1. A method for determining degradation of a thermoplastic, the method comprising:
illuminating the thermoplastic, for a period of time, with light having a peak intensity centered at a wavelength from about 400 nm to about 500 nm and an irradiance from about 400 Wm2 to about 150,000 Wm2;
maintaining the average temperature of the thermoplastic at a temperature from about 23\xb0 C. to about 175\xb0 C. during the period of time; and
repeating the illuminating and maintaining steps for a plurality of successive periods of time.
2. The method of claim 1, further comprising measuring the temperatures of at least two samples of the thermoplastic and calculating an average temperature of the thermoplastic using the temperatures of the at least two samples of the thermoplastic.
3. The method of claim 1, further comprising evaluating the degradation of the thermoplastic after each successive period of time.
4. The method of claim 1, further comprising repeating the illuminating, maintaining and evaluating steps for a plurality of successive time periods for a plurality of different thermoplastic formulations; and comparing the degradation of the plurality of different thermoplastic formulations with one another.
5. The method of claim 4, wherein evaluating the degradation comprises visually inspecting the thermoplastic measuring a degree of discoloration of the thermoplastic, or both.
6. The method of claim 1, wherein the average temperature of the thermoplastic is maintained at a temperature from about 90\xb0 C. to about 130\xb0 C.
7. The method of claim 5, wherein measuring the degree of discoloration of the thermoplastic comprises:
(1) illuminating the thermoplastic with white light, a portion of the white light being transmitted through the thermoplastic; and
generating a transmission spectrum from the portion of the white light transmitted through the thermoplastic; or
(2) illuminating the thermoplastic with white light, a portion of the white light being reflected from the thermoplastic; and
generating a reflectance spectrum of the portion of the white light reflected from the thermoplastic;
or (1) and (2).
8. The method of claim 5, further comprising comparing the degrees of discoloration measured after successive periods of time with one another.
9. A method for determining a discoloration rate of a polycarbonate, the method comprising:
illuminating the polycarbonate with light having a peak intensity centered at a wavelength from about 400 nm to about 500 nm and an irradiance from about 400 Wm2 to about 150,000 Wm2 for a first period of time; and
maintaining the average temperature of the polycarbonate at a temperature from about 23\xb0 C. to about 175\xb0 C. during the first period of time.
10. The method of claim 10, further comprising measuring the temperatures of at least two samples of the polycarbonate and calculating an average temperature of the thermoplastic using the temperatures of the at least two samples of the polycarbonate.
11. The method of claim 9, further comprising evaluating a degree of discoloration of the polycarbonate after the first period of time has elapsed.
12. The method of claim 9, further comprising:
repeating said illuminating, maintaining and measuring steps for a plurality of different polycarbonate formulations; and
comparing the discoloration of said plurality of different polycarbonate formulations with one another.
13. The method of claim 9, wherein evaluating said degradation comprises visually inspecting the polycarbonate.
14. The method of claim 9, wherein evaluating the degradation comprises measuring a degree of discoloration of the polycarbonate.
15. The method of claim 14, wherein measuring the degree of discoloration of the polycarbonate comprises:
(1) illuminating the polycarbonate with white light, a portion of the white light being transmitted through the polycarbonate; and
generating a transmission spectrum from the portion of the white light transmitted through the polycarbonate; or
(2) illuminating the transparent polycarbonate with white light, a portion of the white light being reflected from the transparent polycarbonate; and
generating a reflectance spectrum of the portion of the white light reflected from the transparent polycarbonate;
or (1) and (2).
16. The method of claim 9, further comprising:
repeating the illuminating and maintaining steps for a second period of time;
after the second period of time has elapsed, measuring a degree of discoloration of the transparent polycarbonate.
17. The method of claim 16, further comprising comparing the degree of discoloration measured after the first period of time with the degree of discoloration after the second period of time.
18. A method for determining a discoloration rate of a transparent polycarbonate, the method comprising:
illuminating the transparent polycarbonate with light having a peak intensity centered at a wavelength from about 400 nm to about 500 nm and an irradiance from about 50,000 Wm2 to about 150,000 Wm2 for a period of time;
maintaining the average temperature of the transparent polycarbonate at a temperature from about 23\xb0 C. to about 175\xb0 C. during the first period of time;
repeating the illuminating and maintaining steps for a plurality of successive periods of time; and
after each the successive period of time, measuring a degree of discoloration of the transparent polycarbonate.
