Curved battery-pack devices and accessories

1. A curved battery cell comprising:

a positive terminal;

a negative terminal;

one or more curved electrodes comprising at least one curved surface having a non-uniform radius of curvature substantially matching a non-uniform radius of curvature of one or more spline curves that substantially match average body contours of one or more individuals; and

an outer case encasing the one or more curved electrodes and exposing the positive terminal and the negative terminal.

2. The curved battery cell of claim 1 , wherein the one or more spline curves are defined by:

a starting point;

an ending point;

a midpoint;

a first radius at the starting point;

a second radius at the ending point; and

a third radius at the midpoint, wherein the first radius, the second radius, and the third radius are different.

3. The curved battery cell of claim 1 , wherein the one or more spline curves are defined by:

a first curve segment having a varying radius of curvature; and

a second curve segment having a constant radius of curvature.

4. The curved battery cell of claim 1 , wherein the one or more spline curves are defined by multiple control points.

5. The curved battery cell of claim 1 , wherein the one or more spline curves substantially match average head contours of the one or more individuals.

6. The curved battery cell of claim 1 , wherein the curved surface of the one or more curved electrodes is shaped to conform to a portion of a strap of a head-mounted display system when the head-mounted display system is worn and the portion of the strap conforms to a user's head.

7. The curved battery cell of claim 1 , wherein:

the curved surface of the one or more curved electrodes comprises at least a first area and a second area;

the first area has a first radius of curvature;

the second area has a second radius of curvature; and

the first radius of curvature and the second radius of curvature are different.

8. The curved battery cell of claim 1 , wherein:

the curved surface of the one or more curved electrodes comprises at least a first area and a second area;

the first area has a constant radius of curvature; and

the second area has a varying radius of curvature.

9. The curved battery cell of claim 1 , wherein the curved surface of the one or more curved electrodes is an inner surface having a non-uniform inner radius within a range of between 80 millimeters and 95 millimeters.

10. The curved battery cell of claim 1 , wherein the curved surface of the one or more curved electrodes is an inner surface having a non-uniform inner radius within a range of between 70 millimeters and 125 millimeters.

11. A curved battery pack comprising:

a first curved battery cell comprising one or more curved electrodes having a first outer surface, wherein the first outer surface of the one or more curved electrodes has a first non-uniform curvature substantially matching a non-uniform curvature of a first one or more spline curves that substantially match average body contours of one or more individuals; and

a second curved battery cell comprising one or more additional curved electrodes having a second outer surface, wherein the second outer surface of the one or more additional curved electrodes has a second non-uniform curvature substantially matching a non-uniform curvature of a second one or more spline curves.

12. The curved battery pack of claim 11 , wherein at least one of the first one or more spline curves is defined by:

a first curve segment having a varying radius of curvature; and

a second curve segment having a constant radius of curvature.

13. The curved battery pack of claim 11 , wherein the first non-uniform curvature and the second non-uniform curvature are equal.

14. The curved battery pack of claim 11 , wherein the first non-uniform curvature and the second non-uniform curvature are mirrored.

15. The curved battery pack of claim 11 , wherein at least one of the first one or more spline curves is defined by multiple control points.

16. The curved battery pack of claim 11 , wherein the first outer surface and the second outer surface are inner surfaces shaped to face toward one or more users' bodies.

17. The curved battery pack of claim 11 , further comprising a bendable joining member coupling the first curved battery cell to the second curved battery cell.

18. A method comprising:

placing a flat electrode assembly comprising one or more flat electrodes between matching spline surfaces of an upper jig and a lower jig, the matching spline surfaces having curvatures that substantially match a non-uniform curvature of the one or more spline curves that substantially match average body contours of one or more individuals;

curving the flat electrode assembly, including the one or more flat electrodes, by pressing the flat electrode assembly between the spline surfaces of the upper jig and the lower jig;

separating the upper jig from the lower jig; and

removing the curved electrode assembly, including the one or more curved electrodes, from the upper jig and the lower jig.

19. The method of claim 18 , wherein placing a flat electrode assembly between the matching spline surfaces of the upper jig and the lower jig comprises placing a flat cuboidal electrode assembly between the upper jig and the lower jig.

20. The method of claim 18 , wherein the one or more flat electrodes comprise a plurality of stacked electrodes.