NO20221238A1

NO20221238A1 - Method for re-lithiating a de-lithiated lfp cathode

Info

Publication number: NO20221238A1
Application number: NO20221238A
Authority: NO
Inventors: Fengliu Lou; Rasim Batmaz
Original assignee: Beyonder As
Priority date: 2022-11-17
Filing date: 2022-11-17
Publication date: 2024-05-20
Also published as: WO2024107062A1

Description

METHOD FOR RE-LITHIATING A DE-LITHIATED LFP CATHODE

The invention relates to a method for re-lithiating a de-lithiated lithium iron phosphate (LiFePO4) / LFP cathode, and to methods for pre-lithiating one or more anodes using the re-lithiated LFP cathode. The invention further relates to a device for re-lithiating a delithiated LFP cathode.

An energy storage device is a device that can store electrical energy, for example batteries, supercapacitors, and metal-ion capacitors. Energy storage devices generally comprise a plurality of energy storage cells, and each cell comprises a negative electrode that is also referred to as the anode, a positive electrode that is also referred to as the cathode, an electrolyte to allow diffusion of charge carrier ions, and a separator to prevent the electrodes from contacting each other while still allowing diffusion of ions. The anode and cathode typically comprise a layer of active material on each side of a current collector, and each cell may comprise a plurality of anodes and cathodes stacked on top of each other, or alternatively one or a few rolled into a jelly roll. The current collectors of the anodes are typically connected to each other at an anode tab at one side, while the current collectors of the cathodes are connected to each other at a cathode tab, often at the same or opposite end of the energy storage cell than the anode tab.

Metal-ion batteries, such as lithium-ion batteries (LIBs) generally have insertion materials with faradaic charge-storage mechanism. During charging, the metal ions will be extracted from the cathode and diffuse through the electrolyte to intercalate or alloy in the anode, while the reverse reaction will occur during discharging. The anode material for metal-ion batteries may for example comprise intercalation materials such as graphite, hard carbon, or soft carbon, but also alloying materials such as silicon. The cathode materials may comprise materials with a high concentration of metal ions and a high electrode potential. Metal-ion batteries are characterized by a high energy density, but a relatively low power density and cyclability.

Supercapacitors have a different charge-storage mechanism, where metal ions and ani-

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ons from the electrolyte will adsorb onto the surface of each electrode upon charging, respectively, and be released back into the electrolyte upon discharging. Since supercapacitors rely on the non-faradaic charge storage mechanism of surface adsorption, their electrodes generally comprise materials with a large surface area such as activated carbon. Supercapacitors are characterized by a high power density and cyclability, but a relatively low energy density.

Metal-ion capacitors such as lithium-ion capacitors (LICs) are hybrid energy storage devices which integrate a metal-ion battery anode, for example graphite or hard carbon, and a supercapacitor cathode, typically activated carbon, together. Therefore, they exhibit a high specific power, a good cyclic stability, and a moderate specific energy, so they have a wide range of potential applications. However, since neither the anode nor the cathode contains inherent metal ions, it is necessary to pre-dope the metal-ion capacitor with metal ions as charge carriers to run it properly. Metal-ion pre-doping may also lower the electrode potential of the anode to further increase the energy density. Taking a LIC as an example, pre-lithiation of the anode with lithium ions is performed to lower the potential of the anode, thereby widening the operation voltage window, and increasing the specific energy of the device.

Pre-doping of batteries, such as pre-lithiation of LIBs, may also be advantageous to reduce the negative effect of the loss of metal ions consumed during formation of the solidelectrolyte interphase or due to undesired side reactions during the lifetime of the battery. Pre-lithiation is a complicated process, and various methods have been investigated to find a solution which is safe and efficient for use in industrial scale.

LIBs have dominated the market of power sources for portable electronics and electric vehicles (EVs) owing to their high energy density, high Coulombic efficiency, technical maturity, decreasing production costs, and long cycling life. The increased use of LiBs leads to a substantial growth of spent, i.e. used, LIBs, resource scarcity, and increased raw material cost. In 2017, sales of electric vehicles exceeded one million cars per year worldwide for the first time. Making conservative assumptions of an average battery pack weight of 250 kg and volume of half a cubic metre, the resultant pack wastes would comprise around 250,000 tonnes and half a million cubic metres of unprocessed pack waste, when these vehicles reach the end of their lives. This emphasizes the need for proper recycling of spent batteries; otherwise, LIBs may not be sustainable in the long term and may also adversely impact the environment.

