A medical device includes a rechargeable lithium-ion battery for providing power to the medical device. The lithium-ion battery includes a positive electrode including a current collector and a first active material, a negative electrode including a current collector and a second active material, and an auxiliary electrode including a current collector and a third active material. The auxiliary electrode is configured for selective electrical connection to one of the positive electrode and the negative electrode. The first active material, second active material, and third active material are configured to allow doping and undoping of lithium ions. The third active material exhibits charging and discharging capacity below a corrosion potential of the current collector of the negative electrode and above a decomposition potential of the first active material.
An exemplary embodiment relates to a medical device that includes a rechargeable lithium-ion battery for providing power to the medical device. The lithium-ion battery includes a positive electrode including a current collector and a first active material, a negative electrode including a current collector and a second active material, and an auxiliary electrode including a current collector and a third active material. The auxiliary electrode is configured for selective electrical connection to one of the positive electrode and the negative electrode. The first active material, second active material, and third active material are configured to allow doping and undoping of lithium ions. The third active material exhibits charging and discharging capacity below a corrosion potential of the current collector of the negative electrode and above a decomposition potential of the first active material.
The battery 200 includes at least one positive electrode 210, at least one negative electrode 220, and an auxiliary electrode 260 that may be selectively electrically connected or coupled to the negative electrode 220 (e.g., by a switch 270, and according to another exemplary embodiment, according to a diode or other device). The auxiliary electrode 260, while being shown in the headspace of the battery 200, may be provided in other locations as may be desired. Also, it should be noted that one of the positive electrode 210 and negative electrode 220 may be coupled to the case 202 (e.g., as opposed to being electrically isolated from the case) according to other exemplary embodiments. The electrodes may be provided as flat or planar components of the battery 200, may be wound in a spiral or other configuration, or may be provided in a folded configuration. For example, the electrodes may be wrapped around a relatively rectangular mandrel such that they form an oval wound coil for insertion into a relatively prismatic battery case. According to other exemplary embodiments, the battery may be provided as a button cell battery, a thin film solid state battery, or as another lithium-ion battery configuration.
According to an exemplary embodiment, the active material 214 is a material or compound that includes lithium. The lithium included in the active material 214 may be doped and undoped during discharging and charging of the battery, respectively. According to an exemplary embodiment, the active material 214 is lithium cobalt oxide (LiCoO2). According to another exemplary embodiment, the positive active material is of the form LiCoxNi(1-x)O2, with x being between approximately 0.05 and 0.8. According to another exemplary embodiment, the primary active material is of the form LiMxCoyNi(1-x-y)O2, where M is aluminum or titanium, x is between approximately 0.05 and 0.3 and y is between approximately 0.1 and 0.3. According to another exemplary embodiment, the positive active material is LiCoxMnyNizO2 or LiNixCoyAlzO2. According to other exemplary embodiments, the primary active material may include LiMn2O4.
Other lithium titanate materials which may be suitable for use as the active material 224 may include one or more of include the following lithium titanate spinel materials: HxLiy-xTiOxO4, HxLiy-xTiOxO4, Li4MxTi5-xO12, LixTiyO4, LixTiyO4, Li4[Ti1.67Li0.33-yMy]O4, Li2TiO3, Li4Ti4.75V0.25O2, Li4Ti4.75Fe0.25O11.88, and Li4Ti4.5Mn0.5O12, and LiM′M″XO4 (where M′ is a transition metal, M″ is an optional three valent non-transition metal, and X is zirconium, titanium, or a combination of these two, and where M′ is nickel, cobalt, iron, manganese, vanadium, copper, chromium, molybdenum, niobium, or combinations thereof). Note that such lithium titanate spinel materials may be used in any state of lithiation (e.g., Li4+xTi50O12, where 0≦x≦3).
