Apparatus and method for accurate energy device state-of-health (SoH) monitoring

1. A method for testing the state-of-health of an electrochemical energy device, comprising:

applying electrical excitations to the energy device at a predetermined electrical excitation frequency ω e ;

applying mechanical excitations to the energy device at a predetermined mechanical excitation frequency ω m ;

measuring an electrically-induced phase difference Δθ e (ω e ) between voltage (V) and current (I) within the energy device from applying said electrical excitations;

measuring a mechanically-induced phase difference Δθ e (ω m ) between voltage (V) and current (I) within the energy device from applying said mechanical excitations; and

deducing the state-of-health of said energy device by comparing said electrically-induced phase difference Δθ e (ω e ) with said mechanically-induced phase difference Δθ e (ω m ).

2. The method of claim 1 , further comprising:

taking a difference Δθ=Δθ e (ω e )−Δθ e (ω m ) between said electrically-induced phase difference Δθ e and said mechanically-induced phase difference Δθ e (ω m ); and

using said difference as a basis to deduce said SoH.

3. The method of claim 2 , further comprising:

deducing the state-of-health of said energy device by determining a magnitude of Δθ=Δθ e (ω e )−Δθ e (ω m ) in relation to 0°, wherein better state-of-health is deduced from said magnitudes being larger and poorer state-of-health is deduced from said magnitudes being smaller.

4. The method of claim 2 , further comprising:

deducing that said energy device is approaching its end of life by determining that Δθ=Δθ e (ω e )−Δθ e (ω m )→0°.

5. The method of claim 1 , further comprising:

at a baseline time, determining baseline-time phase differences Δθ e (ω e ) and Δθ e (θ m ) between current and voltage of said energy device;

at a later time, determining later-time phase differences Δθ e (ω e ) and Δθ e (θ m ) between current and voltage of said energy device; and

deducing said state of health by comparing said later-time phase difference with said baseline-time phase difference.

6. The method of claim 5 , further comprising:

deducing said state of health by determining how much said later-time phase difference has diminished from said baseline time phase difference.

7. The method of claim 6 , further comprising deducing a magnitude of decline in said state of health substantially in proportion to said diminution.

8. The method of claim 1 , wherein:

a difference between measurements of internal impedance Z INT the energy device when said electrical excitation frequency ω e is applied versus when said mechanical excitation frequency ω m is applied, is determined according to:

Z

INT

e

⁡

(

ω

e

)

-

Z

INT

e

⁡

(

ω

m

)

=

(

1

R

el

⁡

(

ω

e

)

1

R

el

2

⁡

(

ω

e

)

+

(

ω

e

⁢

C

b

⁡

(

ω

e

)

)

2

-

1

R

el

⁡

(

ω

m

)

1

R

el

2

⁡

(

ω

m

)

+

(

ω

e

⁢

C

b

⁡

(

ω

m

)

)

2

)

-

j

(

ω

e

⁢

C

b

⁡

(

ω

e

)

1

R

el

2

⁡

(

ω

e

)

+

(

ω

e

⁢

C

b

⁡

(

ω

e

)

)

2

-

ω

e

⁢

C

b

⁡

(

ω

m

)

1

R

el

2

⁡

(

ω

m

)

+

(

ω

e

⁢

C

b

⁡

(

ω

m

)

)

2

)

,

where R el designates an electrochemical resistance of said energy device and C b designates a storage capacity of said 7 energy device; further comprising:

deducing said electrically-induced phase difference Δθ e (θ e ) between said voltage V and said current I according to

Z

INT

e

⁡

(

ω

e

)

=

V

⁢

√

θ

e

⁡

(

ω

e

)

I

;

and

deducing said mechanically-induced phase difference Δθ e (ω m ) between said voltage V and said current I according to

Z

INT

e

⁡

(

ω

m

)

=

V

⁢

√

θ

e

⁡

(

ω

m

)

I

.

