Hybrid nano-filament anode compositions for lithium ion batteries

1. A lithium secondary battery comprising a positive electrode, a negative electrode comprising a hybrid nano-filament composition which is capable of absorbing and desorbing lithium ions, and a non-aqueous electrolyte disposed between said negative electrode and said positive electrode, wherein said hybrid nano-filament composition comprises:

a) An aggregate of nanometer-scaled, electrically conductive carbon filaments that are interconnected, intersected, or percolated to form a porous, electrically conductive filament network comprising interconnected pores for accommodating said non-aqueous electrolyte, wherein said nanometer-scaled, electrically conductive carbon filaments have an elongate dimension and a first transverse dimension, which is a diameter or a thickness, said first transverse dimension being less than 500 nm and an aspect ratio of said elongate dimension to said first transverse dimension greater than 10, and wherein said nanometer-scaled, electrically conductive carbon filaments are carbonized electro-spun fibers; and

b) Micron- or nanometer-scaled coating that is deposited on a surface of said nanometer-scaled, electrically conductive carbon filaments, wherein said coating deposited on said nanometer-scaled, electrically conductive carbon filaments comprises an negative active material capable of absorbing and desorbing lithium ions and said coating has a thickness less than 20 μm;

wherein said nanometer-scaled, electrically conductive carbon filaments enable said deposited coating to freely undergo strain relaxation in transverse directions so that said coating does not lose contact with said nanometer-scaled, electrically conductive carbon filaments during charge/discharge cycles of the lithium secondary battery, wherein said coating is wrapped around said nanometer-scaled, electrically conductive carbon filament, wherein said coating deposited on said nanometer-scaled, electrically conductive carbon filaments comprises said negative active material selected from the group consisting of:

i. germanium (Ge), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), and cadmium (Cd);

ii. alloys or intermetallic compounds of Ge, Sb, Bi, Zn, Al, or Cd with other elements, wherein said alloys or compounds are stoichiometric or non-stoichiometric;

iii. oxides, carbides, nitrides, sulfides, phosphides, selenides, and tellurides of Ge, Sb, Bi, Zn, Al, I or Cd, and their mixtures or composites; and

iv. combinations thereof.

2. The lithium secondary battery of claim 1 wherein said nanometer-scaled, electrically conductive carbon filaments have a transverse dimension smaller than 100 nm or said coating has a thickness smaller than 1 μm.

3. The lithium secondary battery of claim 1 wherein said coating has a thickness smaller than 200 nm.

4. The lithium secondary battery of claim 1 wherein said nanometer-scaled, electrically conductive carbon filaments comprise an electrically conductive, electro-spun polymer fiber, electro-spun polymer nanocomposite fiber comprising a conductive filler, nano carbon fiber obtained from carbonization of an electro-spun polymer fiber, electro-spun pitch fiber, or a combination thereof.

5. The lithium secondary battery as defined in claim 1 wherein the coating comprises Ge as a primary element with a Ge content no less than 50% by weight based on the total weight of the coating.

6. The lithium secondary battery as defined in claim 2 wherein the coating comprises Ge as a primary element with Ge content no less than 50% by weight based on the total weight of the coating.

7. The lithium secondary battery as defined in claim 1 wherein the coating comprises an element selected from Ge, Cd, Sb, Bi, Zn, or a combination thereof.

8. The lithium secondary battery according to claim 1 , wherein said positive electrode comprises lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium iron phosphate, lithium vanadium phosphate, or a combination thereof.

9. The lithium secondary battery as defined in claim 1 , wherein said hybrid nano-filament composition further comprises a binder material selected from a polymer, coal tar pitch, petroleum pitch, meso-phase pitch, coke, or a derivative thereof.

10. The lithium secondary battery as defined in claim 1 , wherein said hybrid nano-filament composition provides a specific capacity of no less than 1,000 mAh per gram of the anode composition.

11. The lithium secondary battery as defined in claim 1 , wherein said hybrid nano-filament composition provides a specific capacity of no less than 2,000 mAh per gram of the anode composition.

12. The lithium secondary battery as defined in claim 1 , wherein said hybrid nano-filament composition provides a specific capacity of no less than 3,000 mAh per gram of the anode composition.

13. An electrochemical cell electrode comprising a hybrid nano-filament composition, said hybrid nano-filament composition comprising:

a) an aggregate of nanometer-scaled, electrically conductive graphene platelets that are interconnected, intersected, or percolated to form a porous, electrically conductive graphene platelets network comprising interconnected pores, wherein said nanometer-scaled, electrically conductive graphene platelet has a length and a thickness, said thickness being no greater than 100 nm, and a length-to-thickness aspect ratio no less than 10; and

b) micron- or nanometer-scaled coating that is deposited on a surface of said nanometer-scaled, electrically conductive graphene platelets, wherein said coating deposited on said nanometer-scaled, electrically conductive graphene platelets comprises an anode active material selected from the group consisting of:

i. germanium (Ge), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), and cadmium (Cd);

ii. alloys or intermetallic compounds of Ge, Sb, Bi, Zn, Al, or Cd with other elements, wherein said alloys or compounds are stoichiometric or non-stoichiometric;

iii. oxides, carbides, nitrides, sulfides, phosphides, selenides, and tellurides of Ge, Sb, Bi, Zn, Al, or Cd, and their mixtures or composites; and

iv. combinations thereof;

wherein said nanometer-scaled, electrically conductive graphene platelets enable said deposited coating to freely undergo strain relaxation in transverse directions so that said coating does not lose contact with said nanometer-scaled, electrically conductive graphene platelets during charge/discharge cycles of the electrochemical cell, wherein said coating is wrapped around said nanometer-scaled, electrically conductive graphene platelet.