Batteries 2. Research and Development in Non-Mechanical Electrical Power Sources

532 Pages·1965·10.414 MB·English

by  D. H. Collins (Eds.)

Batteries 2
Research and Development in
Non-Mechanical Electrical Power Sources
Proceedings of the 4th International Symposium
held at Brighton, September 1964
Sponsored by the Inter-Departmental Committee
on Batteries
Edited by
D. H. COLLINS
SYMPOSIUM PUBLICATIONS DIVISION
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Copyright © 1965
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First edition 1965
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SYMPOSIUM COMMITTEE
Representing the Inter-Departmental Committee on Batteries
D. H. COLLINS Admiralty Engineering Laboratory {Chairman)
L. H. CATT Post Office Engineering Dept.
Dr. R. K. PACKER Admiralty Underwater Weapons Establishment
R. THOMAS Signals Research and Development Establishment
F. C. WELLS, M.B.E. Ministry of Aviation Elec 1
F. J. L. COPPING {Secretary)
Representing Industry
F. AUFENAST The Ever Ready Co. (G.B.) Ltd.
Dr. M. BARAK Chloride Technical Services Ltd.
M. J. H. LEMMON The McMurdo Instrument Co. Ltd.
G. A. S. PALMER G. A. Stanley Palmer Ltd.
L. R. PROUT Oldham and Sons
Dr. P. REASBEGK Joseph Lucas (Electrical) Ltd.
v
FOREWORD
THE first four International Symposia on Batteries have been sponsored by
a British government committee, the Inter-Departmental Committee on
Batteries. Future Symposia will be sponsored by the Joint Services
Electrical Power Sources Committee which has taken over the activities
of the I-D.C.B. with wider terms of reference to include all types of power
sources on which reports have been presented at the Symposia.
The Symposia are organized by a joint working committee on which the
government and British industry are equally represented. Industry pro-
vided the initial financial backing which is a necessary prerequisite to such
regular events, and also provides many of the services which are essential to
the smooth running of the Symposia. As a result of this help it has been
possible to keep registration fees at a low level, but it is the policy of the
working committee that the Symposia shall eventually become self-
supporting.
Although the primary interest of the Symposia is in batteries, every
encouragement has been given to the inclusion of papers on other power
sources—except rotating machinery—which may compete, or work in
conjunction, with batteries.
There are no restrictions on attendance at the Symposia and a high
proportion of both the delegates and the papers presented come from
overseas countries. Many of the papers come, naturally, from industry and
from government and other establishments where work on power sources is
in progress, but a feature of the Symposia is that prominence is also given to
papers from universities and from users. This is of particular value as it
brings to the attention of a wide and varied audience not only the little-
known background work which is associated with power sources, but also
the problems, and sometimes their solution, with which the user is faced in
the selection and operation of a power source to meet his particular
requirement.
Since the Symposia are the only international meetings covering this
particular field, apart from those held in North America, they afford a
rare opportunity for the workers and users to discuss their subject. Every
effort is, therefore, made to encourage discussion on the papers. To further
this end pre-prints of the papers are issued to the delegates in advance of the
Symposia so that the time for their presentation can be restricted and the
maximum time allowed for discussion. These discussions are recorded and,
in an edited form, included at the end of each paper in these Proceedings.
The Symposia will continue to be held at two-yearly intervals and the
next will be held at Brighton on 20th to 22nd September 1966.
vii
OPENING ADDRESS
SIR ALBERT MUMFORD, K.B.E., B.SC.(ENG.), F.Q,.M.C., M.I.E.E.
Engineer-in-Chief, Post Office, President Institution of Electrical Engineers 1963/64
{Presented by D. A. Barron)
Your invitation last November to open this Symposium gave me a unique
opportunity of accepting as Engineer-in-Chief of the British Post Office, and
taking part in your proceedings as the President of the Institution of
Electrical Engineers, the timing of your Conference just coinciding with
my last few days as President. I, therefore, readily accepted your invitation,
only to find when the time arrived that my duties as President have in the
event made it impossible for me to present this Address in person as
Engineer-in-Chief, since I am now making, with my wife, a Presidential
visit on behalf of the Institution of Civil, of Mechanical and of Electrical
Engineers to Toronto, New York, the West Indies and South America.