Another advantageous feature of using a lithium titanate material is that it is believed that when used in a negative electrode of a lithium-ion battery, such materials will cycle lithium at a potential plateau of about 1.5V versus a lithium reference electrode. This is substantially higher than graphitic carbon, which is traditionally used in lithium ion batteries, and cycles lithium down to about 0.1V in the fully charged state. As a result, the battery using lithium titanate is believed to be less likely to result in plating of lithium (which occurs at 0V versus a lithium reference) while being charged. Lithium plating is a well-known phenomenon that can lead to loss in performance of lithium ion batteries. Being free from the risk lithium plating, cells with lithium titanate negative electrodes may also be charged at rates that exceed those with carbon negative electrodes. For example, a common upper limit for the rate of charge in lithium ion batteries is about 1 C (meaning that the battery can be fully charged from the discharged state in one hour). Conversely, it has been reported in literature that lithium titanate may be charged at rates up to 10 C (i.e., attaining full charge in 1/10 hour, or six minutes). Being able to recharge a battery more quickly substantially increases the functionality of devices that employ such a battery. A further advantage of the higher potential of the lithium titanate material is that it avoids decomposition of organic solvents (such as propylene carbonate) commonly used in lithium ion batteries. In so doing, it may reduce negative consequences such as formation of gas, cell swelling, reduction of reversible battery capacity, and buildup of resistive films which reduce battery power.
According to an exemplary embodiment in which the auxiliary electrode 260 is to be coupled to the negative electrode 220, the active material 263 must comprise lithium or be lithiated using a source of lithium (e.g., a lithium powder or a lithium patch, etc.) in electrical contact with the auxiliary electrode. According to an exemplary embodiment in which the active material 263 includes lithium, the active material is LiMn2O4. According to various other exemplary embodiments, the active material may be selected from the following materials and combinations thereof: V2O5, V6O13, LiMn2O4 (spinel), LiMxMn(2-x)O4 (spinel) where M is metal (including Li) and x is between approximately 0.05 and 0.4, Li5Ti4O12, LixVO2 (where x is between approximately 0 and 1), V3O8, MoO3, TiS2, WO2, MoO2, and RuO2, as well as their partially or fully lithiated counterparts.
It should be noted that while a variety of materials have been described above as being useful for active material 263, a variety of additional materials may be utilized in addition to or in place of such materials. For example, the active material 263 may comprise an oxide material such as one or more of LixMoO3 (0<x≦2), LixMoO2 (0<x≦1), LixMo2O4 (0<x≦2), LixMnO2 (0<x≦1), LixMn2O4 (0<x≦2), LixV2O5 (0<x≦2.5), LixV3O8 (0<x≦3.5), LixV6O13 (0<x≦6 for LixVO2.19 and 0<x≦3.6 for LixVO2.17), LixVO2 (0<x≦1), LixWO3 (0<x≦1), LixWO2 (0<x≦1), LixTiO2 (anatase) (0<x≦1), LixTi2O4 (0<x≦2), LixRuO2 (0<x≦1), LixFe2O3 (0<x≦2), LixFe3O4 (0<x≦2), LixCr2O (0<x≦3), LixCr (0<x≦3.8), and LixNiyCo1-yO2 (0<x≦1, 0.90<y≦1.00).
According to another exemplary embodiment shown in FIG. 8, an implantable neurological stimulation device 500 (an implantable neuro stimulator or INS) may include a battery 502 such as those described above with respect to the various exemplary embodiments. Examples of other neuro stimulation products and related components are shown and described in a brochure titled "Implantable Neurostimulation Systems" available from Medtronic, Inc.
3. The medical device of claim 2, wherein a portion of the medical device including the lithium-ion battery is implanted into the body of the patient, wherein the lithium-ion battery may be charged without removing the battery from the body of the patient.
8. The medical device of claim 7, wherein the device is an implantable cardiac defibrillator for, providing a therapeutic high voltage treatment to a patient.
9. The medical device of claim 1, wherein the auxiliary electrode is provided such that it is electrically isolated from the positive electrode and the negative electrode within the battery.
10. The medical device of claim 9, wherein the auxiliary electrode is configured to be selectively electrically connected to and disconnected from one of the positive electrode and the negative electrode using a mechanism provided external to the battery.
11. The medical device of claim 1, wherein the auxiliary electrode is configured to be selectively electrically connected to and disconnected from one of the positive electrode and the negative electrode using a diode.