P30625NO00 description and claims_prio

Pyrometallurgical and hydrometallurgical recycling are currently the most mature LIB recycling technologies in which cathode active materials are broken down into elemental (i.e., pyrometallurgical) or molecular (i.e., hydrometallurgical) form to recover the valuable components. The recovered components need to be further processed to turn them into cathode active materials. For example, among the degradation mechanisms of cathode material, lithium lost via solid-electrolyte interphase (SEI) formation is considered a major cause of capacity fade, so it is necessary to replenish the cathode active material with lithium ions. As the known methods are highly energy intensive, costly, and involve the use of toxic solvent extractions, there remains a need for means for recycling LIBs that is safer and more cost and resource effective.

Solid-state synthesis has been investigated for cathode material regeneration (Nie, H. et al. LiCoO2: Recycling from spent batteries and regeneration with solid state synthesis. Green Chem. 17, 1276-1280 (2015)). In this method, end of life (EOL) LiCoO2 was calcined with predetermined amount of supplementary Li2CO3 powder to yield material that has compatible physical, chemical, and electrochemical properties with commercial LiCoO2. However, since each individual cell may have different lithium losses, this approach needs to quantify lithium addition for each batch of material processing. Similar regeneration process by direct heat treatment was also investigated for LiFePO4 (LFP) and Li(Ni1/3Co1/3Mn1/3)O22 (Song, X. et al. Direct regeneration of cathode materials from spent lithium iron phosphate batteries using a solid phase sintering method. RSC Adv.7, 4783–4790 (2017), Chen, J. et al. Environmentally friendly recycling and effective repairing of cathode powders from spent LiFePO4 batteries. Green Chem. 18, 2500–2506 (2016), and Zhang, X. et al. Sustainable Recycling and Regeneration of Cathode Scraps from Industrial Production of Lithium-Ion Batteries. ACS Sustain. Chem. Eng. 4, 7041– 7049 (2016)). The hydrothermal treatment happens in an autoclave at 180–220 °C. Increased rate capability was observed compared with solid-state synthesis approach.

Shi and co-workers reported an ambient-pressure re-lithiation process for degraded LiNi0.5Co0.2Mn0.3O2 via eutectic Li solutions (Shi, Y., Zhang, M., Meng, Y. S. & Chen, Z. Ambient-pressure re-lithiation of degraded LixNi0.5Co0.2Mn0.3O2 (0< x< 1) via eutectic solutions for direct regeneration of lithium-ion battery cathodes. Adv. Energy Mater. 9, 1900454 (2019)). Combining such re-lithiation process with a thermal annealing step, the LiNi0.5Co0.2Mn0.3O2 can be regenerated to their original composition and structure. However, in these regeneration processes, EOL cathode materials were harvested by physical or chemical means before going through a regeneration process.

P30625NO00 description and claims_prio

An electrochemical re-lithiation process for reusing cathode material can eliminate the need for a material harvesting step. The electrodes from a disassembled cell can be submerged in an electrolyte solution to regenerate them. Smith et al (Smith, K. A. et al. Methods and devices for electrochemical re-lithiation of lithium-ion batteries (2022)) reported the use of a lithium film to regenerate the lithium deficient cathode material by applying a voltage in a lithium organic electrolyte solution. This method can efficiently restore the stoichiometry of the cathode material. However, safety issues may arise from the lithium metal used in the counter electrode which potentially hinder the scale-up of the recycling process. Another attempt was to electrochemically regenerate LiCoO2 in an aqueous electrolyte solution (Zhang, L., Xu, Z. & He, Z. Electrochemical Relithiation for Direct Regeneration of LiCoO2 Materials from Spent Lithium-Ion Battery Electrodes. ACS Sustain. Chem. Eng. 8, 11596-11605 (2020). A platinum plate was used as the anode electrode instead of a lithium foil. This eliminates the safety issues of lithium foil and organic electrolytes and reduces the cost by using cheaper lithium salts, preventing organic electrolyte and avoid the use of dry room. However, an annealing step is still required for the electrode to be useable.

The invention has for its object to remedy or to reduce at least one of the drawbacks of the prior art, or at least provide a useful alternative to prior art. The object is achieved through features, which are specified in the description below and in the claims that follow. The invention is defined by the independent patent claims, while the dependent claims define advantageous embodiments of the invention.

