Lithium ion battery capable of being discharged to zero volts
A lithium ion battery particularly configured to be able to discharge to a very low voltage, e.g. zero volts, without causing permanent damage to the battery. More particularly, the battery is configured to define a Zero Volt Crossing Potential (ZCP) which is lower than a Damage Potential Threshold (DPT).
1. A method of manufacturing a battery, comprising:
providing a positive electrode and a negative electrode, said positive electrode comprising a metal substrate having a first active material comprising lithium formed thereon and said negative electrode comprising a metal substrate having a second active material comprising carbon formed thereon, wherein said positive and negative electrodes define a Zero Volt Crossing Potential (ZCP) relative to a reference level when the voltage between said electrodes is zero;
providing an electrolyte wherein said negative electrode can react with said electrolyte to form a solid electrolyte interface (SEI) layer, said SEI layer being susceptible of damage when a voltage potential exceeding a Film Dissolution Potential (FDP) is applied thereto, and wherein said FDP is lower than the maximum positive operating potential of the battery; wherein
said positive and negative electrodes are selected to establish ZCP at a lower level than FDP to prevent dissolution of said SEI layer during storage at a predetermined temperature.
2. The method of claim 1 , wherein said negative electrode substrate is susceptible of permanent damage when a potential exceeding a Substrate Dissolution Potential (SDP) is applied thereto; and wherein
said positive and negative electrodes are selected and configured to establish ZCP at a lower level than SDP in order to prevent dissolution of the negative substrate during storage at said predetermined temperature.
3. The method of claim 1 , wherein said negative electrode substrate is formed of a material selected from the group consisting of titanium and titanium alloy.
4. The method of claim 1 , wherein said negative electrode substrate is formed of stainless steel.
5. The method of claim 1 , wherein said negative electrode substrate is formed of a material selected from the group consisting of nickel and nickel alloy.
6. The method of claim 1 , wherein said positive electrode active material comprises cobalt.
7. The method of claim 6 , wherein said positive electrode active material further comprises nickel.
8. The method of claim 1 , wherein said positive electrode active material consists of an oxide.
9. The method of claim 8 , wherein said oxide comprises lithium, nickel, and cobalt.
10. The method of claim 1 , wherein said negative electrode active material consists of carbon.
11. The method of claim 1 , wherein said electrolyte consists of a liquid electrolyte.
12. The method of claim 11 , wherein said liquid electrolyte comprises a lithium salt dissolved in EC:DEC.
13. The method of claim 12 , wherein said lithium salt is LiPF 6 .
14. The method of claim 1 , wherein said predetermined temperature is body temperature.
15. The method of claim 1 , wherein said predetermined temperature is 37° C.
16. The method of claim 1 , wherein said predetermined temperature is 25° C.
17. The method of claim 1 , further comprising providing a battery management circuit that attempts to stop battery discharge when the battery voltage reaches 2.5 V.
18. The method of claim 1 , wherein said ZCP is greater than about 3 V vs. Li/Li + .
19. The method of claim 1 , wherein said positive electrode has a positive discharge curve having a negative slope over most of said positive discharge curve, wherein said negative slope is more negative than the negative slope over most of the discharge curve of LiCoO 2 .
20. The method of claim 1 , further comprising the step of:
housing said positive and negative electrodes in a case, wherein said case is configured for implanting in a patient's body.
21. The method of claim 20 , further comprising the step of:
hermetically sealing the case.
22. The method of claim 20 , wherein said case has a volume of less than 30 cc.
23. A method for making a rechargeable lithium ion battery comprising:
providing a positive electrode comprising a metal substrate having a first active material comprising lithium formed thereon;
providing a negative electrode comprising a substrate selected from the group consisting of titanium and titanium alloy having a second active material comprising carbon formed thereon;
said negative electrode being susceptible of damage when a voltage exceeding a Damage Potential Threshold (DPT) is applied thereto, and wherein said DPT is lower than the maximum positive operating potential of the battery;
said positive and negative electrodes defining a Zero Volt Crossing Potential (ZCP) relative to a reference level when the voltage between said electrodes is zero; and wherein
said positive and negative electrodes are selected and configured to define a value of ZCP which is less than the value of DPT at a predetermined temperature.
24. The method of claim 23 , wherein the first active material comprises cobalt.
25. The method of claim 24 , wherein the first active material further comprises nickel.