Surface modified cathode with improved lithium intercalation behavior

1. A surface modified cathode comprising 95 to 99 wt. % LiNi 0.4 Mn 0.4 Co 0.2 O 2 cathode powder and 1 to 5 wt. % metal oxide modifiers coated on the surface of the LiNi 0.4 Mn 0.4 Co 0.2 O 2 cathode powder, wherein the metal oxide modifiers are selected from the group consisting of In 2 O 3 , Cr 2 O 3 , ZnO and MgO.

2. The surface modified cathode as claimed in claim 1 , wherein the surface modified LiNi 04 Mn 04 Co 02 O 2 cathode powder exhibits appreciable capacity of ≥140 mAh g −1 at 1 C and ≥95 mAh g −1 at 3 C rate with a capacity retention ≥85%.

3. The surface modified cathode as claimed in claim 1 , wherein the thickness of the metal oxide modifiers is in a range of 1-10 nm.

4. A surface modified cathode comprising:

LiNi 0.4 Mn 0.4 Co 0.2 O 2 cathode powder; and

metal oxide modifiers coated on the surface of the LiNi 0.4 Mn 0.4 Co 0.2 O 2 cathode powder, wherein

the metal oxide modifiers are selected from the group consisting of Al 2 O 3 , Bi 2 O 3 , In 2 O 3 , Cr 2 O 3 , ZrO 2 , ZnO and MgO; and

a lattice constant c of structural parameters of the surface modified LiNi 0.4 Mn 0.4 Co 0.2 O 2 cathode powder ranges from 14.16 Å to less than 14.20 Å.

5. The surface modified cathode as claimed in claim 4 , wherein said surface modified cathode powder includes Bi 2 O 3 modifier coated on the surface of the LiNi 0.4 Mn 0.4 CO 0.2 O 2 cathode powder and exhibits appreciably high initial and steady-state cycling capacity of 196 and 175 mAh g −1 respectively with 89% capacity retention at C/10 rate.

6. The surface modified cathode as claimed in claim 4 , wherein weight percentage of the LiNi 0.4 Mn 0.4 CO 0.2 O 2 cathode powder is from 95 to 99 wt. % and weight percentage of the metal oxide modifiers is from 1 to 5 wt. %.

7. The surface modified cathode as claimed in claim 4 , wherein the surface modified LiNi 04 Mn 04 Co 02 O 2 cathode powder exhibits appreciable capacity of ≥140 mAh g −1 at 1 C and ≥95 mAh g −1 at 3 C rate with a capacity retention ≥85%.

8. The surface modified cathode as claimed in claim 4 , wherein the thickness of metal oxide modifiers is in a range of 1-10 nm.

9. A process for the preparation of surface modified LiNi 0.4 Mn 0.4 Co 0.2 O 2 cathode powder as claimed in claim 1 comprising the steps of:

i. dissolving LiCOOCH 3 2H 2 O, (CH 3 COO) 2 Ni.4H 2 O, (CH 3 COO) 2 Mn.4H 2 O, and (CH 3 COO) 2 Co.4H 2 O in 1:0.4:0.4:0.2 molar concentration respectively in water with stirring to get a homogeneous solution;

ii. adding 0.01M Cetyl Trimethyl Ammonium Bromide (CTAB) surfactant in the homogenous solution as obtained in step (i) with stirring followed by adding 1M citric acid as chelating agent to obtain a solution;

iii. adding 0.05N ammonium hydroxide solution in the solution as obtained in step (ii) to precipitate the respective metal oxide (in-situ formation) by adjusting the pH value of the solution between 8.5 to 9 followed by stirring and heating at temperature in the range of 70 to 80 ° C. continued to get a transparent gel;

iv. heating the gel as obtained in step (iii) at temperature in the range of 120 to 350° C. followed by calcination at temperature in the range of 500 to 900° C. to obtain LiNi 0.4 Mn 0.4 Co 0.2 O 2 powder;

v. adding 95 to 99% of the LiNi 0.4 Mn 0.4 CO 0.2 O 2 powder in water with a solution of 1-5 wt.% metal salt precursor followed by adding 0.01 to 0.05N ammonium hydroxide to obtain solution containing LiNi 0.4 Mn 0.4 CO 0.2 O 2 powder and in-situ formed metal oxide (Al 2 O 3 ) precipitate;

vi. evaporating the solution as obtained in step (v) at temperature in the range of 60 to 80° C. to obtain dried powder;

vii. heating the dried powders as obtained in step (vi) at temperature in the range of 450 to 550° C. for a period in the range of 1 to 8h to obtain surface modified LiNi 0.4 Mn 0.4 Co 0.2 O 2 cathode powder.

10. The process as claimed in claim 9 , wherein metal salt used is metal nitrate for Al, In and Cr metal acetate for Bi, Zr, Zn and Mg.

11. The process as claimed in claim 9 , wherein chelating agent used is citric acid.

12. A process for the preparation of surface modified LiNi 0.4 Mn 0.4 Co 0.2 O 2 cathode powder as claimed in claim 9 comprising the steps of:

i. dissolving LiCOOCH 3 .2H 2 O, (CH 3 COO) 2 Ni.4H 2 O, (CH 3 COO) 2 Mn.4H 2 O, and (CH 3 COO) 2 Co.4H 2 O in 1:0.4:0.4:0.2 molar concentration respectively in water with stirring to get a homogeneous solution;

ii. adding 0.01M Cetyl Trimethyl Ammonium Bromide (CTAB) surfactant in the homogenous solution as obtained in step (i) with stirring followed by adding 1M citric acid as chelating agent to obtain a solution;

iii. adding 0.05N ammonium hydroxide solution in the solution as obtained in step (ii) to precipitate the respective metal oxide (in-situ formation) by adjusting the pH value of the solution between 8.5 to 9 followed by stirring and heating at temperature in the range of 70 to 80° C. continued to get a transparent gel;

iv. heating the gel as obtained in step (iii) at temperature in the range of 120 to 350° C. followed by calcination at temperature in the range of 500 to 900° C. to obtain LiNi 0.4 Mn 0.4 CO 0.2 O 2 powder;

v. adding 95 to 99% of the LiNi 0.4 Mn 0.4 CO 0.2 O 2 powder in water with a solution of 1-5 wt.% metal salt precursor followed by adding 0.01 to 0.05N ammonium hydroxide to obtain solution containing LiNi 0.4 Mn 0.4 CO 0.2 O 2 powder and in-situ formed metal oxide (A 1 2 O 3 ) precipitate;

vi. evaporating the solution as obtained in step (v) at temperature in the range of 60 to 80° C. to obtain dried powder;

vii. heating the dried powders as obtained in step (vi) at temperature in the range of 450 to 550° C. for a period in the range of 1 to 8h to obtain surface modified LiNi 0.4 Mn 0.4 CO 0.2 O 2 cathode powder.

13. The process as claimed in claim 12 , wherein metal salt used is metal nitrate for A1, In and Cr metal acetate for Bi, Zr, Zn and Mg.

14. The process as claimed in claim 12 , wherein chelating agent used is citric acid.