Positive active material, lithium ion secondary battery, battery module, battery pack and electric device

Patent metadata

Field	Value
Publication number	US-2023035380-A1
Application number	US-202217935125-A
Country	US
Kind code	A1
Filing date	Sep 25, 2022
Priority date	Jan 21, 2021
Publication date	Feb 2, 2023
Grant date	—

Abstract

A positive active material is provided. In some embodiments, the positive material includes: a substrate and a coating layer coating the substrate, wherein the coating layer includes a fast ion conductor layer and a carbon coating layer, the substrate includes more than one compound of formula (I): LiFe1-aM1aPO4 formula (I), in formula (I), M1 is more than one selected from Cu, Mn, Cr, Zn, Pb, Ca, Co, Ni, Sr, Nb and Ti, and 0≤a≤0.01; the fast ion conductor layer includes a fast ion conductor of a NASICON structure shown in formula (II), Li3-bFe2-bM2b(PO4)3 formula (II), in formula (II), M2 is more than one selected from Ti, Zr, Hf, Ge and Sn with valence of +4, and 0≤b≤1.

First claim

What is claimed is:

1 . A positive active material, comprising:
a substrate and a coating layer, wherein the coating layer coats the substrate, and the coating layer comprises a fast ion conductor layer and a carbon coating layer, the substrate comprises more than one compound as shown in formula (I):
LiFe 1-a M1 a PO 4   formula (I), wherein

in the formula (I), M1 is more than one selected from Cu, Mn, Cr, Zn, Pb, Ca, Co, Ni, Sr, Nb and Ti, and 0≤a≤0.01, the fast ion conductor layer comprises a fast ion conductor of a NASICON structure as shown in formula (II),
Li 3-b Fe 2-b M2 b (PO 4 ) 3   formula (II), wherein

in the formula (II), M2 is more than one selected from Ti, Zr, Hf, Ge and Sn with valence of +4, and 0≤b≤1.

2 . The positive active material according to claim 1 ,
wherein in the positive active material, molar weights of the LiFe 1-a M1 a PO 4 and the Li 3-b Fe 2-b M2 b (PO 4 ) 3 have a ratio of (1-x):x, and 0<x≤0.005.

3 . The positive active material according to claim 1 ,
wherein carbon has a mass percentage content C % of 1%-1.5% in the positive active material; the positive active material has a specific surface area S of 10 m 2 /g-15 m 2 /g; and a ratio of the specific surface area S to the carbon content C % of the positive active material satisfies 9≤S/C≤12.

4 . The positive active material according to claim 1 ,
wherein the positive active material has pH not less than 9.

5 . The positive active material according to claim 1 ,
wherein free lithium is present in the positive active material, and a pH of the positive active material and a mass percentage content N Li+ % of the free lithium satisfy 0.15≤pH-(36N Li+ +8)≤1.1.

6 . The positive active material according to claim 1 ,
wherein the positive active material has a volume average particle size satisfying 1 μm≤Dv50≤2 μm and 0.4 μm≤Dv10≤0.7 μm.

7 . The positive active material according to claim 1 ,
wherein the positive active material has a powder compaction density ρ≥2.5 g/cm 3 .

8 . The positive active material according to claim 1 ,
wherein the positive active material has a powder resistivity R≤11 Ω·cm.

9 . The positive active material according to claim 1 ,
wherein a positive plate fabricated from the positive material has an electrode plate compaction density of 2.5 g/cm 3 .

10 . A lithium ion secondary battery, comprising the positive active material according to claim 1 .

11 . The lithium ion secondary battery according to claim 10 , comprising:
a positive plate, comprising a positive current collector and a positive film layer provided on at least one surface of the positive current collector and containing the positive active material, and when a button cell is formed by the positive plate and a lithium metal plate, in a 0.1 C charging-discharging curve of the button cell, a charging-discharging platform exists within a voltage range of 2.5-2.9V vs Li + .

12 . A battery module, comprising the lithium ion secondary battery according to claim 10 .

13 . A battery pack, comprising more than one of the lithium ion secondary battery according to claim 10 .

14 . An electric device, comprising:
more than one of the lithium ion secondary battery according to claim 10 , wherein the lithium ion secondary battery or the battery module or the battery pack is used as a power source of the electric device or an energy storage unit of the electric device.

Assignees

• Contemporary Amperex Technology Co Ltd

Inventors

• Leng Xue
• Liu Hongyu
• Bie Changfeng
• Liu Na
• Cai Wanqing

Classifications

• Y02E60/10

  Energy storage using batteries · CPC title

• H01M2220/30

  Batteries in portable systems, e.g. mobile phone, laptop · CPC title

• H01M50/109

  of button or coin shape · CPC title

• H01M10/0427

  Button cells · CPC title

• H01M50/204

  Racks, modules or packs for multiple batteries or multiple cells · CPC title