A battery cell including: an anode configured to operate as a source of cations during discharge of the battery cell; and an electrolyte configured to transport the cations from the anode to the a cathode during discharge of the battery cell, wherein the cathode includes material that is configured to enable the reversible insertion of transported cations during discharge of the battery cell and that has optical properties that are dependent upon cation insertion and that is viewable by a user.
1. A battery cell comprising;
an anode configured to operate as a source of cations during discharge of the battery cell;
a cathode; and
an electrolyte configured to transport the cations from the anode to the cathode during discharge of the battery cell,
wherein the cathode comprises material that is configured to enable the reversible insertion of transported cations during discharge of the battery cell and to have optical properties that are dependent upon cation insertion and that is viewable by a user and the material comprises Vanadium Oxide with a gyroid nano-structure.
2. A battery as claimed in claim 1 , wherein reversing of the insertion of transported cations occurs during charging of the battery cell, wherein the material has a first state having a first optical property when the battery cell is in a charged state, has a second state having a second optical property when the battery cell is in a discharged state, and has a third state having a third optical property when the battery cell is in a partially charged state.
3. A battery as claimed in claim 1 , wherein the material is configured to enter any one of a plurality of charging dependent states having different associated optical properties as a result of charging/discharging the battery cell and the material is configured to remain in a charging state without input of energy until additional charging or discharging changes the charging state.
4. A battery as claimed in claim 1 , wherein the battery cell comprises a housing having an exterior housing portion that enables a user, by visual inspection through the exterior housing portion, to identify a change in the optical properties of the material.
5. A battery as claimed in claim 1 , wherein the cathode comprises a translucent or transparent substrate that enables a user, by visual inspection through the substrate, to identify a change in the optical properties of the material.
6. A battery as claimed in claim 5 , wherein the cathode comprises a translucent or transparent conductive electrode film that is located between the substrate and the material.
7. A battery as claimed in claim 1 , wherein the battery cell has a exterior surface area and wherein the material is viewable by a user through at least 20% of the exterior surface area.
8. A battery as claimed in claim 1 , wherein the color of the material is dependent upon cation insertion.
9. A battery as claimed in claim 1 , wherein the material remains translucent or transparent upon cation insertion.
10. A battery as claimed in claim 1 , wherein the material comprises a plurality of elongate nano-structures.
11. A battery as claimed in claim 1 , wherein the anode is a lithium based anode and the cations are lithium ions.
12. A battery as claimed in claim 11 , wherein the battery is an organo-inorganic hybrid and the electrolyte is a polymer.
13. A battery as claimed in claim 1 , wherein the electrolyte is transparent or translucent.
14. An apparatus comprising:
electrical components and a battery as claimed in claim 1 for providing power to the electrical components.
15. A method comprising:
manufacturing a battery by combining
a cathode comprising material that is configured to enable the reversible insertion of transported cations during discharge of the battery cell and that has optical properties that are dependent upon cation insertion, wherein the material comprises Vanadium Oxide with a gyroid nano-structure;
an anode configured to operate as a source of cations during discharge of the battery cell; and
an electrolyte configured to transport the cations from the anode to the cathode during discharge of the battery cell, such that at least a portion of the material is viewable by a user.
16. A method as claimed in claim 15 wherein the cathode is formed by:
a) forming a vanadium (V) oxide sol from a vanadate reagent, acidic ion exchange resin and water;
b) heating;
c) leaving to stand and form nanofibres of vanadium (V) oxide; and
d) depositing nanofibres on a substrate.
17. A method comprising:
forming an electrode by:
a) forming a vanadium (V) oxide sol from a vanadate reagent, acidic ion exchange resin and water;
b) heating;
c) leaving to stand and form nanofibres of vanadium (v) oxide; and
d) depositing nanofibres on a substrate to form Vanadium Oxide with a gyroid nano-structure.
18. A method as claimed in claim 17 , wherein the vanadate reagent is ammonium meta-vanadate NH 4 VO 3 .
19. A method as claimed in claim 18 , wherein the ratio by weight of ammonium meta-vanadate: acidic ion exchange resin: water is approximately 1:10:200.
20. A battery as claimed in claim 1 , wherein the optical properties of the material comprise any one of the following:
a change of polarization, transmission, reflection and brightness of the material.