Positive-electrode material for lithium secondary-battery, process for producing the same, positive electrode for lithium secondary battery, and lithium secondary battery
A lithium-transition metal compound powder for a positive-electrode material of lithium secondary batteries can include a lithium-transition metal compound that is capable of an insertion and elimination of lithium ions. The particles in the powder contain, in the inner part thereof, a compound that, when analyzed by an SEM-EDX method, has peaks derived from Group-16 elements belonging to the third or later periods of the periodic table and Group-5 to Group-7 elements belonging to the fifth and sixth periods of the periodic table.
1. A lithium-transition metal compound powder, comprising:
a lithium-transition metal compound capable of an insertion and elimination of lithium ions,
wherein an inner part of particles in the powder comprises a compound that, when analyzed by an SEM-EDX method, has a peak derived from a Group-16 element of the third or later periods of the periodic table and an element of the Group-5 to Group-7 elements of the fifth and sixth periods of the periodic table, and
the powder is suitable for a positive-electrode material of a lithium secondary battery, wherein the lithium-transition metal compound is a powder comprising secondary particles that comprise primary particles of two or more compositions, and
an inner part of the secondary particles comprises primary particles of a compound that, when analyzed by an SEM-EDX method, has peaks derived from a Group-16 element of the third or later periods of the periodic table and an element of the Group-5 to Group-7 elements of the fifth and sixth periods of the periodic table,
wherein a molar ratio of sum of S, Se, Te and Po to the a sum of metallic elements other than Li, S, Se, Te, Po, Mo, W, Nb, Ta, and Re in surface parts of the secondary particles is not more than 500 times a molar ratio of a sum of S, Se, Te and Po to a sum of metallic elements other than Li, S, Se, Te, Po, Mo, W, Nb, Ta and Re in an entirety of the secondary particles.
2. The powder of claim 1 ,
wherein a pore distribution curve of the lithium-transition metal compound has a peak at a pore radius of 80 nm or larger but less than 800 nm.
3. A positive electrode comprising:
a binder,
a current collector, and
a positive-electrode active-material layer comprising the powder of claim 1 .
4. A lithium secondary battery, comprising:
a negative electrode capable of occluding and releasing lithium,
a nonaqueous electrolyte comprising a lithium salt, and
the positive electrode of claim 3 ,
wherein the positive electrode is capable of occluding and releasing lithium.
5. The powder of claim 1 , wherein the powder has a lamellar structure or a spinel structure.
6. The powder of claim 5 , wherein the powder has a lamellar structure.
7. The powder of claim 1 , wherein the molar ratio in the surface parts is 1.05 times or more of the molar ratio in the entirety.
8. The powder of claim 1 , wherein the molar ratio in the surface parts is 300 times or less of the molar ratio in the entirety.
9. A lithium-transition metal compound powder, comprising:
a lithium-transition metal compound capable of an insertion and elimination of lithium ions,
wherein an inner part of particles in the powder comprises a compound that, when analyzed by an SEM-EDX method, has a peak derived from a Group-16 element of the third or later periods of the periodic table and an element of the Group-5 to Group-7 elements of the fifth and sixth periods of the periodic table, and
the powder is suitable for a positive-electrode material of a lithium secondary battery, wherein the lithium-transition metal compound is a powder comprising secondary particles that comprise primary particles of two or more compositions, and
an inner part of the secondary particles comprises primary particles of a compound that, when analyzed by an SEM-EDX method, has peaks derived from a Group-16 element of the third or later periods of the periodic table and an element of the Group-5 to Group-7 elements of the fifth and sixth periods of the periodic table,
wherein a molar ratio of a sum of Mo, W, Nb, Ta, and Re to a sum of metallic elements other than Li, S, Se, Te, Po, Mo, W, Nb, Ta, and Re in surface parts of the secondary particles is not less than 1.05 times a molar ratio of a sum of Mo, W, Nb, Ta, and Re to a sum of metallic elements other than Li, S, Se, Te, Po, Mo, W, Nb, Ta, and Re in an entirety of the secondary particles.
10. The powder of claim 9 , wherein the Group-16 element comprises S, Se, or both.
11. The powder of claim 9 , wherein the molar ratio in the surface parts is 200 times or less of the molar ratio in the entirety.
12. The powder of claim 9 , wherein the molar ratio in the surface parts is 1.05 times or more of the molar ratio in the entirety.
13. The powder of claim 9 , wherein the molar ratio in the surface parts is 300 times or less of the molar ratio in the entirety.