Patent Application
20200395593
The present description relates generally to strategies for anode pre-lithiation for use in lithium ion batteries.
Lithium (Li) ion batteries are and have been widely used in a number of different applications, including, but not limited to, consumer electronics, uninterruptible power supplies, transportation, and stationary applications. Li ion batteries function by passing Li ions from a positive electrode, or cathode, including positive electrode active materials, to a Li-based negative electrode, or anode, during charging and then passing Li ions back to the cathode from the anode during discharge. A necessary consequence of the charge/discharge process is the formation of a solid-electrolyte interphase (SEI) layer on the anode during the first charge cycle. Specifically, some of the Li from the cathode during the first charge cycle is consumed to form the SEI on the anode surface, leading to high irreversible capacity and low initial columbic efficiency during the first charge cycle.
To counter low efficiency due to anodic SEI formation, a pre-lithiation approach may be employed to offset the lithium loss on the anode surface. Such a pre-lithiation approach may be accomplished in a number of ways, such as use of stabilized lithium metal powder (SLMP), thin Li foil, and electrochemical approaches to pre-lithiate the anode. However, there are potential issues with such approaches. For example, it may be challenging to control a rate to which the anode is pre-lithiated for at least the pre-lithiation strategies that employ the use of SLMP and thin Li foil. Inability to control the rate may lead to inefficient and/or non-uniform anode pre-lithiation, which may thus in turn affect battery parameters including but not limited to first charge capacity, first discharge capacity, initial coulombic efficiency, and capacity retention. Electrochemical pre-lithiation methodology is an approach which could control the rate but its efficiency of pre-lithiation fluctuates with different cell design chemistry. The efficiency of pre-lithiation with electrochemical method could be low even though the voltage of pre-lithiation step may be well controlled. Similar to that discussed above, non-optimal anode pre-lithiation may lead to degraded battery parameters related to charge/discharge capacity, coulombic efficiency, and capacity retention.
The inventors have identified the above-mentioned issues and have herein developed solutions to at least partially address these issues. In one example, a method for improving a capacity of a lithium ion battery may include providing a three-electrode system that includes a cathode, an anode, and an auxiliary electrode. As described, the method includes determining an anode loading amount and loading the anode to the determined anode loading amount, and pre-lithiating the anode with lithium from the auxiliary electrode, where a pre-lithiation efficiency is based on the anode loading amount. For example, the method may include controlling the anode loading amount in order to increase pre-lithiation of the anode.
As examples, the auxiliary electrode may be a lithium metal electrode, a lithium iron phosphate electrode, a NiCoMn electrode or a NiCoAl electrode. The anode may include graphite, silicon/graphite, silicon oxide/graphite, silicon or silicon oxide (SiOx), etc.
In one example, a rate and or a degree to which the anode is pre-lithiated may be controlled. Controlling the rate may include adjusting a current density that is used for pre-lithiating the anode. Controlling the degree to which the anode is pre-lithiated may include controlling a duration whereby the anode is pre-lithiated.
Such a method may in some examples improve the capacity of the lithium battery such that an initial coulombic efficiency is approximately 90%. Additionally or alternatively, such a method may in some examples improve the capacity of the lithium ion battery such that a first discharge capacity under 0.1C is greater than 83 ampere hours. Additionally or alternatively, such a method may in some examples improve the capacity of the lithium ion battery such that a second discharge capacity under 0.3C is greater than 83 ampere hours.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.
The following description relates to systems and methods for anode pre-lithiation strategies. Examples of pre-lithiation strategies are discussed in terms of both small pouch cells and large format pouch cells using a three-electrode electrochemical approach for anode pre-lithiation.
