Method for preparing lithium composite foil with intermittent lithium strips on at least one side of collector foil

Abstract

Disclosed are methods and systems for preparing a lithium (Li) composite foil comprising multiple Li strips on at least one side of a collector foil with a gap between adjacent Li strips. In one embodiment, the method comprises: 1) providing a Li foil comprising a Li layer on a support layer; 2) cutting the Li layer of the Li foil, on a cutting device comprising two blades in parallel, into a precut Li foil comprising multiple Li strips; 3) via a pair of rollers with a slot on at least one of rollers, laminating the multiple Li strips to a collector foil while leaving the multiple Li interstrips uncompressed or less compressed as each interstrip fits into the slot; and 4) removing the multiple Li strips from the support layer.

Description

METHOD FOR PREPARING LITHIUM COMPOSITE FOIL WITH INTERMITTENT LITHIUM STRIPS ON AT LEAST ONE SIDE OF COLLECTOR FOILCROSS-REFERENCE

[0001] The present application claims the benefit of US Serial No. 63 / 622,128, filed January 18, 2024, the entire content of which is incorporated herein by reference into this application.FIELD

[0002] Disclosed are methods and systems for preparing a lithium (Li) composite foil with intermittent lithium strips on at least one side of a collector such as copper (Cu) foil.BACKGROUND

[0003] Lithium composite foil, such as Li-Cu composite foils, are used in making anodes for lithium metal batteries. Tabs are typically welded or otherwise attached to the composite foil and this step adds complexity to the anode manufacturing process. In addition, the weld strength of the tab is often not strong enough and the weld can break or deteriorate during manufacture. Accordingly, there is a need for new methods to form lithium composite foils from which tabs can be formed without the need to weld the tabs to the foil.SUMMARY

[0004] In one aspect, the present disclosure provides a method for preparing a lithium (Li) composite foil comprising multiple Li strips on at least one side of the collector foil with a gap (or spacing) between adjacent Li strips. In one embodiment, the method comprises: a) feeding a Li foil comprising a Li layer on a support layer, to a cutting device; b) cutting the Li layer on the support layer with the cutting device into a precut Li foil comprising multiple Li strips and multiple Li interstrips; c) feeding the precut Li foil and a collector foil through a rolling system comprising a first roller and an opposing second roller to laminate the multiple Li strips to the collector foil, wherein at least one of the first and second rollers comprises a slot such that the slot is aligned with the multiple Li interstrips such that the multiple Li interstrips are not laminated to the collector foil; and d) removing the multiple Li strips from the support layer,leading to a Li composite foil in which the multiple Li strips are on one side of the collector foil

[0005] In some embodiments, the lithium foil comprises lithium metal or lithium alloy. In some embodiments, the lithium alloy is an alloy of lithium metal with at least one element selected from the group consisting of C, Si, Sn, Ge, B, Al, In, Bi, Sb, Na, Mg, Zn, Au, and Ag. In some embodiments, the collector foil is made from a material selected from the group consisting of Cu, stainless steel, Ti, Ni, Ta, Mo, Nb, Sn, Zn, Ag, Au, and alloy thereof. In some embodiments, the collector foil is made of a material selected from Cu-Ni alloy, Cu-Zn alloy, Ni-Cr alloy and phosphor bronze.BRIEF DESCRIPTION OF THE FIGURES

[0006] Non-limiting embodiments of the present disclosure will be described by way of example with reference to the accompanying figures, which are schematic and are not intended to be drawn to scale. In the figures, each identical or nearly identical component illustrated is typically represented by a single numeral. For purposes of clarity, not every component is labeled in every figure, nor is every component of each embodiment of the disclosure shown where illustration is not necessary to allow those of ordinary skill in the art to understand the disclosure.

[0007] Fig. 1 shows an exemplary lithium foil comprising a lithium layer and a support layer according to some embodiments of the present disclosure.

[0008] Fig. 2 shows a top or plan view of an exemplary lithium foil comprising a lithium layer which is precut into lithium strips and interstrip according to one embodiment of the present disclosure.

[0009] Fig. 3 shows a top or plan view of multiple lithium strips on a support layer with the interstrip(s) removed according to some embodiments of the present disclosure.

[0010] Fig. 4A shows a side view of multiple lithium strips on one side of a support layer prior to lamination to a collector foil according to some embodiments of the present disclosure.

[0011] Fig. 4B shows a side view of multiple lithium strips laminated on one side of a collector foil according to some embodiments of the present disclosure.

[0012] Fig. 5A shows a side view of multiple lithium strips on a first support layer and multiple lithium strips on a second support layer prior to lamination to a collector foil according to some embodiments of the present disclosure.

[0013] Fig. 5B shows a side view of multiple lithium strips on both sides of a collector foil according to some embodiments of the present disclosure.

[0014] Fig. 6A shows a system for preparing a Li composite foil (61) according to some embodiments of the present disclosure.

[0015] Fig. 6B shows a system for preparing a Li composite foil (62) according to some embodiments of the present disclosure.

[0016] Fig. 7 shows an exemplary pair of rollers with one slot on each according to some embodiments of the present disclosure.

[0017] Fig. 8 shows an exemplary pair of rollers with the second roller having one slot according to some embodiments of the present disclosure.

[0018] Fig. 9 shows an exemplary pair of rollers with the first roller having one slot according to some embodiments of the present disclosure.