In a first aspect, the invention relates to a method for re-lithiating a de-lithiated lithium iron phosphate (LFP) cathode, wherein the method comprises the steps of: providing a delithiated LFP cathode; assembling a re-lithiation cell comprising the de-lithiated LFP cathode with a suitable counter electrode, wherein the LFP cathode and counter electrode are arranged at least partly in an aqueous electrolyte comprising a lithium salt; and applying a current between the LFP cathode and the counter electrode to supply the LFP cathode with electrons. When electrons are supplied to the cathode, lithium ions from the electrolyte will be inserted into the de-lithiated LFP material at the cathode to neutralize the charge difference, which will be referred to as re-lithiation of the de-lithiated LFP cathode. Simultaneously, oxygen gas may evolve at the counter electrode due to oxidation of water molecules. A de-lithiated LFP cathode is herein defined as a cathode comprising LFP as an active material wherein at least a portion of the lithium ions has been removed from the active material. The portion of the lithium ions that has been removed in the de-lithiated LFP cathode may for example be at least 10 %, at least 20%, or at least 50% of the origi-

P30625NO00 description and claims_prio

nal capacity of the active material. The de-lithiated LFP cathode may for example correspond to a used LFP cathode from a LIB after EOL. This method may therefore provide the deficient lithium back to the LFP active material in the process of recycling LFP LIBs. Apart from an optional rinsing and/or drying step to remove water, the re-lithiated LFP cathode may be used in a cell directly after being re-lithiated. No annealing step is required, and there is no need to disassemble the electrode into smaller components or constituents as in most prior art methods. Cathodes comprising LFP as active material have the further advantages of being cheaper and safer than cathodes comprising other active materials.

The counter electrode may comprise a material which does not involve in undesired electrochemical reactions in the potential window in which the counter electrode operates, i.e. be inert in this potential window, so that no unwanted by-products are produced. In some embodiments, the counter electrode may be practically inert, for example by being kinetically stable or forming a passivation layer, and the electrons may be obtained almost entirely by oxygen evolution at the counter electrode. The counter electrode may for example be or comprise metals such as platinum (Pt) or gold (Au), or carbonaceous material such as activated carbon, carbon paper, or carbon cloth. Activated carbon has an extremely large surface area and thereby a large potential for oxygen evolution and electron supply. The carbonaceous material may be coated on a suitable current collector. In other embodiments, a counter electrode may be used which is fully or partly sacrificial, i.e. wherein the electrons are obtained at least partly by reactions and possibly dissolution of the sacrificial counter electrode, possible in addition to oxygen evolution. This may for example be aluminum or nickel.

The lithium salt may be compatible with LIB technology to avoid leftover chemicals and/or by-products from the re-lithiation process jeopardizing the safety and/or cycle life of a subsequent LIB. The lithium salt may be inexpensive and safe and may for example be lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium sulfate (Li2SO4), lithium nitrate (LiNO3), or lithium chloride (LiCl).

For an efficient, large-scale process, for example roll-to-roll, the re-lithiation time may be important. Therefore, to scale up the process, the re-lithiation may occur at a high rate which requires a relatively high charging current density. However, if the charging current becomes too high, it can lead to an increase in resistance and reduce the potential of the LFP cathode below H2 evolution potential, which may result in production of H2 gas on the cathode current collector and deterioration of the electrode integrity. The current may

P30625NO00 description and claims_prio

therefore be controlled to maintain the potential of the LFP cathode at a value which is in between the potential for lithium intercalation and the potential for hydrogen evolution.

In one embodiment, the method may include the step of replenishing the electrolyte with lithium ions. This step may be performed independently or simultaneously with any of the other steps of the method. It may for example be advantageous to perform the step of replenishing the electrolyte with lithium ions simultaneously with the step of applying a current between the LFP cathode and the counter electrode, since this will cause lithium ions to be incorporated into the LFP cathode and thereby be depleted from the electrolyte. Replenishment of the electrolyte may help to maintain the concentration of lithium ions in the electrolyte substantially constant, or at least within a desired range. It may be performed either continuously during one or more method steps, at specific points in the process, or when the lithium concentration is below a certain threshold concentration. The lithium-ion replenishment of the electrolyte may for example be performed by addition of a lithium salt, for example lithium hydroxide (LiOH). Lithium hydroxide has the additional benefit that the hydroxide ions will help to maintain the pH of the solution within a desired range by neutralizing H<+ >generated at the counter electrode during oxygen evolution.

