Surface modification agents for lithium batteries

1. An active material for an electrochemical device wherein a surface of the active material is modified by a surface modification agent; wherein the surface modification agent is a silane, and the silane has Formula I, II, III, IV, or a mixture of any two or more thereof:

wherein:

X 1 , X 2 , X 3 and X 4 are independently —Cl or —Br;

R 1 , R 2 , and R 3 are independently a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, an OR 5 group, or a group of Formula V;

R 5 is a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group; and

the surface modification agent is chloro[2-[2-(2-methoxyethoxy)ethoxy]ethoxy]dimethylsilane.

2. The active material of claim 1 , wherein the surface of the active material is treated with plasma.

3. The active material of claim 2 , wherein the plasma is generated by applying radiofrequency discharge on fluorine-based gas.

4. The active material of claim 3 , wherein the fluorine-based gas is F 2 , C q″ F 2q″+2 , C q″ F 2q″ , or C q″ F 2q″−2 and q″ is an integer ranging from 1 to 20.

5. A negative electrode comprising the active material of claim 1 .

6. A positive electrode comprising the active material of claim 1 .

7. The active material of claim 1 , wherein the active material is a positive electrode active material selected from the group consisting of spinel, olivine, carbon-coated olivine, LiFePO 4 , Li x′ M′ y′ M″ z′ PO 4 , Li 1+x″ Ni α Mn β Co γ Met′ δ O 2−z″ , F z″ , A n″ B 2 (XO 4 ) 3 , vanadium oxide, and mixtures of any two or more thereof; and further wherein

M′ is selected from the group consisting of V, Cr, Mg, Fe, Co, and Ni;

M″ is selected from group consisting of IIA, IIIA, IVA, VA, VIA and IIIB metals having an ionic radius less than the ionic radius of Fe 2+ ;

Met' is selected from the group consisting of Mg, Zn, Al, Ga, B, Zr, and Ti; and

0≦x′≦1, 0≦y′≦1, 0≦z′≦1, 0≦x″≦0.4, 0≦α≦1,0≦β≦1, 0≦γ≦2, 0 ≦δ≦0.2 0≦z″≦0.5, and 0≦n″≦3.

8. The active material of claim 1 , wherein the active material is a negative electrode material selected from the group consisting of graphite, amorphous carbon, Li 4 Ti 5 O 12 , M 1−x A x Li 2−y B y Ti 6−z C z O 14−t Q t , tin alloys, silicon alloys, intermetallic compounds, lithium metal, or mixtures of any two or more such materials; and further wherein:

M is selected from the group consisting of Ba, Sr, Ca, Mg, Pb, and Sn;

0≦x≦0.5, 0 ≦y≦0.5, 0≦z≦0.5, 0<t≦0.5;

each of A, B and C are independently at least one divalent, trivalent or tetravalent metal; and

Q is a monovalent or divalent anion.

9. An electrochemical device comprising:

a positive electrode;

an negative electrode; and

non-aqueous electrolyte;

wherein the negative electrode and/or the positive electrode comprises a surface modification agent, and further wherein a surface of the negative electrode and/or the positive electrode is modified by the surface modification agent;

wherein the surface modification agent is a silane, and the silane has Formula I, II, III, IV, or a mixture of any two or more thereof:

wherein:

X 1 , X 2 , X 3 and X 4 are independently —Cl or —Br;

R 1 , R 2 , and R 3 are independently a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, an OR 5 group, or a group of Formula V;

R 5 is a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group; and

the surface modification agent is chloro[2-[2-(2-methoxyethoxy)ethoxy]ethoxyl]dimethylsilane.