Positive electrode material and battery using the same

Abstract

The invention provides a positive electrode material and a battery using the same which can achieve a higher discharge voltage and which can obtain excellent charge-and-discharge properties, without reducing the capacity. A positive electrode (12) and a negative electrode (14) are configured through a separator (15) in between. The positive electrode (12) contains a compound expressed by a general formula li_1+xMn_yFe_zPO₄ (wherein x, y and z are values within ranges of 0<x<0.1, 0.5<y<0.95, and 0.9<y+z≦1, respectively). According to the compound, the higher discharge voltage can be obtained due to Mn, the Jahn Teller effect of Mn³⁺ can be attenuated and furthermore distortion of the crystal structure and the reduction of the capacity can be inhibited due to Fe and the excess li.

Description

(wherein x, y and z are values within ranges of 0<x<0.1, 0.5<y<0.95, and 0.9<y+z≦1, respectively.)

TABLE 1
	Compounding Ratio (mol ratio)
	MnCo3:FeC2O.2H2O:NH4H2PO4:Li2CO3	Li1+xMnyFezPO4
Example	1.4:0.54:2:1.03	Li1.03Mn0.7Fe0.27PO4
1
Example	1.4:0.5:2:1.05	Li1.05Mn0.7Fe0.25PO4
2
Example	1.5:0.44:2:1.03	Li1.03Mn0.75Fe0.22PO4
3
Example	1.5:0.4:2:1.05	Li1.05Mn0.75Fe0.2PO4
4
Example	1.5:0.5:2:1.03	Li1.03Mn0.75Fe0.25PO4
5
Compar-	1.4:0.6:2:1	LiMn0.7Fe0.3PO4
ative Ex-
ample 1
Compar-	1.5:0.5:2:1	LiMn0.75Fe0.25PO4
ative Ex-
ample 2

TABLE 2
		Average Discharge
	Discharge Capacity	voltage	Energy Density
	(mAh/g)	(v)	(kW/kg)
Example 1	163	3.56	580
Example 3	163	3.59	585
Example 5	166	3.58	594

Claims

1. A positive electrode material containing a compound expressed by a general formula li_1+xMn_yFe_zPO₄ (wherein x, y and z are values within ranges of 0<x<0.1, 0.5<y<0.95, and 0.9<y+z≦1, respectively).

2. A positive electrode material according to claim 1, wherein the compound contains one having a particle diameter of 10 μm or less and the Brunauer-Emmet-Teller specific surface area thereof is 0.5 m²/g or more.

3. A battery comprising an electrolyte as well as a positive electrode and a negative electrode, wherein the positive electrode contains a compound expressed by a general formula li_1+xMn_yFe_zPO₄ (wherein x, y and z are values within ranges of 0<x≦0.1, 0.5<y<0.95, and 0.9<y+z<1, respectively).

4. A battery according to claim 3, wherein the positive electrode comprises furthermore a conductive agent and a binder.

5. A battery according to claim 3, wherein the negative electrode is constituted to contain one, two or more materials selected from the group consisting of lithium metals, lithium alloys, and materials capable of insertion and extraction of lithium.

6. A battery according to claim 5, wherein the materials capable of insertion and extraction of lithium is constituted to contain one, two or more materials selected from the group consisting of carbonaceous materials, metal compounds, silicon, silicon compounds, and conductive polymers.

7. A battery according to claim 3, wherein the electrolyte is constituted to contain one, two or more materials selected from the group consisting of LiPF₆, LiClO₄, LiAsF₆, LiBF₄, LiCF₃SO₃ and LiN(CF₃SO₂)₂.

8. A battery comprising an electrolyte as well as a positive electrode and a negative electrode, wherein the positive electrode contains a compound containing excess lithium and expressed by a general formula li_1+xMn_yFe_zPO₄, with x, y, and z being values within the ranges of 0<x≦0.1, 0.5<y<0.95, and 0.9<y+z<1, respectively,

wherein,

the negative electrode contains at least one material selected from the group consisting of lithium metals, lithium alloys, and a material capable of insertion and extraction of lithium, and

the electrolyte contains at least one material selected from the group consisting of LiPF₆, LiClO₄, LiAsF₆, LiBF₄, LiCF₃SO₃ and LiN(CF₃SO₂)₂.

9. A positive electrode material containing (a) an olivine compound having excess lithium, the olivine compound being expressed by general formula li_1+xMn_yFe_zPO₄, wherein x, y, and z are values within the ranges of 0<x<0.1, 0.5<y<0.95, and 0.9<y+z<1, respectively; and (b) LiCoO₂, LiNiO₂, LiMnO₂, LiMn₂O₄, a lithium sulfide, or a polymeric material.

10. A positive electrode material according to claim 9, wherein the compound contains a particle having a diameter of 10 μm or less and the Brunauer-Emmet-Teller specific surface area thereof is 0.5 m²/g or more.

11. A battery comprising an electrolyte as well as a positive electrode and a negative electrode, wherein the positive electrode contains (a) a compound containing excess lithium and expressed by general formula li_1+xMn_yFe_zPO₄, with x, y, and z being values within the ranges of 0<x≦0.1, 0.5<y<0.95, and 0.9<y+z<1, respectively; and (b) (b) LiCoO₂, LiNiO₂, LiMnO₂, LiMn₂O₄, a lithium sulfide, or a polymeric material.

12. A battery according to claim 11, wherein the positive electrode further comprises a conductive agent and a binder.

13. A battery according to claim 11, wherein the negative electrode contains at least one material selected from the group consisting of lithium metals, lithium alloys, and a material capable of insertion and extraction of lithium.

14. A battery according to claim 13, wherein the material capable of insertion and extraction of lithium contains at least one material selected from the group consisting of carbonaceous materials, metal compounds, silicon, silicon compounds, and conductive polymers.

15. A battery according to claim 11, wherein the electrolyte contains at least one material selected from the group consisting of LiPF₆, LiClO₄, LiAsF₆, LiBF₄, LiCF₃SO₃, and LiN(CF₃SO₂)₂.