Precursor and method for preparing Ni based Li transition metal oxide cathodes for rechargeable batteries
A crystalline precursor compound is described for manufacturing a lithium transition metal based oxide powder usable as an active positive electrode material in lithium-ion batteries, the precursor having a general formula Li 1−a ((Ni z (Ni 1/2 Mn 1/2 )y Co x ) 1−k A k ) 1+a O 2 , wherein x+y+z=1, 0.1≤x≤0.4, 0.25≤z≤0.55, A is a dopant, 0≤k≤0.1, and 0.04≤a≤0.50, wherein the precursor has a crystalline size L expressed in nm, with 77−(67*z)≤L≤97−(67*z). Also a method is described for manufacturing a positive electrode material having a general formula Li 1−a′ ((Ni z (Ni 1/2 Mn 1/2 ) y Co x ) 1−k A k ) 1−a′ O 2 , wherein x+y+z=1, 0.1≤x≤0.4, 0.25≤z≤0.55, A is a dopant, 0≤k≤0.1, and 0.01≤a′≤0.10 by sintering the crystalline precursor compound in an oxidizing atmosphere at a temperature T between 800 and 1000° C., for a time t between 6 and 36 hrs.
1. A crystalline precursor compound for manufacturing a lithium transition metal based oxide powder usable as an active positive electrode material in lithium-ion batteries, the precursor having a general formula Li 1−a ((Ni z (Ni 1/2 Mn 1/2 ) y Co x ) 1−k A k ) 1+a O 2 , wherein x+y+z=1, 0.1≤x≤0.4, 0.40≤z≤0.55, A is a dopant, 0≤k≤0.1, and 0.10≤a≤0.25, wherein the precursor has a crystalline size L expressed in nm, with 77−(67*z)≤L≤97−(67*z).
2. The crystalline precursor compound of claim 1 , having a Li 2 CO 3 content <0.3 wt %.
3. The crystalline precursor compound of claim 1 , having a general formula Li 1−a ((Ni 0.4 (Ni 1/2 Mn 1/2 ) 0.4 Co 0.2 ) 1+a O 2 , with 0.10≤a≤0.20 and 55≤L≤65.
4. The crystalline precursor compound of claim 1 , having a general formula Li 1−a ((Ni 0.55 (Ni 1/2 Mn 1/2 ) 0.3 Co 0.15 ) 1+a O 2 , with 0.15≤a≤0.25 and 45≤L≤55.
5. A positive electrode material having a general formula Li 1+a′ ((Ni z (Ni 1/2 Mn 1/2 ) y Co x ) 1−k A k ) 1−a′ O 2 , wherein x+y+z=1, 0.1≤x≤0.4, 0.25≤z≤0.55, A is a dopant, 0≤k≤0.1, and 0.01≤a′≤0.10, wherein the positive electrode material is prepared from the precursor compound of claim 1 , and wherein the positive electrode material has a ratio I003/I104 value greater than that of the precursor compound and an R value less than that of the precursor compound.
6. A method for preparing a positive electrode material having a general formula Li 1+a′ M 1−a′ O 2 , with M=(Ni z (Ni 1/2 Mn 1/2 ) y Co x ) 1−k A k , wherein x+y+z=1, 0.1≤x≤0.4, 0.30≤z≤0.55, A is a dopant, 0≤k≤0.1, and 0.01≤a′≤0.10, comprising:
providing a M-based precursor prepared from co-precipitation of metal sulphates with a base;
mixing the M-based precursor with Li 2 CO 3 , thereby obtaining a first mixture, whereby the Li to transition metal ratio in the first mixture is between 0.50 and 0.90,
sintering the first mixture in an oxidizing atmosphere at a temperature between 860 and 930° C., for a time between 8 and 36 hrs, thereby obtaining a lithium deficient precursor powder,
mixing the lithium deficient precursor powder with either one of LiOH and LiOH.H 2 O, thereby obtaining a second mixture,
sintering the second mixture in an oxidizing atmosphere at a temperature between 800 and 1000° C., for a time between 6 and 36 hrs.
7. The method according to claim 6 , wherein the lithium deficient precursor powder comprises a crystalline precursor compound having a general formula Li 1−a ((Ni z (Ni 1/2 Mn 1/2 ) y Co x ) 1−k A k ) 1+a O 2 , wherein x+y+z=1, 0.1≤x≤0.4, 0.30≤z≤0.55, A is a dopant, 0≤k≤0.1, and 0.05≤a≤0.50, wherein the precursor has a crystalline size L expressed in nm, with 77−(67*z)≤L≤97−(67*z).
8. The method according to claim 6 , wherein a Li to transition metal ratio in the first mixture is between 0.65 and 0.82.
9. The method according to claim 6 , wherein 0.40≤z≤0.55, and a Li to transition metal ratio in the first mixture is ((2−z)/1.88)±0.05.
10. The method according to claim 9 , wherein the first mixture is sintered at a temperature between 880 and 920° C.
11. The method according to claim 9 , wherein the second mixture is sintered at a temperature between 820 and 860° C., for a time between 8 and 12 hrs.