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

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.