AU653616B2

AU653616B2 - Equipment casing incorporating energy storage device

Info

Publication number: AU653616B2
Application number: AU20790/92A
Authority: AU
Inventors: Jean-Pierre Dumas; Alain Le Mehaute; Pierre Lerner
Original assignee: Alcatel NV
Current assignee: Alcatel Lucent NV
Priority date: 1991-08-07
Filing date: 1992-08-03
Publication date: 1994-10-06
Anticipated expiration: 2012-08-03
Also published as: AU2079092A; FR2680270A1; NZ243856A

Description

11100/01l 28/5/91 Regulation '1.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDAR(D PATENT Invention TiLb: "EQUIPMENT CASING INCORPORATING ENERGY STORAGE DEVICE" The following statement. is a full deceription of the invention, including Llic bost method of pcr-forming it known to us:-

S

This invention relates to an electronic equipment casing containing an electrical energy storage device. The casing furthermore provides electromagnetic shielding for the equipment.

In numerous electronic equipments and particularly in portable electronic equipment such as radiotelephones, the twofold problem arises of electrical power supply and electromagnetic shielding. In other respects it is desirable that these equipments be neither heavy nor voluminous and that the masses in the equipment are more or less uniformly distributed, and finally the cost being as low as possible.

Portable equipment, in particular, must be self-contained and consequently its power supply is generally provided by at least an electrochemical generator of the battery or accumulator type. Standard electrochemical generators are heavy, awkwardly shaped and dense. The electromagnetic shielding which must protect the circuits and components of the equipment from external electromagnetic influences is, for its part, generally obtained by combining screening of the equipment casing, in the form of a metallic or metallised sheet, which entails cost and possibly additional weight.

An object of the present invention is to resolve the problems of electrical power supply and electromagnetic screening in electronic equipment, in particular portable electronic equipment, by satisfying better than in the prior art and at a moderate cost, the requirements related to weight, volume and mass distribution.

20 According to the invention there is provided an electronic equipment casing of which at least a part of the wall surface comprises a laminated material composed of sheets including electrodes and an electrolyte separating the electrodes, the material constituting an electrical energy storage device used for the equipment's electrical power supply, moreover at icast one of the electrodes acting as an electromagnetic screen.

Thus the laminated material integrated into the casing serves at the same time both as an electrical energy storage device and as an electromagnetic screen, which allows the achievement of the previously mentioned objectives of uniform mass distribution and electromagnetic screening. The laminated material need only extend 30 over the major part of the casing, for example at least on all of the back of the casing.

Furthermore, the integration of the electrical generator and the casing in a single component again leads to a saving in weight.

Preferably, the electrode acting as an electromagnetic shield extends substantially over the entire surface of the casing.

Preferably, the said electrode acting as an electromagnetic shield is the outer one of the electrodes in the casing material.

Preferably, said laminated material is formable and extends substantially over the entire surface of the casing.

Preferably, lithium is used in at least one of the electrodes of the casing material.

Preferably, the electrolyte is a solid material composed of a polymer mixed with a salt and cross-linked by irradiation. In particular, polyoxyethylenes, in which salts such as LiAsF6, LiC104, LiCF3S03 and LiTFSI have been dissolved, can be used.

Preferably, one of the electrode-forming sheets is composed of a composite based on a polymer and on a c.ompound chosen from the group NiS2, NiPS3, FcPS3, V6012, V205, Mn02, (Bi203,Pb0), NiO(OH), Pb02, Co304, and LiCo02.

Preferably, the wall is comprised of a sandwich of hard plastic surrounding a laminated material as defined above.

In order that the invention may be readily carried into effect, an embodiment thereof will now be described in relation to the accompanying drawing, in which: Figure 1 is a representation of the casing of the invention; Figure 2 is a representation of the basic structure of the laminated material included in the casing of the invention; Figure 3 shows curves illustrating results of measurements related to the 20 electromagnetic shielding properties of the casing material of the invention.

i Figure 1 represents a portable electronic equipment casing 1, such as a radiotelephone. The casing comprises a cover 2 formed in the main by a frontal plate 3 equipped with an edge 4. The cover 2 is connected to the body of the casing formed for the main part by a back 6 and side walls 7. The connection comprises a 25 flexible hinge 8 which contains electrical conductors 9 covered with insulating material. The cover is fitted by its edge 4 to the side walls 7, to which it is fixed by means not shown, such as current technology latches, enclosing a volume containing, as well as the hinge 8, the electronic equipment of the device. For the purposes of use of the equipment, the cover 2 includes various openings, such as one opening 10 provided o30 for an indicator, or openings such as 11, each one corresponding a key of a keyboard represented at 12.