Disclosed herein, an unexpected process has been developed for use with the three-electrode system discussed above which improves anode pre-lithiation efficiency in large format cells. Accordingly, an example method for improving a capacity of a lithium ion battery by improving an efficiency of anode pre-lithiation in large format cells is depicted at
As provided above, the disclosed process herein has been developed for use with three-electrode systems and improves anode pre-lithiation efficiency. Specifically, with this method the anode pre-lithiation efficiency is inversely related to anode loading amount under conditions where the anode is pre-lithiated via three-electrode systems (e.g., the electrochemical strategies of
Accordingly, turning to
Turning now to
Using the process of
Table 1 depicts example formation data of double-layered cells formed via the process flow of
In the example of Table 1, the control group (control cell 1 and control cell 2) included cells without any pre-lithiation step. Alternatively, cells labeled as three-electrode (Li)-1 and three-electrode (Li)-2 included cells prepared via the process of
The cells depicted at Table 1 were tested for cycling performance. Turning now to
The prelithiation strategy of
Referring to Table 2, the control group (control cell-1 and control cell-2) included cells without any prelithiation as baseline. Alternatively, cells labeled as three-electrode (Li)-1 and three-electrode (Li)-2 included cells prepared via the process of
The cells of Table 2 were also tested for cycling performance. Turning now to
The above discussion with regard to
Referring to example Table 3, the control group (control cell-1 and control cell-2) included cells without any pre-lithiation as baseline. Alternatively, cells labeled as three-electrode (LFP)-1 and three-electrode (LFP)-2 included cells prepared via the process of
The cells depicted at Table 3 were also tested for cycling performance. Turning now to
The prelithiation strategy of
Referring to example Table 4, the control group (control cell-1 and control cell-2) included cells without any pre-lithiation as baseline. Alternatively, cells labeled as three-electrode (LFP)-1 and three-electrode (LFP)-2 included multi-layered cells prepared via the process of
The cells depicted at Table 4 were also tested for cycling performance. Turning now to
Thus, double-layered cells prepared via the process of
In order to increase anode pre-lithiation efficiency in large-format cells, a process has herein been developed which determines an anode loading amount relative to anode pre-lithiation. Accordingly, turning to
Proceeding to step 604, method 600 includes determining the anode loading amount, or in other words, the anode coat weight (e.g., in g/m2 or in mAh/cm2). Specifically, anode loading amount may be determined based on electrochemical cell design, for example. Anode loading amount may be determined, for example, based on a desired capacity of a particular electrochemical cell design. Without a proper anode loading amount, anode pre-lithiation efficiency may be reduced or degraded, which may thus adversely impact improvements to discharge capacity and initial coulombic efficiency. In some examples, determining anode loading amount may be a function of the anode itself, such as whether the anode is graphite, silicon/graphite, silicon oxide/graphite, etc. In some examples, there may be a lower threshold, for which anode loading cannot be lower than for a particular application. As an example, anode loading may not be selected to be lower than 100 g/m2 or an areal capacity of lower than 3.5 mAh/cm2 for battery applications that include electric vehicles. Unless indicated otherwise, as used herein, anode loading and areal capacity values may correspond to a double-layered or double-sided coating (that is, a coating of two opposite sides of a current collector).
Thus, in some examples, anode loading for a large format cell may be in a range of 100 g/m2-190 g/m2. In some examples, anode loading for a large format cell may be in a range of 105 g/m2-175 g/m2. In other examples, anode loading for a large format cell may be in the range of 125-165 g/m2. In other examples, anode loading for a large format cell may be in the range of 130-160 g/m2. In other examples, anode loading for a large format cell may be in the range of 140-160 g/m2. In still other examples, anode loading for a large format cell may be in the range of 150-160 g/m2. As an example, it may be desirable to use high loading for electric vehicle cells with energy density of >250 Wh/kg. In some examples, anode loading for a large format cell may include an areal capacity in a range of 3.5 mAh/cm2 to 13 mAh/cm2. For example, anode loading for the large format cell may include the areal capacity in a range of 3.5 mAh/cm2 to 6.5 mAh/cm2 on a per layer basis. Accordingly, anode loading for a double-layered large format cell may be doubled, such that anode loading for the double-layered large format cell may include the areal capacity in a range of 7 mAh/cm2 to 13 mAh/cm2.
