Positive electrode active material of power storage device, power storage device, electrically propelled vehicle, and method for manufacturing power storage device

Patent metadata

Field	Value
Publication number	US-9318741-B2
Application number	US-201113093050-A
Country	US
Kind code	B2
Filing date	Apr 25, 2011
Priority date	Apr 28, 2010
Publication date	Apr 19, 2016
Grant date	Apr 19, 2016

Abstract

An object is to improve the characteristics of a power storage device such as a charging and discharging rate or a charge and discharge capacity. The grain size of particles of a positive electrode active material is nano-sized so that a surface area per unit mass of the active material is increased. Specifically, the grain size is set to greater than or equal to 10 nm and less than or equal to 100 nm, preferably greater than or equal to 20 nm and less than or equal to 60 nm. Alternatively, the surface area per unit mass is set to 10 m 2 /g or more, preferably 20 m 2 /g or more. Further, the crystallinity of the active material is increased by setting an XRD half width to greater than or equal to 0.12° and less than 0.17°, preferably greater than or equal to 0.13° and less than 0.16°.

First claim

What is claimed is:

1. A manufacturing method of a power storage device comprising the step of:
forming a positive electrode comprising the steps of:
performing a first grinding on a mixture of raw materials;
performing a first baking on the mixture after the first grinding;
performing a first pressure treatment before the first baking;
performing a second grinding on the mixture after the first baking;
adding a saccharide to the mixture after the second grinding, so that a surface of the mixture is supported by a carbon material;
performing a second baking on the mixture after the adding at a higher temperature than the first baking, so that a positive electrode active material is formed; and
performing a second pressure treatment before the second baking,

wherein the positive electrode active material has a surface area per unit mass of 24 m 2 /g or more and 27.5 m 2 /g or less, and an X-ray diffraction half width of greater than or equal to 0.13° and less than 0.17°.

2. The manufacturing method of a power storage device according to claim 1 ,
the positive electrode active material is represented by a formula Li (2-x) MSiO 4 ,
x is a value changing within a range 0≦x≦2 due to insertion and extraction of a lithium ion during charging and discharging, and
M is a transition metal element selected from the group consisting of iron, nickel, manganese, and cobalt.

3. The manufacturing method of a power storage device according to claim 2 , the positive electrode active material belongs to a space group selected from the group consisting of space group P 1211 , space group Pmn 21 , space group P 121 /n 1 , and space group Pbn 21 .

4. The manufacturing method of a power storage device according to claim 1 ,
the positive electrode active material is represented by a formula Li (2-x) Fe s Ni u SiO 4 ,
x is a value changing within a range 0≦x≦2 due to insertion and extraction of a lithium ion during charging and discharging, and
s+u=1, 0≦s≦1, and 0≦u≦1.

5. The manufacturing method of a power storage device according to claim 1 ,
the positive electrode active material is represented by a formula Li (2-x) Fe s Mn t Ni u SiO 4 ,
x is a value changing within a range 0≦x≦2 due to insertion and extraction of a lithium ion during charging and discharging, and
s+t+u=1, 0≦s≦1, 0≦t≦1, and 0≦u≦1.

6. The manufacturing method of a power storage device according to claim 1 , the saccharide is added at greater than or equal to 1 wt % and less than or equal to 14 wt %.

7. The manufacturing method of a power storage device according to claim 1 comprising the step of forming a negative electrode over the positive electrode with an electrolyte interposed therebetween.

8. The manufacturing method of a power storage device according to claim 1 , the second baking is performed in a nitrogen atmosphere at a baking temperature of higher than or equal to 550° C. and lower than or equal to 700° C.

9. The manufacturing method of a power storage device according to claim 1 , the positive electrode active material is lithium iron phosphate.

10. The manufacturing method of a power storage device according to claim 1 , comprising the step of:
forming a negative electrode comprising the steps of:
forming an amorphous silicon layer over a negative electrode collector, the amorphous silicon layer having a thickness of 100 nm and less than or equal to 5 μm;
adding nickel to the amorphous silicon layer; and
performing a heat treatment to the amorphous silicon layer so that the amorphous silicon layer is crystallized.

11. The manufacturing method of a power storage device according to claim 10 , comprising the step of forming an oxide layer on a surface of the amorphous silicon layer before the adding step.

Assignees

• Kawakami Takahiro
• Yamakaji Masaki
• Semiconductor Energy Lab

Inventors

• Kawakami Takahiro
• Yamakaji Masaki

Classifications

• B60L50/64

  Constructional details of batteries specially adapted for electric vehicles · CPC title

• H01M2004/021

  Physical characteristics, e.g. porosity, surface area · CPC title

• H01M4/1397

  of electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy · CPC title

• H01M4/136

  Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title