High capacity, dimensionally stable anode from low-bulk density amorphous silicon for lithium-ion batteries

Patent metadata

Field	Value
Publication number	US-9627684-B2
Application number	US-201414180571-A
Country	US
Kind code	B2
Filing date	Feb 14, 2014
Priority date	Feb 14, 2014
Publication date	Apr 18, 2017
Grant date	Apr 18, 2017

Abstract

An anode active material for a lithium-ion battery cell comprises low density silicon. The anode active material is provided in an anode for a lithium-ion battery. Also disclosed are methods of making the anode active material.

First claim

What is claimed is:

1. An anode for a lithium-ion battery comprising a substrate and an anode active material, wherein the anode active material comprises amorphous silicon, in an unpressed state, having a bulk density of between 0.06 g/cm 3 and 0.10 g/cm 3 , wherein the amorphous silicon has an inter-particle porosity of between 60% and 80%.

2. The anode of claim 1 having an active material loading on the substrate of less than or equal to 3.0 mg/cm 2 .

3. The anode of claim 1 , wherein a thickness of the anode active material in a fully-lithiated state has an expanded thickness of less than 200% of a thickness of the anode active material in a pre-lithiated state.

4. The anode of claim 1 , wherein a thickness of the anode active material in a fully-lithiated state has an expanded thickness of less than 100% of a thickness of the anode active material in a pre-lithiated state.

5. The anode of claim 1 , wherein a thickness of the anode active material in a fully-lithiated state has a thickness that is substantially equal to a thickness of the anode active material in a pre-lithiated state.

6. A lithium-ion battery having a plurality of unit cells, each unit cell comprising:
an anode comprising an anode active material of amorphous silicon, in an unpressed state, having a bulk density of between 0.06 g/cm 3 and 0.10 g/cm 3 , wherein the amorphous silicon has an inter-particle porosity of between 60% and 80%;
a cathode comprising a cathode active material comprising lithium; and
an electrolyte there between.

7. The lithium-ion battery of claim 6 , wherein a thickness of the anode active material in a fully-lithiated state has an expanded thickness of less than 100% of a thickness of the anode active material in a pre-lithiated state.

8. The lithium-ion battery of claim 6 , wherein a thickness of the anode active material in a fully-lithiated state has a thickness that is substantially equal to a thickness of the anode active material in a pre-lithiated state.

9. A method of preparing an anode for a lithium-ion battery comprising: preparing a solution of low density silicon defined as amorphous silicon having a bulk density of between 0.06 g/cm 3 and 0.10 g/cm 3 and an inter-particle porosity of between 60% and 80%, a conductive material and a binder; coating an electrode substrate with the solution to form the anode; pre-drying the anode without pressing the anode to preserve the inter-particle porosity; testing an active material loading of the low density silicon in the anode; if the active material loading is within a target loading range, then calcinating and drying the anode without pressing the anode; and if the active material loading is not within the target loading range, then adjusting the active material loading of the solution on the electrode substrate and re-testing.

10. The method of claim 9 , wherein the target loading density range is 2 to 3 mg/cm 2 .

11. The method of claim 9 , wherein the solution is prepared with between 70 and 90 weight percent low density silicon.

Assignees

• Nissan North America Inc

Inventors

• Ramaswamy Nagappan
• Aurora Peter
• Han Taehee

Classifications

• H01M10/052

  Li-accumulators · CPC title

• H01M2004/021

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

• H01M2004/027

  Negative electrodes · CPC title

• H01M4/386 Primary

  Silicon or alloys based on silicon · CPC title

• H01M4/0471

  involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis · CPC title