With the anode loading amount determined, method 600 may proceed to 606. At 606, method 600 includes loading the anode to the determined amount. Loading the anode to the determined amount may include mixing a slurry to obtain a homogeneous dispersion of each ingredient, and then applying the slurry to a current collector via a coating technology, such as slot die.
With the anode loaded to the determined amount, method 600 may proceed to 608. At 608, method 600 includes pre-lithiating the anode to an extent that is a function of the determined anode loading amount. Pre-lithiating the anode may be accomplished similar to that discussed at step B of
The method of
As an example, for a large format cell with increased layers and dimensions (such as a jelly roll design), efficiency and uniformity of the anode pre-lithiation may decrease due to overpotential as well as differential degree of lithiation in each layer during the pre-lithiation step. Such issues are not specific to jelly roll designs, but are relevant to other designs as well. Such issues may thus affect the improvement of initial efficiency and discharge capacity, as compared to small pouch cells. Thus, while the method of
Method 650 begins at 652 and includes determining cell design and anode loading (g/m2). It may be understood that the anode may include graphite, Si/graphite, SiOx/graphite, and even Si, SiOx, Sn, SnOx or combinations thereof. For example, depending on the cell design an amount of anode loading may be different for achieving uniform and efficient anode pre-lithiation.
Specifically, as mentioned briefly above, for large format cells that may have increased layers and dimensions, the amount of anode loading may impact efficiency and uniformity of the pre-lithiation step, whereas for small pouch cells anode loading may not be as critical a parameter. As an example, higher amounts of anode loading may make the anode thicker, which may not be favorable for efficient and uniform anode pre-lithiation for large format cells where the anode is of a substantially longer length that the anode of small pouch cells. However, for large format cells anode loading cannot be too low or else battery capacity may be compromised depending on the downstream application. As an example, anode loading of less than about 100 g/m2 or an areal capacity of less than 3.5 mAh/cm2 may not be useful for battery applications that include electric vehicles.
Thus, similar to that discussed above with regard to the method of
Proceeding to step 654, method 650 includes preparing and processing the anode based on the anode loading amount determined at step 652. Preparing and processing the anode may include the steps of coating the anode to achieve the desired amount of anode loading determined at step 652. Then, at step 656, method 650 includes assembling a jelly roll that includes the anode prepared at step 654 and a cathode. If the large format electrochemical cell design is not a jelly roll design, then at step 656, method 650 may include assembling the anode and the cathode in a manner in line with the desired design.
Proceeding to 658, method 650 includes determining the pre-lithiation level desired for the particular large format cell. Specifically, the pre-lithiation level and anode loading amount may be selected in a mutually dependent manner, or in other words, may be selected together. For example, anode pre-lithiation efficiency may decrease as anode loading increases, however there may be an upper limit for pre-lithiation which may not be larger than initial coulombic efficiency of the cathode half-cell (e.g., 91%). Here, the energy density may not be able to be improved to reach the expected value if anode loading were too low. However, with anode loading too high, improvements to the pre-lithiation efficiency may be constrained. Thus, both anode loading amount and pre-lithiation level may be considered together in a mutually dependent manner in order to achieve a specific high energy density cell.
With the pre-lithiation level determined, method 650 includes preparing the auxiliary electrode (e.g., the auxiliary electrode at
Determining the pre-lithiation level may be a function of the cell design and anode loading amount. Pre-lithiation percentage of the anode may be between a range of 5%-30% depending on the cell design. As one example, as silicon percentage of the anode increases, pre-lithiation percentage may increase as well. In other words, as silicon percentage increases, pre-lithiation percentage may be increased as compensation to achieve a target energy density.
Proceeding to 660, method 650 includes preparing the pouch that includes the jelly roll and auxiliary electrode. In other words, at step 660 the jelly roll is placed into a prepared pouch, along with the auxiliary electrode, similar to that, for example, as step A of
Continuing to step 664, method 650 includes conducting the electrochemical pre-lithiation of the anode, similar to that discussed above at step B of
In response to the anode being pre-lithiated to the desired percentage at 664, method 650 may proceed to 666. At 666, method 650 includes removing the auxiliary electrode. For example, the auxiliary electrode may be removed in similar fashion as that discussed above at step C of
Continuing to step 668, formation and grading analysis may be conducted on the large format cell.