12. The medical device of claim 11, wherein the battery is configured to electrically connect the auxiliary electrode to the negative electrode when the potential of the negative electrode exceeds the potential of the auxiliary electrode by a predetermined value.
13. The medical device of claim 11, wherein the battery is configured to electrically connect the auxiliary electrode to the positive electrode when the potential of the positive electrode falls below the potential of the auxiliary electrode by a predetermined value.
14. The medical device of claim 1, wherein the auxiliary electrode is configured to be selectively electrically connected to and disconnected from one of the positive electrode and the negative electrode using a switch.
15. The medical device of claim 14, wherein the switch is configured to selectively electrically connect the auxiliary electrode when the difference in voltage between the positive electrode and the negative electrode falls below a predetermined value.
16. The medical device of claim 14, wherein the switch is configured to selectively electrically disconnect the auxiliary electrode when the difference in voltage between the positive electrode and the negative electrode exceeds a predetermined value.
17. The medical device of claim 1, wherein the auxiliary electrode is configured for selective electrical coupling to the negative electrode.
18. The medical device of claim 17, further comprising a source of lithium in electrical contact with the auxiliary electrode.
19. The medical device of claim 18, wherein the source of lithium comprises at least one of a lithium patch and powdered lithium.
20. The medical device of claim 17, wherein the third active material comprises electrochemically active lithium.
21. The medical device of claim 20, wherein the third active material comprises a material selected from the group consisting of LiMn2O4, LixVO2, LiMxMn(2-x)O4 (where M is a metal), and combinations thereof.
22. The medical device of claim 1, wherein the auxiliary electrode is configured for selective electrical connection to the positive electrode.
23. The medical device of claim 22, wherein the third active material does not include electrochemically active lithium.
24. The medical device of claim 23, wherein second active material comprises a lithium titanate material.
25. The medical device of claim 23, further comprising a source of lithium in electrical contact with the negative electrode.
26. The medical device of claim 25, wherein the source of lithium comprises at least one of a lithium patch and powdered lithium.
27. The medical device of claim 26, wherein the source of lithium is configured to provide a lithium capacity for the negative electrode sufficient to at least compensate for irreversible loss of capacity of the negative electrode.
28. The medical device of claim 23, wherein the third active material comprises a material selected from the group consisting of V2O5, V6O13, V3O8, MoO3, TiS2, WO2, MoO2, RuO2, and combinations thereof.
29. The medical device of claim 1, wherein the first active material comprises a material selected from the group consisting of LiCoO2, a material having the form LiCoxNi(1-x)O2, a material having the form LiCoxMnyNixO2, and a material having the form LiNixCoyAlxO2.
30. The medical device of claim 1, further comprising a polymeric separator provided intermediate the positive electrode and the negative electrode.
31. The medical device of claim 1, wherein the battery has a capacity between approximately 10 mAh and 1000 mAh.
wherein the third electrode is configured for selective electrical coupling to and decoupling from the second electrode.
33. The device of claim 32, wherein the third active material exhibits charge and discharge capacity below a corrosion potential of the second current collector and any other battery component in electrical contact with the second current collector.
34. The device of claim 32, wherein at least a portion of the device is configured for implantation into a body of a patient and the lithium-ion battery may be charged without removing the battery from the body of the patient.
35. The device of claim 32, wherein the device comprises a neurological stimulation device.
36. The device of claim 32, wherein the device is selected from the group consisting of a cardiac defibrillator, a cardiac pacemaker, a cardiac contractility modulator, a cardioverter, a drug administration device, a cochlear implant, a hearing aid, a sensor, a telemetry device, and a diagnostic recorder.
37. The device of claim 36, wherein the device is an implantable cardiac defibrillator for providing a therapeutic high voltage treatment to a patient.
38. The device of claim 32, wherein the third active material exhibits charge and discharge capacity below a corrosion potential of the second current collector.
39. The device of claim 32, wherein the third electrode is provided such that it is electrically isolated from the first electrode and the second electrode within the battery.
40. The device of claim 32, wherein the first electrode is a positive electrode and the second electrode is a negative electrode.