9. A apparatus for testing the state-of-health of an electrochemical energy device, comprising:

an electrical excitation source for applying electrical excitations to the energy device at a predetermined electrical excitation frequency ω e ;

a mechanical excitation source for applying mechanical excitations to the energy device at a predetermined mechanical excitation frequency ω m ;

a measurement device for measuring an electrically-induced phase difference Δθ e (ω m ) between voltage (V) and current (I) within the energy device from applying said electrical excitations; and

said measurement device for further measuring a mechanically-induced phase difference Δθ e (ω m ) between voltage (V) and current (I) within the energy device from applying said mechanical excitations; wherein

the state-of-health of said energy device is deduced by comparing said electrically-induced phase difference Δθ e (ω e ) with said mechanically-induced phase difference Δθ e (ω m ).

10. The apparatus of claim 9 , wherein:

the state-of-health of said energy device is deduced by taking a difference Δθ=Δθ e (ω e )−Δθ e (ω m ) between said electrically-induced phase difference Δθ e and said mechanically-induced phase difference Δθ e (ω m ).

11. The apparatus of claim 10 , wherein:

the state-of-health of said energy device is deduced by determining a magnitude of Δθ=Δθ e (ω e )−Δ e (ω m ) in relation to 0°, and wherein better state-of-health is deduced from said magnitudes being larger and poorer state-of-health is deduced from said magnitudes being smaller.

12. The apparatus of claim 10 , wherein:

said energy device is approaching its end of life is deduced by determining that Δθ=Δθ e (ω e )−Δθ e (ω m )→0°.

13. The apparatus of claim 9 , wherein:

baseline-time phase differences Δθ e (ω e ) and Δθ e (ω m ) between current and voltage of said energy device are determined at a baseline time;

later-time phase differences Δθ e (ω e ) and Δθ e (ω m ) between current and voltage of said energy device are determined at a later time;

said baseline-time phase difference is compared with said later-time phase difference to deduce said state-of-health.

14. The apparatus of claim 13 , wherein:

said state of health is deduced by determining how much said later-time phase difference has diminished from said baseline time phase difference.

15. The apparatus of claim 14 , wherein a magnitude of decline in said state of health is deduced substantially in proportion to said diminution.

16. The apparatus of claim 9 , wherein:

a difference between measurements by said measurement device of internal impedance Z INT the energy device when said electrical excitation frequency ω e is applied versus when said mechanical excitation frequency ω m is applied, is determined according to:

Z

INT

e

⁡

(

ω

e

)

-

Z

INT

e

⁡

(

ω

m

)

=

(

1

R

el

⁡

(

ω

e

)

1

R

el

2

⁡

(

ω

e

)

+

(

ω

e

⁢

C

b

⁡

(

ω

e

)

)

2

-

1

R

el

⁡

(

ω

m

)

1

R

el

2

⁡

(

ω

m

)

+

(

ω

e

⁢

C

b

⁡

(

ω

m

)

)

2

)

-

j

(

ω

e

⁢

C

b

⁡

(

ω

e

)

1

R

el

2

⁡

(

ω

e

)

+

(

ω

e

⁢

C

b

⁡

(

ω

e

)

)

2

-

ω

e

⁢

C

b

⁡

(

ω

m

)

1

R

el

2

⁡

(

ω

m

)

+

(

ω

e

⁢

C

b

⁡

(

ω

m

)

)

2

)

,

where R el designates an electrochemical resistance of said energy device and C b designates a storage capacity of said energy device;

said electrically-induced phase difference Δθ e (ω e ) between said voltage V and said current I is deduced according to

Z

INT

e

⁡

(

ω

e

)

=

V

⁢

√

θ

e

⁡

(

ω

e

)

I

;

and

said mechanically-induced phase difference Δθ e (ω m ) between said voltage V and said current I is deduced according to

Z

INT

e

⁡

(

ω

m

)

=

V

⁢

√

θ

e

⁡

(

ω

m

)

I

.