Turning to
As discussed above with regard to the method of
Specifically, for illustrative purposes the strategy of
Table 5 depicts formation data of large format cells with anode loading 172 g/m2 after 6.5% pre-lithiation as compared to control large format cells with anode loading 172 g/m2 with no pre-lithiation.
As indicated in example Table 5, for the pre-lithiated cell, discharge capacity was increased about 3.1 Ah under 0.1C and 2.4 Ah under 0.3C. Initial coulombic efficiency was improved about 4.5%.
Table 6 depicts formation data of large format cells with anode loading of 190 g/m2 after 20% pre-lithiation as compared to control large format cells with anode loading 190 g/m2 without pre-lithiation.
As indicated at example Table 6, for the pre-lithiated cells discharge capacity was increased about 1.65 Ah under 0.1C and about 1.45 Ah under 0.3C, and the initial coulombic efficiency increased by about 2%. Thus, comparison of the results of Table 5 with those of Table 6 indicates that the extent of improvement in terms of discharge capacity and initial coulombic efficiency for the cell loaded to 172 g/m2 and where the anode is pre-lithiated to 6.5% is not similarly observed for the cell loaded to 190 g/m2 even under 20% pre-lithiation. The large difference in improvement in terms of discharge capacity and initial coulombic efficiency for the two large format cells discussed with regard to example Table 5 and example Table 6 illustrates the importance of anode loading for the electrochemical pre-lithiation process such as that depicted at
As another representative example, large format cells with high pre-lithiation percentage but lower anode loading (e.g., lower than the anode loading depicted above for table 5) were prepared using the process flow of
Depicted at Table 7 are four different cells prepared as discussed. Comparison of Table 7 with the data of Table 6 illustrates that initial coulombic efficiency increased dramatically with 20% pre-lithiation when anode loading was 158 g/m2 as compared to 20% pre-lithiation when anode loading was 190 g/m2. As shown at Table 7, initial coulombic efficiency improved to approximately 90% (as used herein, “approximately” when referring to a numerical value may encompass a deviation of 2% or less). As further indicated, initial coulombic efficiency may be greater than 90% for the large-format cells of Table 7. Furthermore, the energy density of the pre-lithiated cells of Table 7 is able to achieve 300 Wh/kg. Because the prelithiation efficiency is related to anode loading in large-format cells, higher loading may be associated with a thick electrode which may increase the impedance between anode and auxiliary electrode, which may thus prevent a successful anode prelithiation.
Turning now to
Comparison of formation data between large-format cells with different voltage control and pre-lithiation percentage at the pre-lithiation step is shown below at Table 8.
As indicated at Table 8, the first pre-lithiated cell 805 (pre-lithiated cell-1) that was pre-lithiated at a voltage around 0V showed a 3.1 Ah increase in discharge capacity with 6.5% pre-lithiation under 0.1C current density, and a 2.4 Ah increase in discharge capacity with 6.5% pre-lithiation under 0.3C current density. For the first pre-lithiated cell 805, the initial coulombic efficiency improved about 4.5%. The second pre-lithiated cell 810 (pre-lithiated cell-2) didn't show significant improvement in discharge capacity and initial coulombic efficiency when the voltage was around −2V at the pre-lithiation step, as compared to the first pre-lithiated cell 805. The data presented at Table 8 indicates that the voltage control of the pre-lithiation step is also important to the efficiency of the pre-lithiation process. The lithium ion may be reduced to Li metal at the anode surface when the voltage is too low. From the results depicted at Table 8 it may be understood that the anode of the second pre-lithiated cell 810 couldn't be pre-lithiated with the expected amount of lithium ion at the prelithiation step.