Having left the country on the 21st of August I am not due to arrive back
until the 30th of September, just too late, I regret, for my wife and I to take
any active personal part in your Conference or even its functions. When I
accepted your invitation some nine months ago I had no idea that this
unique opportunity was in the event going to face me with this clash of
interests. I apologize sincerely and in doing so would like to take this
public opportunity of thanking my Deputy Engineer-in-Chief, Mr. D. A.
Barron, for so readily agreeing to present my Address for me.
Storage of electrical energy is a subject of considerable importance to
electrical engineers. The titles of the papers in your programme clearly
show the amount of active research and development that is taking place,
not only in the conventional battery field, but also on various other newer
sources of power. It is not surprising to learn, therefore, that, as fore-
shadowed by Sir Solly Zuckerman when opening the last Symposium, you
are now adopting the more appropriate title of Joint Services Electrical
Power Sources Committee.
Progress in battery design is unobtrusive, but when one compares
batteries of today with those of the past, the improvements that have been
made are soon evident. I remember during my early days when we were
given a guaranteed battery life of two years for traction type lead-acid cells
worked on a regular cycle, it was considered the hallmark of a good battery.
Improvements, however, resulted in this guarantee being increased to three
xiii
xiv SIR ALBERT MUMFORD
years, and further development enabled the manufacturers in 1949 to
guarantee a four-year life. As the actual average life of such batteries is now
probably nearer six years, dare we hope for a five-year guarantee in the
near future? It is strange, however, that progress is not always welcomed,
as one of our fork-lift truck manufacturers found when he had to provide
several hundredweights of additional ballast cast iron on being offered
improved batteries of the same voltage and capacity, but 25 per cent lighter
than his standard type.
The applications and duty cycles of batteries vary enormously, and whilst
those for the fighting services often require high output with small size,
weight and life expectancy, batteries for life-boats and pilot's life jackets are
inactive for very long periods and are then used under most unfavourable
emergency conditions when extreme reliability is essential. In the tele-
communications field, in which I have spent most of my life, the Post Office
has had a long experience of stationary batteries, our main requirements
being reliability, long life and the ability to work for long periods without
attention. The early telegraph systems used Daniell and Leclanche cells,
and the Post Office still spends about £100,000 every year on dry Leclanche
cells. Secondary cells were first used on telegraphs in 1883, and in a tele-
phone exchange in 1893 in Liverpool—now more famous for Beatles than
batteries. Since those years, the number and capacity of secondary cells
installed have increased to such an extent that they are now costing us
nearly half a million pounds each year. The batteries in some of the large
telephone exchanges comprise cells of 15,000 A-hr capacity, each weighing
more than 3 tons, whilst the Faraday building 24 V, 131,000 A-hr
installation consisting of 32 parallel rows each of 4100 A-hr capacity was
probably one of the largest capacity batteries in the world. The lives of such
large batteries depend very much on the method of working, and whilst the
Faraday battery gave a life of 10 years before we had to make rearrange-
ments to the supply, some of our batteries have had useful lives of up to 25
years. Battery-driven vehicles are also used in the postal service for trans-
porting mail to and from sorting offices, and for parcel delivery, and it is
interesting to recall that the Post Office was one of the first commercial users
of electric battery transport in this country when it operated a postal service
between Waterloo Station and the London District Post Offices as long ago
as 1902. It has been our practice to design telecommunications transmission
equipment to operate from the a.c. mains supply, with power packs on the
racks to provide the various voltages required. The standby power supply
during emergency conditions has been provided by diesel engines or con-
tinuously rotating machines. Experience has shown us that a great deal of
electrical circuitry and automatic switchgear are needed to start, stop,
provide the necessary voltage control and safeguards for such prime movers
and that their reliability for important telecommunications circuits has not
Opening Address xv
always been as good as we require. Consequently, we are now having to
make a reappraisal of these standby facilities to ascertain whether it would
not be better for this transmission equipment to be designed for d.c. opera-
tion from batteries, thereby using the battery as a standby as we do in tele-
phone exchanges. The development of the transistor as an amplifier also
increases the tendency for future transmission equipment to be operated
from a d.c. source. The transistor is also used to perform switching opera-
tions in the development of the electronic telephone exchange and, being
operated by voltage changes, it is sensitive to voltage surges in the supply
system. Hence your Paper No. 16 dealing with the transient voltage which
occurs immediately the lead-acid secondary cell is connected to its load is
now of considerable interest to telecommunications engineers. We would
welcome some authoritative data on the characteristics of these transients,
and would like to know whether the manufacturers can see any possibility of
reducing their values by improvement in battery design.
