An Energy Storage Device

Claims:We claim:

1) An energy storage device that stores charge by raising its voltage into the kV to MV or higher range.

2) The energy storage device as claimed in claim 1 comprising a single terminal capacitor or an array of single terminal capacitors (101) embedded in dielectric materials (102) that can store a lot of charge at high voltage to increase energy storage density.

3) The energy storage device as claimed in claim 2 wherein the said single terminal capacitor (101) is a sphere.

4) The energy storage device as claimed in claim 2 wherein the said single terminal capacitor (101) is made of metal or semiconductors.

5) The energy storage device as claimed in claim 2 wherein the said dielectric materials (102) are of high strength.

6) The energy storage device as claimed in claim 2 further comprising a reference terminal far away from the single terminal capacitor (101).

7) The energy storage device as claimed in claim 2 wherein the said capacitor (101) is charged by a current source and not a voltage source.

8) The energy storage device as claimed in claim 2 wherein the array of single terminal capacitors (101) are connected in parallel in order to multiply energy storage density

9) The energy storage device as claimed in claim 3 wherein the said sphere (101) is hollow or solid.

10) The energy storage device as claimed in claim 3 wherein the electric connections between the said spheres (101) are made on the inside wall of the spheres. , Description:FIELD OF THE INVENTION

[0001] The present invention relates to an energy storage device.

BACKGROUND OF THE INVENTION

[0002] Energy storage (Density, Cost) is a major issue today. For high power applications, batteries appear to receive more attention as compared to capacitors perhaps due to their higher energy densities. Energy storage is required at all levels from small gadgets to large power distribution grids. Thinking in terms of capacitors, tomorrow’s electric vehicles need 50kF or more of capacitance @48 Volts. Energy storage technology is a major bottleneck for the large scale commercialization of Electric Vehicles today. Electric Vehicle energy storage devices need to handle high power and high energy capacity within a limited space and weight and at an affordable price. Batteries typically have high energy density. Batteries work on movement of ions through electrolyte. Capacitors typically have fast charge/discharge rates. Capacitors work on movement of charges. Many research groups in the world are working on Lithium ion technologies and Supercapacitors today. However energy density of supercapacitors is still far lower than that of Li ion. If high energy density capacitors, even beyond supercapacitors, can be created, then they would potentially score over batteries due to their significantly faster charging and discharging rates.

[0003] The capacitance C of a parallel plate capacitor is given by where e0 is the absolute permittivity, er is the relative permittivity, A is the area of the parallel plates, and d is the distance between the plates. At 48Volt, best case C with today's technology would be roughly in the milliFarads range which is about 106 fold lower than required.

[0004] There is recognized need in the art to either improve capacitance by a factor of 106 or to employ a device that is entirely different from a parallel plate capacitor and hence not bound by the same physics. The present invention fulfills this long standing need in the art.

SUMMARY OF THE INVENTION

[0005] An object of the present invention is to provide an energy storage device which can increase energy storage capacity in a small space.

[0006] Another object of the present invention is to provide an energy storage device which can be used all the way from small gadgets such as cell phones to Electric Vehicles and eventually in power distribution applications.

[0007] Accordingly, to meet the objects of the invention, disclosed herein is an energy storage device that stores charge by raising its voltage into the kiloVolt (kV) to MegaVolt (MV) or higher range. The energy storage device comprises a single terminal capacitor or an array of single terminal capacitors embedded in dielectric materials that can store a lot of charge at high voltage to increase energy storage density. The said single terminal capacitor may be a sphere which could be hollow or solid. The said single terminal capacitor may be made of metal or semiconductors. The said dielectric materials are preferably of high strength and the said capacitor is charged by a current source and not a voltage source.

[0008] According to a further aspect of the invention, the energy storage device comprises a reference terminal far away from the single terminal capacitor.

[0009] According to a further aspect of the invention, the electric connections between the said spheres are made on the inside wall of the spheres.

BRIEF DESCRIPTION OF THE DRAWINGS

[00010] Referring now to the drawings wherein the showings are for the purpose of illustrating embodiments of the inventions only, and not for the purpose of limiting the same.

[00011] Fig. 1 shows an array of metal spheres embedded in a dielectric material in accordance with an exemplary embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[00012] Definitions unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[00013] The present invention will be described herein below with reference to the accompanying drawings. The present invention, in accordance with an embodiment of the invention, discloses an energy storage device that stores charge by raising its voltage into the kV to MV or higher range.

[00014] In accordance with an embodiment of the invention, an array of single terminal capacitors (101) embedded in a dielectric material (102) is shown in Fig. 1. Referring to Fig. 1, the energy storage device comprises a single terminal capacitor or an array of single terminal capacitors (101) embedded in dielectric materials (102) that can store a lot of charge at high voltage in order to increase energy storage capacity. A sphere is one example of a single terminal capacitor suitable for use in an embodiment of the present invention and acts as an energy storage device. The sphere (101) may be made of metal or semiconductor. Other charge storage materials and/or geometries may be used, consistent with the spirit of the invention. The spheres (101) may be hollow or solid. The spheres (101) need to be charged from a charge or current source and not by a voltage source like a conventional battery. The sphere (101) stores charges, not ions and acts as a capacitor. The sphere (101) is a single terminal capacitor and there is no second terminal. Theoretically, the sphere can store “infinite” charge if the dielectric medium around it is perfect. In practice, the amount of charge that can be stored is bound primarily by the dielectric strength of the material surrounding the sphere. Therefore, the dielectric materials (102) are preferably of high strength.

[00015] In a preferred embodiment, the array of single terminal capacitors (101) is connected in parallel within the dielectric matrix in order to multiple energy storage density.

[00016] Even at low capacitance, the sphere can store any amount of charge by raising its voltage. V = Q/C.

[00017] Spheres are preferred due to the absence of sharp corners, but other shapes may be possible.

[00018] No second terminal implies any voltage is possible. Mathematically, the second terminal is assumed to be at infinity. According to a further aspect of the invention, the energy storage device comprises a reference material far away from the single terminal capacitor.

[00019] Conventional parallel plate capacitors (including variants such supercapacitors/EDLCs) are limited by voltage.

[00020] The “read-out” is a power circuit that charges and discharges at high voltage storage device – in effect, a circuit that handles a “charge” source.

[00021] To illustrate the concept, consider a cell phone application: Typical mobile battery 3.7 Volts Typcal mAH 2000 mAH Calculate Wh 7.4 Wh Convert Wh to Joules 26640 Joules

[00022] In accordance with an embodiment of the present invention, assume a 20mm x 20mm chip area – this can contain 250,000 20 µm spheres

[00023] Total capacitance is of the order of 3 nFarad.

[00024] Some microfabrication process development may be possible to increase capacitance further.

[00025] It gives a voltage in the range of 1-5 MV. This will need at least 1mm of a material such as high quality quartz insulator.

[00026] Similar to quartz, other materials with high dielectric strength may be used.

[00027] The foregoing description is for preferred embodiments of the present invention. It should be appreciated that these embodiments are described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.

[00028] Other modifications will be apparent to those skilled in the art and, therefore, the invention is defined in the claims.