In one embodiment, the method may additionally comprise the step of arranging the delithiated LFP cathode as a LFP cathode roll before the step of assembling a re-lithiation cell, and the step of assembling a re-lithiation cell may include at least partly unrolling the LFP cathode roll to immerse at least a portion of the LFP cathode in the aqueous electrolyte. In this way, re-lithiation of the LFP cathode may be performed as a roll-to-roll process, which may be faster and more cost-efficient than re-lithiation of individual, smaller LFP cathodes. The counter electrode is not required to be on a roll but may be arranged in the aqueous electrolyte in a static position. The size of the counter electrode may be chosen based on the required re-lithiation current.

In a second aspect, the invention relates to a method for pre-lithiating an anode for an energy storage device using the method according to the first aspect of the invention, wherein the method additionally comprises the steps of disassembling the re-lithiation cell, assembling a pre-lithiation cell comprising the re-lithiated LFP cathode and an anode, and charging the pre-lithiation cell to pre-lithiate the anode. In this way a de-lithiated LFP cathode may be re-lithiated and used to pre-lithiate an anode instead of being discarded.

In a third aspect, the invention relates to a method for pre-lithiating a plurality of anodes, wherein the method comprises the step of repeating the method according to the second

P30625NO00 description and claims_prio

aspect of the invention and using a new anode for each repetition. An advantage of this method is that pre-lithiation of multiple anodes can be accomplished by re-lithiating and reusing a single LFP cathode. More lithium salt may be added to the electrolyte when the concentration of lithium ions in the solution is below a certain threshold or between the pre-lithiation of each anode, each second anode, each third anode etc. Similarly, the electrolyte may be rinsed or exchanged based on the concentration of H<+ >ions or anions from the salt, or between the pre-lithiation of each anode, each second anode, each third anode etc. This is more sustainable and cost-effective than using a new LFP cathode for pre-lithiation of each new anode.

In a fourth aspect, the invention relates to a device for re-lithiating a de-lithiated LFP cathode, wherein the device comprises a container containing an aqueous electrolyte comprising a lithium salt; a suitable counter electrode immersed in the electrolyte; a first roller for unwinding the de-lithiated LFP cathode and a second roller for winding the re-lithiated LFP cathode onto, and at least one tension roller for keeping a portion of the LFP cathode immersed in the electrolyte. The suitable electrode may be chosen as described above, and the device may comprise a counter electrode on each side of the LFP cathode for homogenous re-lithiation on both sides. The device may comprise a treatment reservoir for monitoring the electrolyte and replenishing the electrolyte with lithium ions. A pump may ensure circulation and exchange of the electrolyte between the treatment reservoir and the container. The device may comprise two tension rollers for keeping a tensioned portion of the LFP cathode in the electrolyte and substantially parallel with the counter electrode.

In the following is described examples of preferred embodiments illustrated in the accompanying drawings, wherein:

Fig. 1 shows a re-lithiation cell;

Fig. 2 shows a re-lithiation cell as a roll-to-roll process;

Fig. 3 shows a charging voltage profile of a fresh LFP cathode vs lithium;

Fig. 4 shows a voltage profile during re-lithiation of a de-lithiated LFP cathode;

Fig. 5 shows a charging voltage profile of a re-lithiated LFP cathode vs lithium;

and

P30625NO00 description and claims_prio

Fig. 6 shows a charge and discharge voltage profile of an energy storage cell comprising a fresh LFP cathode and a hard carbon anode which has been pre-lithiated with a re-lithiated LFP cathode.

In the following are described examples of embodiments of the invention. In the drawings, the reference numeral 1 indicates a re-lithiation cell. The drawings are illustrated in a schematic manner, and the features therein are not necessarily drawn to scale. Identical reference numerals refer to identical or similar features in the figures.

Figure 1 shows a re-lithiation cell 1 as used in a method according to the invention. The re-lithiation cell 1 comprises a de-lithiated LFP cathode 3 and a counter electrode 5 partly immersed in an aqueous electrolyte 7 within a suitable container 9. The electrolyte 7 comprises a lithium salt, such as LiTFSI. The de-lithiated LFP cathode 3 and the counter electrode 5 are connected with an electrical connection 11 and a power supply 12 which allows a current to flow between the two electrodes 3, 5. By applying a current from the delithiated LFP cathode 3 to the counter electrode 5, i.e. supplying the LFP cathode 3 with electrons from the counter electrode 5, the potential of the de-lithiated LFP cathode 3 will decrease and lithium ions from the electrolyte 7 will be incorporated into the active material of the de-lithiated LFP cathode 3. The de-lithiated LFP cathode 3 will thereby be relithiated. The electrons from the counter electrode 5 may originate from the oxidation of the oxygen atoms of water molecules to O2 and H<+>, thereby releasing electrons.