The electrochemical performance of pre-lithiated cells using the process of
Table 9 shows formation data for double-layered cells generated by either the SLMP method as discussed above, or the methodology of
As indicated at Table 9, there was not much difference in discharge capacity improvement for the SLMP method (SLMP pre-lithiation-1 and SLMP pre-lithiation-2) as compared to the Li metal auxiliary electrode method of
Ultra-thin Li foil represents another Li source used for anode pre-lithiation. The degree of pre-lithiation depends on the lithium amount deposited on the copper. To compare the electrochemical performance of pre-lithiated cells using the process of
Table 10 shows formation data for double-layered cells generated by either the ultra-thin foil method as discussed above, or the methodology of
Similar to that observed for the SLMP method as discussed above with regard to table 8, the discharge capacity improvement was similar between cells prepared via the ultra-thin Li foil methodology (ultra-thin Li Foil-1 and ultra-thin Li foil-2) as compared to cells prepared via the process of
Challenges to the pre-lithiation method using the ultra-thin Li foil included controllability of the rate and amount for pre-lithiation. Specifically, the ultra-thin foil reacts with the anode very fast and thus the rate of pre-lithiation is high. Consequently, pre-lithiation may not be conducted uniformly at the anode side, and this non-uniformity may influence the cycling performance of the cell. Another challenge to the pre-lithiation method using the ultra-thin Li foil included the fact that the amount of pre-lithiation was not easy to control because the amount of pre-lithiation is based on the thickness of the customized ultra-thin Li foil. Thus, changing the pre-lithiation amount for an anode includes generating new customized ultra-thin Li foil with a new thickness. This may increase costs associated with using the ultra-thin Li foil methodology, which may be avoided by using the process of
In another example, pre-lithiation may be processed via another electrochemical method. Specifically, with another electrochemical approach, the pre-lithiation of the anode was conducted in a specific fixture with a piece of sacrificing cathode as the lithium source. The fixture may be filled with electrolyte and connected to an electrochemical workstation to run charge process with a small constant current. The rate of pre-lithiation was controlled by current density. In such a method, a degree of pre-lithiation could be adjusted by modifying the time of charge process. In order to compare this electrochemical method with the methodology of
Table 11 shows formation data for double-layered cells generated by either the above-mentioned electrochemical method as discussed above, or the methodology of
As indicated at Table 11, there was not much difference in discharge capacity improvement for the electrochemical approach (electrochemical-1 and electrochemical-2) as compared to the Li-metal auxiliary electrode method of
The reason for the cycling performance being much better for the cells prepared via the methodology of
The above comparisons with regard to Tables 9-11 and
Accordingly, Table 12 shows formation data for double-layered cells generated by either the above-mentioned SLMP method as discussed above, or the methodology of
As indicated at Table 12, similar improvements were seen in terms of discharge capacity and initial efficiency for cells prepared via the process of
Table 13 shows formation data for double-layered cells generated by either the above-mentioned ultra-thin Li foil method as discussed above, or the methodology of
As indicated at Table 13, similar improvements were seen in terms of discharge capacity and initial efficiency for cells prepared via the process of
Table 14 shows formation data for double-layered cells generated by either the above-mentioned electrochemical method as discussed above, or the methodology of
As indicated at Table 14, similar improvements were seen in terms of discharge capacity and initial efficiency for cells prepared via the process of
In this way, methods for improving a capacity of a lithium ion battery are provided. In one example, a method for improving a capacity of a lithium ion battery comprises providing a three-electrode system including a cathode, an anode, and an auxiliary electrode; determining an anode loading amount and loading the anode to the determined anode loading amount; and pre-lithiating the anode with lithium from the auxiliary electrode, where a pre-lithiation efficiency is based on the anode loading amount. A first example of the method further includes wherein the auxiliary electrode is a lithium metal electrode. A second example of the method, optionally including the first example of the method, further includes wherein the auxiliary electrode is a lithium iron phosphate electrode. A third example of the method, optionally including one or more of the first and second examples of the method, further includes wherein the anode is a silicon oxide/graphite anode. A fourth example of the method, optionally including one or more of the first through third examples of the method, further includes wherein the anode is a silicon/graphite anode or a graphite anode. A fifth example of the method, optionally including one or more of the first through fourth examples of the method, further includes wherein the pre-lithiation efficiency increases as the anode loading amount decreases. A sixth example of the method, optionally including one or more of the first through fifth examples of the method, further comprises controlling a rate at which the anode is pre-lithiated. A seventh example of the method, optionally including one or more of the first through sixth