Furthermore, an opening 12' corresponds to an access hole for the aerial. By use of a standard technique, such a casing could be basically made by meK:ling from plastic or a plastic-based composite.

According to the invention, at least a part of the wall of the casing comprises a laminated material containing sheets having electrodes id an electrolyte separating the electrodes, the material constituting an electrical energy storage device used for the power supply of the equipment, at least one of the electrodes acting as an electromagnetic shield.

For example, the part of the wall of the casing in question is that which is demarcated by 13 and corresponds substantially to the complete surface of the back of the casing. But, preferably, the said material covers not only at least the back of the casing, but also the side walls, as far as the limit 14. The material can also cover to great advantage all or part of the cover, as illustrated in 15, the connections such as 9 provided in the hinge 8 providing the necessary electrical interconnections.

Figure 2 is a representation of the basic structure 20 of the laminated material included in the casing of the invention. The basic structure 20, which will be called "layer", with a total thickness of 300um, comprises 4 superimposed sheets whose relative thicknesses are contiguous; a sheet constituting one positive electrode 21, a sheet of solid electrolyte 22, a negative electrode sheet 23 and a conductor sheet 24.

This latter sheet is made from a good electrical conducting metal, such as silver or copper. Its role is to distribute or redistribute the current at the negative electrode, while compensating for some lack of electrical conductivity of the material of which VO 20 this electrode is made. The composition of three other sheets which constitute an electrochemical generator will be discussed later.

Generally speaking, sheets 21, 22, and 23 constitute a generator producing a voltage around 1.2V. A voltage of about 5V will therefore be obtained by stacking four layers in four sheets, such as in Figure 2, to form an assembly with a thickness 25 of 1.2 mm. At this thickness, the amount of electricity available will depend essentially on the surface area. It can be increased by superimposing several assemblies which will be connected in parallel. Higher voltages will be obtained by playing with the number of layers of assemblies and the connection of the assemblies in series or parallel. Agreed, the connections between assemblies and the generator output con- 0 nections will have to be worked out. This will be done in accordance with the usual techniques in this field.

A material comprising an assembly of several layers, each one conforming to that represented in Figure 2, is thus a flat body which can be cut up to have any shape, for example that demarcated by 13 or 15 in Figure 1. In addition, with the choice of deformable materials to make up the sheets, the material can be formed so as to fit the shape demarcated by 14.

The casing of Figure 1 will be obtained, from the material which has just been specified, by coating the material, for example by duplicate moulding, on a suitable plastic selected from those which are usually adoptrd for this application, such as PVC or ABS, thus producing a sandwich of hard plastic around a laminated material as defined above.

The electrodes of the electrochemical generator in Figure 2 act as an electrolmagnetic shield. This effect, which will be seen further into the future, is more or less effective according to the composition of the layer and its location in the material. It is preferable that the electrode acting as the electrolmagnetic shield be all of the said material closest to the external surface of the casing. It is also preferable that this electrode substantially covers all the surface area of the casing. In a case where the electrochemical generator would finish at the limits shown at 13 in Figure 1, the electrode acting as shielding would extend to great advantage, for its part, to what is demarcated at 14 and 15, with interconnection at 9.

In conformity with the prior art, the cutting of the different sheets, according to the shapes just considered, will of course be accompanied by every 20 measure such as additional insulation confined to the places to be protected, with the aim of avoiding any short-circuit between electrodes at the margins of the sheets, notably around the openings such as 10 and 11 and along the edges of the material.

The composition of the sheets constituting the electrodes and the electrolyte of the electrochemical generator in Figure 2 is now going to be considered.

According to a preferred mode of implementation of the invention, lithium is used in at least one of the electrodes of the casing material.

Preferably, the negative electrode is a lithium-based product, but this can also be an alloy like, for example, LiAI or an insertion compound like CLi.

Preferably again, the electrolyte is a solid material formed from a polymer mixed with a salt in solution in a polymer. In particular, a polyoxyethylene in li,. which salts such as LiAsF6, LCI04, LiCF3S03 and LiTFSI have been dissolved, 9 9 99 9 0* 0 0 0 0 *0 iP ~JE:: a5 ~i 'ra can be used. Such polymer-based solid electrolytes, for use in electrochemical generators notably with lithium, are known.

The positive electrode is formed from a polymer-based composite and a compound selected from the group NiS2, NiPS3, FePS3, V6013, V205, Mn02, (Bi203,PbO). NiO(OH), Pb02, Co304, and LiCoO2.

