High energy lithium ion secondary battery with improved lifetime and energy density

1. A rechargeable lithium-ion cell, comprising:

an anode material,

a cathode material, and

an electrolyte,

wherein the anode material comprises a composite consisting of nanoporous silicon encapsulated by carbon nanotubes, wherein an average particle diameter of the nanoporous silicon is in the range of about 10 to 20 nm,

wherein the cathode material comprises a concentration gradient nickel-based lithium metal oxide represented by the following formula,

Li a Ni x Co y M z O 2 ,

wherein 0.9<a<1.1, 0.4<x<1, 0<y<0.5, 0<z<0.5 and x+y+z=1, and

wherein M is at least one selected from the group consisting of Mg, Ca, Sr, Ba, Ti, Zr, Nb, Mo, W, Zn, Al, Si, Mn, Cr, Fe, Mg, Sr, V, and a rare earth element.

2. The rechargeable lithium-ion cell according to claim 1 , wherein the concentration gradient is a full-concentration gradient (FCG) with or without shell, a two-slope full-concentration gradient (TSFCG) with or without shell, or a core-shell-gradient (CSG) with or without shell.

3. The rechargeable lithium-ion cell according to claim 1 , wherein M is Mn or Al.

4. The rechargeable lithium-ion cell according to claim 1 , wherein the nickel-based lithium metal oxide is a compound selected from the group consisting of Li[Ni0.85Co0.05Mn0.10]O2, Li[Ni0.80Co0.05Mn0.15]O2 and Li[Ni0.8Co0.15Al10.05]O2.

5. The rechargeable lithium-ion cell according to claim 1 , wherein the cathode material is comprised of Li[Ni0.85Co0.05Mn0.10]O2 containing a two-sloped full concentration gradient (TSFCG).

6. The rechargeable lithium-ion cell according to claim 1 , wherein the silicon and carbon nanotubes composite comprises at least one secondary particle having at least two agglomerates of primary particles, wherein an average particle diameter of each primary particle is in the range of about 100 nm to about 500 nm, wherein an average particle diameter of the at least one secondary particle is in the range of about 2 to 3 μm.

7. The rechargeable lithium-ion cell according to claim 1 , wherein an average particle diameter of the nanoporous silicon is in the range of about 10 to 15 nm.

8. The rechargeable lithium-ion cell according to claim 1 , wherein the nanoporous silicon and the carbon nanotubes are mixed by ball-milling at a weight ratio of 85:15.

9. The rechargeable lithium-ion cell according to claim 1 , wherein the nickel-based lithium metal oxide present in the cathode material is in amount of about 85 to 97% by weight.

10. The rechargeable lithium-ion cell according to claim 1 , wherein the silicon and carbon nanotubes composite present in the anode material is in an amount of about 60 to 95% by weight.

11. The rechargeable lithium-ion cell according to claim 1 , wherein the cathode material includes a conductive additive and a binder.

12. The rechargeable lithium-ion cell according to claim 1 , wherein the anode material includes a conductive additive and a binder.

13. A battery containing at least one rechargeable lithium-ion cell according to claim 1 .