Figure 2 shows a side view of a re-lithiation cell 1, wherein the de-lithiated LFP cathode 3 is re-lithiated using a roll-to-roll process. The roll-to-roll re-lithiation cell 1 comprises a container 9 containing electrolyte 7 and two plate-shaped counter electrodes 5. The LFP cathode 3 is electrically connected to each counter electrode 5 through a power supply (not shown). The de-lithiated LFP cathode 3 is in the form of a long sheet wound into a de-lithiated LFP cathode storage roll 13, which is positioned on a first roller 14 configured to unwind the de-lithiated LFP cathode 3. The LFP cathode 3 is then unwound from the de-lithiated LFP cathode roll 13 via tension rollers 15,17 at least partly into the electrolyte 7. Two tension rollers 17 are positioned in the electrolyte 7 to ensure that a straight and tensioned portion 19 of the LFP cathode 3 is arranged between and substantially parallel with the two counter electrodes 5. The tensioned portion 19 of the LFP cathode 3 preferably has substantially the same distance to each counter electrode 5 to ensure that the relithiation is substantially uniform and equal on each side of the LFP cathode 3. The tensioned portion 19 may be arranged so that O2 is not trapped below it as a large gas bubble causing an upward bulge. The tensioned portion 19 may for example be inclined to

P30625NO00 description and claims_prio

avoid trapping of the O2 gas and/or be supported with additional tension roller above it. After re-lithiation, the tensioned portion 19 will be translated further out of the electrolyte 7 and wound into a re-lithiated LFP cathode storage roll 21 on a second roller 22. This process may typically be performed as a continuous process. A cleaning step may be included before or after the re-lithiated LFP cathode 3 is wound into a re-lithiated LFP cathode storage roll 21. Since re-lithiation of the de-lithiated LFP cathode 3 consumes lithium ions, the electrolyte 7 is replenished with lithium ions via a treatment reservoir 23. The treatment reservoir 23 can also be used to monitor and rinse the electrolyte 7 and to adjust pH. When the electrons from the counter electrodes 5 are supplied by water oxidation and oxygen evolution, hydrogen ions (H<+>) will also be generated, which will make the electrolyte 7 more acidic. Addition of LiOH to the electrolyte will therefore have the double function of replenishing the electrolyte 7 with lithium ions and keeping the pH at the desired level. The container 9 and the treatment reservoir 23 are in fluid connection via two tubes 25, 27, and a pump 29 ensures exchange of electrolyte 7 between the treatment reservoir 23 and the container 9.

Examples

LFP cathode stability in aqueous electrolyte: LFP cathodes were fabricated with polyvinylidene fluoride (PVDF) binder and C65 carbon additive with a LFP:PVDF:C65 mass ratio of 92.5:2.5:5. The LFP cathodes can also be fabricated using other hydrophobic binders, such as polyacrylonitrile (PAN). De-lithiated LFP cathodes were generated by charging a fresh LFP electrode to 3.65 V (vs Li/Li<+>) in a coin-cell to remove the Li<+ >ions from LFP. The charging profile of a fresh LFP cathode vs Li/Li<+ >is shown in figure 3. To inspect their electrochemical stability in aqueous systems, the de-lithiated LFP cathodes were immersed in distilled water for 6 hours, dried in a vacuum oven overnight, and used to assemble coincells with lithium as the anode. The LFP cathodes were electrochemically active and delivered satisfactory capacity, thereby demonstrating that the LFP cathodes can be used to study electrochemical re-lithiation in aqueous systems.

Example 1: Re-lithiation of the de-lithiated LFP cathode was then performed by immersing the de-lithiated LFP cathode in an aqueous LITFSI electrolyte 0.1 M versus aluminum counter electrode. The counter electrode was a plate, but it could also have been a mesh. A constant current was applied to intercalate Li<+ >ions into the de-lithiated LFP cathode as shown in figure 4. The dip in potential value around 0.15 mAh may indicate that some other reaction occurs temporarily before stable oxygen evolution. The capacity of the relithiated LFP cathode was checked by assembling a coin cell using lithium chip as anode.