In one implementation mode of the invention, a rechargeable accumulator is achieved of about 10V and 800 mA/h, of 400 cm 2 total surface area, in four assemblies superimposed on 100 cm 2 arranged electrically in parallel, and with a tutal thickness of 4.8 mm. In each layer is found, for example: a negative electrode which is a composite sheet of LiAI powder mixed with carbon black in a plastic matrix of the type PEO.LiTFSI, a sheet of solid electrolyte of type PEO in solution in a LiTFSI type salt, a positive electrode which is a sheet containing 20% of the above electrolyte and 80% V6013.

Some measurements have been taken, concerning the effect of electrolmagnetic screening provided by the negative electrode; these are o: recorded in the following table: Case TSv Type R TSr TSb1 TSb2 A 60-120 Weak Video 1000 10 5 100 20 B 120-200 Weak Audio 600 104 100 C 200-250 Radiotelephone D 250 Radio Relay 50 104 100 In this table four types of measurements are shown, identified by the letters A to D, relating to equipments whose characteristics are stated in the 25 "Type" column. The table shows the value of intrirsic 'usceptibility of the typical circuit in this equipment TSv, the rnad resista',B of rh3 typical circuit R, its actual susceptibility TSr, which is the product of thu two preceding parameters, and the value of susceptibility achieved when the equipment is protected by a casing conforming to the invention, noted as TSb1 v n the electrode acting as the electrolmagnetic shield is not the outermost in the laminated material of the casing, and noted as TSb2 when the shield is on the outside.

A reduction of about 10" is seen in the susceptibility value obtained due

K.

xJ to the casing of the invention.

Figure 3 illustrates for its part results of measurement concerned with the immunity to electrolmagnetic noise from Schottky diode-type logic circuits at different frequencies. Measurements have been made of the minimum power which would have to radiate to cause a logic state inversion in circuits of this type, without protection (curve 31), in a casing according to the invention when the electrode acting as the electrolmagnetic shield is not outermost and in a casing according to the invention, when the screening is on the outside (curve 33).

These curves confirm the protective effect provided by the casing of the invention against external electrolmagnetic influences.

As might be expected, the invention is not only applicable in the case of electronic equipment casings, such as radiotelephones, but can be applied to advantage any time that it is necessary to provide a self-contained electrical power source and electrolmagnetic shielding together.

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99* a *o 9 6 4.

Claims

1. An electronic apparatus casing wherein at least a part of the casing comprises a laminated material including a plurality of sheets including, at least, one positive electrode and one negative electrode and an electrolyte separating the positive and negative electrodes, the material constituting an electrical energy storage device used as the power supply for the apparatus, at least one of the electrodes acting as an electromagnetic shield.

2. An electronic apparatus casi s claimed in claim 1, wherein said electrode acting as an electrolmagnetic shield extends substantially over the entire surface of the casing.

3. An electronic apparatus casing as claimed in claim 1 or 2, wherein said electrode acting as an electrolmagnetic shield is the outermost electrode in the material of the casing.

4. An electronic apparatus casing as claimed in claim 1 or 3, wherein said laminated material is formable and extends substantially over the entire surface of the casing.

5. An electronic apparatus casing as claimed in any one of claims 1 to 4, wherein lithium is used in at least one of the electrodes in the material of the casing. 20

6. An electronic apparatus casing as claimed in claim 5, wherein the electrolyte is a solid material formed from a polymer mixed with a salt in solution in a polymer.

7. An electronic apparatus casing as claimed in claim 6, wherein the electrolyte is a polyoxyethylene in which salts such as LiAsF6, LiCI04, LiCF3S03, LiTFSI have been dissolved.

8. An electronic apparatus casing as claimed in claim 6, wherein one of the electrode-forming sheets is formed from a polymer-based composite and a compound selected from the group NiS2, NiPS3, FePS3, V6012, V205, Mn02, (Bi203, PbO), NiO(OH), Pb02, Co304, LiCoO2.

9. An electronic apparatus casing as claimed in any one of claims 1 to 8, wherein the casing is formed at least in part from a hard plastic surrounding the laminated material.

10. An electronic apparatus casing substantially as herein described with tr -7 I 9 reference to Figures 1 3 of the accompanying drawings.

11. An electronic apparatus casing as claimed in any one of the preceding claims, wherein said electronic apparatus is a radiotelephone. DATED THIS FOURTH DAY OF JULY 1994 ALCATEL N.V. eeo to a o oooo .oo0o 100 os ABSTRACT An electronic apparatus casing of which at least a part (13, 14, 15) of the wall contains a laminated material comprising sheets having electrodes and an electrolyte separating the electrodes. The material constitutes an electrical energy storage device used as the power supply for a device, at least one of the electrodes acting moreover as an electromagnetic shield. Figure 1. **e C. C C C C