41. The device of claim 40, further comprising a source of lithium in electrical contact with the auxiliary electrode.
42. The device of claim 41, wherein the source of lithium comprises at least one of a lithium patch and powdered lithium.
43. The device of claim 41, wherein the third active material comprises electrochemically active lithium.
44. The device of claim 43, wherein the third active material comprises a material selected from the group consisting of LiMn2O4, LixVO2, LiMxMn(2-x)O4 (where M is a metal), and combinations thereof.
45. The device of claim 32, wherein the first electrode is a negative electrode and the second electrode is a positive electrode.
46. The device of claim 32, wherein the first active material comprises lithium.
47. The device of claim 46, wherein first active material comprises a lithium titanate material.
48. The device of claim 45, further comprising a source of lithium provided in electrical contact with the first electrode.
49. The device of claim 48, wherein the source of lithium comprises at least one of a lithium patch and powdered lithium.
50. The device of claim 49, wherein the source of lithium is configured to provide a lithium capacity for the first electrode sufficient to at least compensate for irreversible loss of capacity of the first electrode.
51. The device of claim 44, wherein the third active material comprises a material selected from the group consisting of V2O5, V6O13, V3O8, MoO3, TiS2, WO2, MoO2, RuO2, and combinations thereof.
52. The device of claim 32, wherein the second active material comprises a material selected from the group consisting of LiCoO2, a material having the form LiCoxNi(1-x)O2, a material having the form LiCoxMnyNizO2, and a material having the form LiNixCoyAlzO2.
53. The device of claim 32, wherein the third electrode is configured to be selectively electrically connected and disconnected to one of the first electrode and the second electrode using a mechanism provided external to the battery.
54. The device of claim 53, wherein the mechanism is selected from a switch and a diode.
55. The device of claim 54, wherein the mechanism is a switch and the switch is configured to electrically connect the third electrode to the second electrode when a voltage difference between the first electrode and the second electrode falls below a predetermined value.
56. The device of claim 54, wherein the mechanism is a switch and the switch is configured to electrically disconnect the third electrode from the second electrode when a voltage difference between the first electrode and the second electrode exceeds a predetermined value.
57. The device of claim 54, wherein the mechanism is a diode and the diode is configured to electrically connect the third electrode to the second electrode when the potential of the third electrode exceeds the potential of the second electrode by a predetermined value.
58. The device of claim 54, wherein the mechanism is a diode and the diode is configured to electrically connect the third electrode to the first electrode when the potential of the third electrode falls below the potential of the first electrode by a predetermined value.
59. The device of claim 32, wherein the lithium-ion battery has a capacity between approximately 10 mAh and 1000 mAh.
an auxiliary electrode having a current collector and an auxiliary active material provided on at least one side of the current collector of the auxiliary electrode, the auxiliary electrode configured to be selectively coupled to the negative electrode when a predetermined condition is present.
61. The system of claim 60, wherein at least a portion of the medical device is configured for implantation into a body of a patient.
62. The system of claim 61, wherein the lithium-ion battery may be charged without removing the battery from the body of the patient.
63. The system of claim 60, wherein the system comprises a neurological stimulation device.
64. The system of claim 60, wherein the system comprises a device selected from the group consisting of a cardiac defibrillator, a cardiac pacemaker, a cardiac contractility modulator, a cardioverter, a drug administration device, a cochlear implant, a hearing aid, a sensor, a telemetry device, and a diagnostic recorder.
65. The system of claim 60, wherein the active material provided on the positive current collector comprises a material selected from the group consisting of LiCoO2, a material having the form LiCoxNi(1-x)O2, a material having the form LiCoxMnyNizO2, and a material having the form LiNixCoyAlzO2.
66. The system of claim 60, wherein the auxiliary active material comprises lithium and provides charging and discharging capacity for the positive electrode below a corrosion potential of the negative current collector and above a decomposition potential of the primary active material provided on the positive current collector.
67. The system of claim 66, wherein the auxiliary active material comprises a material selected from the group consisting of LiMn2O4, LixVO2, LiMxMn(2-x)O4 (where M is a metal), and combinations thereof.