examples of the method, further includes controlling the rate includes adjusting a current density for pre-lithiating the anode. An eighth example of the method, optionally including one or more of the first through seventh examples of the method, further comprises controlling a degree to which the anode is pre-lithiated. A ninth example of the method, optionally including one or more of the first through eighth examples of the method, further includes wherein controlling the degree includes controlling a duration over which the anode is pre-lithiated. A tenth example of the method, optionally including one or more of the first through ninth examples of the method, further includes wherein the anode loading amount comprises a loading on opposing sides of a current collector of the anode of greater than or equal to 100 g/m2 or an areal capacity of greater than or equal to 7 mAh/cm2. An eleventh example of the method, optionally including one or more of the first through tenth examples of the method, further includes wherein the anode loading amount comprises a loading on opposing sides of a current collector of the anode of less than or equal to 190 g/m2 or an areal capacity of less than or equal to 13 mAh/cm2. A twelfth example of the method, optionally including one or more of the first through eleventh examples of the method, further includes wherein pre-lithiating the anode includes pre-lithiating the anode to a predetermined pre-lithiation percentage, the predetermined pre-lithiation percentage being from 5% to 30%. A thirteenth example of the method, optionally including one or more of the first through twelfth examples of the method, further includes wherein improving the capacity includes the lithium ion battery having an initial coulombic efficiency of approximately 90%. A fourteenth example of the method of the method, optionally including one or more of the first through thirteenth examples of the method, further includes wherein improving the capacity includes the lithium ion battery having a first discharge capacity under 0.1C greater than 83 ampere hours. A fifteenth example of the method, optionally including one or more of the first through fourteenth examples of the method, further includes wherein improving the capacity includes the lithium ion battery having a second discharge capacity under 0.3C greater than 82 ampere hours. A sixteenth example of the method, optionally including one or more of the first through fifteenth examples of the method, further comprises removing the auxiliary electrode after pre-lithiating the anode. A seventeenth example of the method, optionally including one or more of the first through sixteenth examples of the method, further includes wherein pre-lithiating the anode includes electrochemically pre-lithiating the anode, where lithium ions from the auxiliary electrode migrate through an electrolyte solution to intercalate or alloy with the anode.
In another example, a method for manufacturing a large format electrochemical cell comprises providing a three-electrode system including a cathode, an anode, and an auxiliary electrode; determining an anode loading amount based on a desired design and application of the large format electrochemical cell; loading the anode to the anode loading amount; including the cathode, the anode, and the auxiliary electrode in the large format electrochemical cell; filling the large format electrochemical cell with an electrolyte solution; electrochemically pre-lithiating the anode to a desired pre-lithiation amount based on the anode loading amount; removing the auxiliary electrode, and vacuum sealing the large format electrochemical cell including the anode and the cathode. A first example of the method further includes wherein the auxiliary electrode is a lithium metal electrode or a lithium iron phosphate electrode. A second example of the method, optionally including the first example of the method, further includes wherein the anode is a silicon oxide/graphite anode or a silicon/graphite anode. A third example of the method, optionally including one or more of the first and second examples of the method, further includes wherein removing the auxiliary electrode includes forming a heat seal to seal the anode and the cathode from the auxiliary electrode, and then cutting the large format electrochemical cell along the heat seal. A fourth example of the method, optionally including one or more of the first through third examples of the method, further includes wherein subsequent to electrochemically pre-lithiating the anode and removing the auxiliary electrode, the anode is not exposed to oxygen or moisture. A fifth example of the method, optionally including one or more of the first through fourth examples of the method, further includes wherein the anode loading amount is for two opposite sides of a current collector of the anode and the anode loading amount is determined from a range of 100 g/m2 to 190 g/m2 or an areal capacity of 7 mAh/cm2 to 13 mAh/cm2. A sixth example of the method, optionally including one or more of the first through fifth examples of the method, further includes wherein the desired pre-lithiation amount of the anode is between 5% and 30% pre-lithiation. A seventh example of the method, optionally including one or more of the first through sixth examples of the method, further comprises controlling a rate and a degree at which the anode is pre-lithiated by controlling a current density and a duration for electrochemically pre-lithiating the anode. An eighth example of the method, optionally including one or more of the first through seventh examples of the method, further includes wherein electrochemically pre-lithiating the anode includes electrically connecting the anode to the auxiliary electrode.
