be produced
& use specially designed charger