68. The system of claim 67, further comprising a source of lithium in electrical contact with the auxiliary electrode.
69. The system of claim 68, wherein the source of lithium comprises at least one of a lithium patch and powdered lithium.
70. The system of claim 60, wherein the auxiliary electrode is provided such that it is electrically isolated from the positive electrode and the negative electrode within the battery.
71. The system of claim 60, wherein the auxiliary electrode is configured to be selectively electrically connected to and disconnected from the negative electrode using a mechanism provided external to the battery.
72. The system of claim 71, wherein the mechanism is selected from a switch and a diode.
73. The system of claim 72, wherein the mechanism is a switch and the switch is configured to electrically connect the auxiliary electrode to the negative electrode when a voltage difference between the positive electrode and the negative electrode falls below a predetermined value.
74. The system of claim 72, wherein the mechanism is a switch and the switch is configured to electrically disconnect the auxiliary electrode from the negative electrode when a voltage difference between the positive electrode and the negative electrode falls exceeds a predetermined value.
75. The system of claim 72, wherein the mechanism is a diode and the diode is configured to electrically connect the auxiliary electrode to the negative electrode when the potential of the negative electrode exceeds the potential of the auxiliary electrode by a predetermined value.
76. The system of claim 72, wherein the mechanism is a diode and the diode is configured to electrically connect the auxiliary electrode to the positive electrode when the potential of the positive electrode falls below the potential of the auxiliary electrode by a predetermined value.
77. The system of claim 60, wherein the positive electrode and the negative electrode have a zero voltage crossing potential below the corrosion potential of the negative current collector and above the decomposition potential of the active material provided on the positive current collector.
78. The system of claim 60, wherein the negative current collector comprises copper.
79. The system of claim 60, wherein the negative current collector comprises titanium.
80. The system of claim 60, wherein the lithium-ion battery has a capacity between approximately 10 mAh and 1000 mAh.
82. The method of claim 81, further comprising electrically connecting the auxiliary electrode to the negative electrode when a predetermined condition is met.
83. The method of claim 82, wherein the predetermined condition comprises the potential of the negative electrode exceeding the potential of the auxiliary electrode by a predetermined value.
84. The method of claim 82, wherein the predetermined condition comprises a difference between the voltage of the negative electrode and the positive electrode falling below a predetermined value.
85. The method of claim 81, wherein the step of electrically connecting the auxiliary electrode to the negative electrode comprises connecting the auxiliary electrode to the negative electrode using a diode.
86. The method of claim 81, wherein the step of electrically connecting the auxiliary electrode to the negative electrode comprises connecting the auxiliary electrode to the negative electrode using a switch.
87. The method of claim 86, the step of electrically connecting the auxiliary electrode to the negative electrode further comprises using a control circuit to send a signal to the switch.
88. The method of claim 81, further comprising electrically disconnecting the auxiliary electrode from the negative electrode when a predetermined condition is met.
89. The method of claim 81, wherein the step of providing at least a portion of a medical device in contact with the patient comprises implanting at least a portion of the medical device in the patient.
90. The method of claim 89, further comprising charging the battery without removing the implanted portion of the medical device from the patient.
91. The method of claim 81, wherein the medical device comprises a neurological stimulation device.
92. The method of claim 81, wherein the step of providing a treatment to the patient comprises electrically stimulating a portion of at least one of a patient's brain and a patient's spine.
93. The method of claim 81, wherein the step of providing a treatment to the patient comprises selectively providing a plurality of therapeutic treatments to a patient.
94. The method of claim 81, wherein the medical device is selected from the group consisting of a cardiac defibrillator, a cardiac pacemaker, a cardiac contractility modulator, a cardioverter, a drug administration device, a cochlear implant, a hearing aid, a sensor, a telemetry device, and a diagnostic recorder.
95. The method of claim 94, wherein the medical device is an implantable cardiac defibrillator for providing a therapeutic high voltage treatment to a patient.
96. The method of claim 81, wherein the battery has a capacity between approximately 10 mAh and 1000 mAh.