In still another example, a large format electrochemical cell may be fabricated by a process comprising the steps of:
(a) preparing an anode in a process comprising the steps of:
(b) providing a cathode and an auxiliary electrode and including the anode, the cathode and the auxiliary electrode in the large format electrochemical cell;
(c) bathing the cathode, the anode, and the auxiliary electrode in an electrolyte solution;
(d) electrically connecting the anode and the auxiliary electrode to pre-lithiate the anode to a desired level, wherein the desired level of pre-lithiation of the anode is between 5% and 30% pre-lithiation; and
(e) removing the auxiliary electrode and sealing the large format electrochemical cell.
A first example of the large format electrochemical cell further includes wherein a rate at which the anode is pre-lithiated to the desired level is controlled by adjusting a current density at which the anode is pre-lithiated. A second example of the large format electrochemical cell, optionally including the first example of the large format electrochemical cell, further includes wherein removing the auxiliary electrode includes forming a heat seal to melt opposite sides of the large format electrochemical cell together, and then cutting the large format electrochemical cell along the heat seal. A third example of the large format electrochemical cell, optionally including one or more of the first and second examples of the large format electrochemical cell, further includes wherein the desired level of anode pre-lithiation is a function of the determined total anode loading weight. A fourth example of the large format electrochemical cell, optionally including one or more of the first through third examples of the large format electrochemical cell, further includes wherein the large format electrochemical cell has an energy density of 300 watt-hours/kilogram. A fifth example of the large format electrochemical cell, optionally including one or more of the first through fourth examples of the large format electrochemical cell, further includes wherein the large format electrochemical cell has an initial coulombic efficiency of greater than 90%. A sixth example of the large format electrochemical cell, optionally including one or more of the first through fifth examples of the large format electrochemical cell, further includes wherein the large format electrochemical cell has a first discharge capacity under 0.1C of greater than 83 ampere hours. A seventh example of the large format electrochemical cell, optionally including one or more of the first through sixth examples of the large format electrochemical cell, further includes wherein the large format electrochemical cell has a second discharge capacity under 0.3C of greater than 82 ampere hours. An eighth example of the large format electrochemical cell, optionally including one or more of the first through seventh examples of the large format electrochemical cell, further includes wherein the anode is a silicon oxide/graphite anode or a silicon/graphite anode. A ninth example of the large format electrochemical cell, optionally including one or more of the first through eighth examples of the large format electrochemical cell, further includes wherein the auxiliary electrode is lithium metal or lithium iron phosphate.
The following claims particularly point out certain combinations and sub-combinations regarded as novel and non-obvious. These claims may refer to “an” element or “a first” element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and/or properties may be claimed through amendment of the present claims or through presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, also are regarded as included within the subject matter of the present disclosure.
The present application claims priority to U.S. Provisional Application No. 62/860,686, entitled “ANODE PRE-LITHIATION FOR HIGH ENERGY LI-ION BATTERY,” and filed on Jun. 12, 2019. The entire contents of the above-identified application are hereby incorporated by reference for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 62860686 | Jun 2019 | US |