The lead-acid cell, which was invented more than a century ago, is still
the most widely used method of storing electrical energy, and it is not sur-
prising that two-thirds of your papers are on this and other conventional
types of cell. It is nevertheless interesting to look at the future possibilities of
developing some of the more recently discovered power sources now coming
within the Committee's widened terms of reference. Those delegates who
are doing research and development work on fuel cells are clearly aware of
the potential market for a primary cell which can be continuously fed by a
conventional fuel; and I note that a quarter of your papers are devoted to
this subject. The hydrogen-oxygen cell has been successfully developed to
give outputs of several kilowatts with efficiencies of 80 per cent, but at
present it is very bulky and expensive, as such efficiencies can only be
obtained by using almost pure hydrogen. Many other fuels are being
employed, but the main problems still to be solved appear to be the selection
of suitable materials to withstand the high temperatures and pressures and
the efficient use of readily available fuels that can be handled and stored with
safety. Several papers deal with solar cells which, when used for charging
storage batteries, have given promising results in applications requiring small
intermittent powers. Their most spectacular use has probably been in pro-
viding power to satellites, but many successful terrestrial applications have
also been demonstrated. They have been used for operating fog horns,
warning signals on navigation buoys, and a most interesting application was
the five-year unattended battery charging by solar cells in supplying power
to a v.h.f. radio telephone repeater, described in Paper No. 27 at the last
Symposium. The efficiency of silicon cells has increased from 10 to 15 per
cent during the past few years, and with further improvements in materials
and manufacturing techniques, the ideal efficiency of 22 per cent and voltage
of 0-5 V may soon be achieved. Large solar cells are usually made by
xvi SIR ALBERT MUM FORD
assembling together many of these small cells, but new manufacturing
processes are now being evolved to develop single large area cells which will
be more efficient, lighter and stronger. I was rather surprised when I did
not find a paper in the Symposium on thermoelectric generators, as these
are now available in this country in sizes up to 50 W using propane gas as the
heat source. They have supplied power for many applications in isolated
situations where maintenance is not readily available, and we are now
considering their use on the radio telephone circuits between the remote
Scottish islands and the mainland. Other power sources, which no doubt
will be subjects for your next Symposium, are thermionic generators using
the well-known thermionic valve principle, and magnetohydrodynamic
generation from ionized moving gases, which is now a major commercial
research effort. I see that there is already in this programme one paper on
nuclear energy units. These sources have all been developed in small sizes
in the Laboratory for special applications and perhaps to us now, the picture
of a nuclear power box with two terminals which will provide electrical
power for many years is not quite as fantastic as a television picture from a
satellite appeared to us in our youth.
This is an international meeting and both Sir Albert and I have taken
part in many such meetings during our careers. What we have both appre-
ciated as engineers is how freely information and ideas are exchanged, and
the many friends we have made, in such Conferences. Can I, therefore,
thank you for allowing me to present this Address on behalf of the Engineer-
in-Chief and to wish you a Symposium full of interest and of real value to
you all?
1
THE USE OF DISPERSION-STRENGTHENED
LEAD AS POSITIVE GRIDS IN THE LEAD-ACID
BATTERY
N. E. BAGSHAW and T. A. HUGHES
Chloride Technical Services Limited, Swinton, Manchester
ABSTRACT
The metallurgical properties of a positive grid alloy are discussed and the properties
of dispersion-strengthened lead are given. The mechanical properties and creep
resistance of some samples of dispersion-strengthened lead are shown to be good whilst
their corrosion resistance and stress-corrosion life under anodic conditions is satisfactory.