19. The method of claim 18, further comprising measuring temperatures of at least two samples of the transparent polycarbonate; and calculating an average temperature of the transparent polycarbonate using the temperatures of the at least two samples of the transparent polycarbonate.
20. The method of claim 18, further comprising:
repeating the illuminating, maintaining and measuring steps for a plurality of successive time periods for a plurality of different transparent polycarbonate formulations; and
comparing the discoloration of the plurality of different transparent polycarbonate formulations with one another.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An electrode active material comprising: a core layer capable of repeating lithium intercalationdeintercalation; an amorphous carbon layer; and a crystalline carbon layer, successively, wherein the core layer comprises at least two core particles.
2. The electrode active material according to claim 1, wherein the core particles comprise a metal or metalloid capable of repeating lithium intercalationdeintercalation.
3. The electrode active material according to claim 1, wherein the core particles comprise at least one metal or metalloid selected from the group consisting of Si, Al, Sn, Sb, Bi, As, Ge and Pb, or an alloy thereof.
4. The electrode active material according to claim 1, wherein the core particles have an average particle diameter of 0.01\u02dc50 \u03bcm.
5. The electrode active material according to claim 1, wherein the crystalline carbon layer comprises sheet-like carbon layer units, and c-axis direction of the sheet-like carbon layer units is perpendicular to tangent direction of the electrode active material particle.
6. The electrode active material according to claim 1, wherein the core layer, the amorphous carbon layer and the crystalline carbon layer are in a ratio of core layer:amorphous carbon layer:crystalline carbon layer of 70\u02dc30 parts by weight:0.1\u02dc50 parts by weight:29.9\u02dc70 parts by weight.
7. The electrode active material according to claim 1, wherein the crystalline carbon layer has an interlayer spacing d002 of 0.3354\u02dc0.35 nm and a thickness of 1\u02dc10 microns.
8. The electrode active material according to claim 1, wherein the amorphous carbon layer has an interlayer spacing d002 of 0.34 nm or more, and a thickness of 5 nm or more.
9. A secondary battery comprising an electrode active material,
wherein the electrode active material comprising: a core layer capable of repeating lithium intercalationdeintercalation; an amorphous carbon layer; and a crystalline carbon layer, successively, wherein the core layer comprises at least two core particles.
10. The secondary battery according to claim 9, wherein the core particles comprise a metal or metalloid capable of repeating lithium intercalationdeintercalation.
11. The secondary battery according to claim 9, wherein the core particles comprise at least one metal or metalloid selected from the group consisting of Si, Al, Sn, Sb, Bi, As, Ge and Pb, or an alloy thereof.
12. The secondary battery according to claim 9, wherein the crystalline carbon layer comprises sheet-like carbon layer units, and c-axis direction of the sheet-like carbon layer units is perpendicular to tangent direction of the electrode active material particle.
13. The secondary battery according to claim 9, wherein the core layer, the amorphous carbon layer and the crystalline carbon layer are in a ratio of core layer:amorphous carbon layer:crystalline carbon layer of 70\u02dc30 parts by weight:0.1\u02dc50 parts by weight:29.9\u02dc70 parts by weight.
14. The secondary battery according to claim 9, wherein the crystalline carbon layer has an interlayer spacing d002 of 0.3354\u02dc0.35 nm and a thickness of 1\u02dc10 microns.
15. The secondary battery according to claim 9, wherein the amorphous carbon layer has an interlayer spacing d002 of 0.34 nm or more, and a thickness of 5 nm or more.
16. A method for preparing the electrode active material as defined in claim 1, the method comprising: a first step of mixing a metal or metalloid forming a core layer with crystalline carbon; and a second step of carrying out mechanical alloying of the mixture obtained from the first step in a Mechano Fusion system in the presence of balls.
17. The method according to claim 16, wherein the metal or metalloid and the crystalline carbon are mixed in the first step in a ratio of metal or metalloid:crystalline carbon of 70\u02dc30 parts by weight:30\u02dc70 parts by weight.
18. The method according to claim 16, wherein the balls and the mixture of the first step are mixed in the second step in a ratio of balls:mixture of the first step of 50\u02dc98 parts by weight:50\u02dc2 parts by weight.
19. The method according to claim 16, wherein the balls used in the second step include stainless steel balls or zirconia balls.
20. The method according to claim 16, wherein the balls used in the second step have a diameter of 0.1\u02dc10 mm.