P30625NO00 description and claims_prio

Figure 5 shows the voltage profile of the re-lithiated LFP cathode that was charged up to 3.65 V (vs Li/Li<+>). The voltage profile for charging of the re-lithiated LFP cathode in figure 5 is similar to the voltage profile for charging of the fresh LFP cathode shown in figure 3, which indicates that the re-lithiation process was successful. In different repetitions of this experiment, the re-lithiation experiments succeeded to re-lithiate the de-lithiated LFP cathodes with capacity retention values between 85% to 100%.

To further demonstrate the success of the electrochemical re-lithiation method, a relithiated LFP cathode was used to pre-lithiate a hard carbon (HC) electrode. The prelithiated HC electrode was used to assemble a full cell vs a fresh LFP electrode to determine the initial Coulombic efficiency (ICE). The ICE was 94 %, and since this is significantly higher than that of non-pre-lithiated HC, which was around 72 %, the method has successfully pre-lithiated the HC anode, thereby proving that that the re-lithiated LFP cathode used in the pre-lithiation step had indeed been successfully re-lithiated. The charge and discharge voltage profile of the pre-lithiated HC vs fresh LFP is shown in figure 6, clearly showing a plateau with a relatively constant voltage typical of LFP cathode with a pre-lithiated HC anode.

Example 2 use the method of example 1, wherein the counter electrode is platinum instead of aluminum, and the electrolyte is lithium sulfate instead of LITFSI.

Example 3 uses the method of example 1, wherein the counter electrode is activated carbon instead of aluminum, and the electrolyte is lithium sulfate instead of LITFSI.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

P30625NO00 description and claims_prio

Claims

C l a i m s

1. Method for re-lithiating a de-lithiated LFP cathode (3), c h a r a c t e r -i z e d i n that the method comprises the steps of:

a. providing a de-lithiated LFP cathode (3);

b. assembling a re-lithiation cell (1) comprising the de-lithiated LFP cathode (3) with a suitable counter electrode (5), wherein the de-lithiated LFP cathode (3) and counter electrode (5) are arranged at least partly in an aqueous electrolyte (7) comprising a lithium salt, and

c. applying a current between the LFP cathode (3) and the counter electrode (5) to supply the LFP cathode (3) with electrons.

2. The method according to claim 1, wherein the counter electrode (5) comprises activated carbon.

3. The method according to claim 1 or 2, wherein the lithium salt is chosen from the group of LiTFSI, LiNO3, LiCl, and Li2SO4.

4. The method according to any of the preceding claims, wherein the current is controlled to maintain the potential of the LFP cathode (3) at a value which is in between the potential for lithium intercalation and the potential for hydrogen evolution.

5. The method according to any of the preceding claims, wherein the method additionally includes the step of replenishing the electrolyte (7) with lithium ions.

6. The method according to claim 5, wherein the step of replenishing the electrolyte (7) with lithium ions is performed by addition of lithium hydroxide to the electrolyte (7).

7. The method according to any of the preceding claims, wherein the method additionally comprises the step of arranging the de-lithiated LFP cathode (3) as a LFP cathode roll (13) before the step of assembling a re-lithiation cell (1), and wherein the step of assembling a re-lithiation cell (1) includes at least partly unrolling the LFP cathode roll (13) to immerse at least a portion of the de-lithiated LFP cathode (3) in the aqueous electrolyte (7).

P30625NO00 description and claims_prio

8. A method for pre-lithiating an anode for an energy storage device using the method according to any of the preceding claims, wherein the method additionally comprises the steps of:

a. disassembling the re-lithiation cell (1),

b. assembling a pre-lithiation cell comprising the re-lithiated LFP cathode (3) and an anode, and

c. charging the pre-lithiation cell to pre-lithiate the anode.

9. A method for pre-lithiating a plurality of anodes, wherein the method comprises the step of repeating the method according to claim 8 and using a new anode for each repetition.

10. A device for re-lithiating a de-lithiated LFP cathode (3), wherein the device comprises:

a. a container (9) containing an aqueous electrolyte (7) comprising a lithium salt;

b. a suitable counter electrode (5) immersed in the electrolyte (7);

c. a first roller (14) for unwinding the de-lithiated LFP cathode and a second roller (22) for winding the re-lithiated LFP cathode onto, and

d. at least one tension roller (17) for keeping a portion of the LFP cathode (3) immersed in the electrolyte (7),

P30625NO00 description and claims_prio