Motor cycle cells with positive grids of dispersion-strengthened lead gave a satisfactory
performance on overcharge with good maintenance of top-of-charge voltage. Similar
cells gave premature failure on cycling because of positive active material shedding.
Further investigations are required on methods of fabricating grids from dispersion-
strengthened lead and on methods of joining the material.
INTRODUCTION
A large number of batteries finally fail in service because of disintegration
of the positive plate. In the search for new grid alloys, it is therefore important
to know the properties which are necessary for a positive grid to function
satisfactorily in service. These properties are as follows. Firstly, a grid
should have sufficient mechanical strength to withstand the various manu-
facturing processes without breaking or distorting. The second important
property of a positive grid is its creep resistance. It is well known that a
positive plate will " grow " during service because of the stresses which are
exerted on the grid from various sources. It has been found that grids which
are highly resistant to growth can be made from alloys with high creep
resistance. The third factor to consider is the corrosion resistance of a grid.
This is obviously important in order to obtain a long life from a battery. In
the actual operation of a battery, however, the positive grid is corroded and
subjected to various stresses at the same time. It is therefore important to
know the corrosion resistance of a grid alloy when a stress is superimposed.
Thus, in considering a new alloy for a positive grid the mechanical strength,
the creep resistance and the corrosion and stress corrosion resistance under
anodic conditions should all be tested.
Lead-antimony alloys containing 6-12 per cent antimony with small
amounts of arsenic and other alloying additions have been used for many
1
B
2 N. E. BAGSHAW AND T. A. HUGHES
years in the battery industry. The metallurgical properties of these alloys
are satisfactory. Their advantages are good mechanical properties, high
creep resistance, reasonable corrosion resistance and excellent castability.
Cells assembled using lead-antimony positive grids give a fairly good life.
However, it is well known that, during service, antimony is released into the
electrolyte and, on charging, is deposited with the spongy lead on the negative
plate. Here it causes a reduction in the hydrogen overvoltage, and hydrogen
evolution and loss of charge can result.
The electrochemical characteristics associated with antimony in a battery
are undesirable in some applications where low open circuit losses are
necessary or where hydrogen evolution cannot be tolerated. For this reason,
investigations have been carried out for many years on low-antimonial and
non-antimonial alloys for positive grids. Lander(1) showed that lead alloys
containing 0-05-0-15 per cent calcium had reasonable mechanical strength
and corrosion resistance and an alloy containing 0-065-0-085 per cent
calcium has been used for some years in the U.S.A. A lead-3 per cent tin-
0-05 per cent barium alloy was also proposed for positive grids by Parr,
Muscott and Crocker.(2> 3) More recently, dispersion-strengthened lead has
become available and the possibility of using this material as a positive grid
is being investigated in these laboratories.
The principle of strengthening a metal by a dispersed phase has been
known for many years. Sintered aluminium powder (SAP), in which
aluminium is strengthened by aluminium oxide, was investigated many
years ago, but the technique was not applied to lead until 1962 when Roberts,
Ratcliffe and Hughes(4) showed that lead could be strengthened in this way.
Lenel(5) has also investigated lead strengthened with dispersions of copper
and aluminium.
The present paper reports the work carried out on the use of dispersion-
strengthened lead as positive grids in batteries. The lead, strengthened by
dispersions of lead oxide, was obtained from two sources and was in the form
of rolled sheet.
LABORATORY EVALUATION
Experimental Procedure
Tensile and hardness tests were carried out on the Hounsfield Tensometer.
In the tensile tests, a shaped specimen 0-5 in. wide with a 2 in. gauge
length was cut from the sheet. A 5 mm diameter ball was used in the
hardness test with a 25 kg load for 15 sec. Tests were carried out in duplicate.
Creep tests were carried out on a shaped specimen 0-5 in. wide with a
4-5 in. gauge length cut from the sheet using a constant load with an initial
stress of 2000 lb/in2. The percentage strain was measured by a travelling
microscope.
Rapid anodic corrosion tests were carried out in 1 -250 s.g. sulphuric