[0019] Fig. 10 shows an exemplary pair of rollers with each roller having two slots according to some embodiments of the present disclosure.

[0020] Fig. 11 shows an exemplary pair of rollers with the first roller having two slots according to some embodiments of the present disclosure.

[0021] Fig. 12A to Fig. 12D show an exemplary roller with one, two, three and four slots, respectively, according to some embodiments of the present disclosure.DETAILED DESCRIPTION

[0022] In one aspect, the present disclosure provides a method for preparing a lithium (Li) composite foil comprising multiple Li strips on at least one side of a collector foil with gapbetween adjacent Li strips. The methods described herein provide for intermittent lamination of spaced apart Li strips to a collector foil. The advantage of such a Li composite foil is that the exposed collector foil present in the gaps between the adjacent Li strips may be used to form tabs directly from the collector foil rather than welding (or otherwise attaching) tabs, thereby eliminating the step of welding tabs and avoiding welded tabs that often have inadequate strength. In some embodiments, the method for preparing a lithium (Li) composite foil includes: a) feeding a Li foil comprising a Li layer on a support layer, to a cutting device; b) cutting the Li layer on the support layer with the cutting device into a precut Li foil comprising multiple Li strips and multiple Li interstrips; c) feeding the precut Li foil and a collector foil through a rolling system comprising a first roller and an opposing second roller to laminate the multiple Li strips to the collector foil, wherein at least one of the first and second rollers comprises a slot such that the slot is aligned with the multiple Li interstrips such that the multiple Li interstrips are not laminated to the collector foil; and d) removing the multiple Li strips from the support layer, leading to a Li composite foil in which the multiple Li strips are on one side of the collector foil.

[0023] Fig. 1 shows top view an exemplary lithium foil (20) including a lithium layer (21) and a support layer (or support film) (22) that can be used according to some embodiments of the present disclosure. As discussed below, lithium foil (20) may be provided as a roll that is continuously fed as part of the manufacturing process. In some embodiments, the lithium layer (21) may be lithium metal or lithium alloy. In some embodiments, the lithium alloy is an alloy of lithium metal with at least one element selected from the group consisting of C, Si, Sn, Ge, B, Al, In, Bi, Sb, Na, Mg, Zn, Au, and Ag. In some embodiments, the Li layer has a thickness in a range from 5 pm to 100 pm, from 5 pm to 50 pm, from 5 pm to 40 pm, from 5 pm to 30 pm, from 5 pm to 20 pm, from 10 pm to 100 pm, from 10 pm to 50 pm, from 10 pm to 40 pm, from 10 pm to 30 pm, from 10 pm to 20 pm, from 15 pm to 100 pm, from 15 pm to 50 pm, from 15 pm to 40 pm, from 15 pm to 30 pm, or all and any ranges and subrangestherebetween. In some embodiments, the continuous Li layer has a width in a range from 40 mm to 500 mm, from 40 mm to 300 mm, from 40 mm to 250 mm, from 40 mm to 200 mm, from 40 mm to 150 mm, from 40 mm to 100 mm, from 60 mm to 500 mm, from 60 mm to 300 mm, from 60 mm to 250 mm, from 60 mm to 200 mm, from 60 mm to 150 mm, from 60 mm to 100 mm, from 75 mm to 500 mm, from 75 mm to 300 mm, from 75 mm to 250 mm, from 75 mm to 200 mm, from 75 mm to 150 mm, from 75 mm to 100 mm, or all and any ranges and subranges therebetween. In some embodiments, the support layer (22) has a width equal to or greater than that of the Li layer (21).

[0024] In some embodiments, the support layer comprises a polymer selected from the group consisting of polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), perfluoroalkoxy (PF A), polyvinyl chloride (PVC), polyimide (PI).

[0025] In some embodiments, the support layer (or support film) has a width in a range from 50 mm to 350 mm, from 50 mm to 300 mm, from 50 mm to 250 mm, from 50 mm to 200 mm, from 50 mm to 150 mm, from 50 mm to 100 mm, from 75 mm to 350 mm, from 75 mm to 300 mm, from 75 mm to 250 mm, from 75 mm to 200 mm, from 75 mm to 150 mm, from 75 mm to 100 mm, from 100 mm to 350 mm, from 100 mm to 300 mm, from 100 mm to 250 mm, from 100 mm to 200 mm, from 100 mm to 150 mm, or all and any ranges and subranges therebetween. In some embodiments, the collector foil has a width in a range from 50 mm to 350 mm, from 50 mm to 300 mm, from 50 mm to 250 mm, from 50 mm to 200 mm, from 50 mm to 150 mm, from 50 mm to 100 mm, from 75 mm to 350 mm, from 75 mm to 300 mm, from 75 mm to 250 mm, from 75 mm to 200 mm, from 75 mm to 150 mm, from 75 mm to 100 mm, from 100 mm to 350 mm, from 100 mm to 300 mm, from 100 mm to 250 mm, from 100 mm to 200 mm, from 100 mm to 150 mm, or all and any ranges and subranges therebetween.

[0026] Fig. 2 and Fig. 4 A show a lithium foil after a cutting (or pre-cutting step) comprising a lithium layer which is cut into lithium strips (31) and interstrip(s) (30) according to someembodiments of the present disclosure. As shown in Fig. 4A, the lithium foil is attached to one surface of support layer (22)

[0027] After the multiple lithium strips are laminated and transferred from the support layer (22) to a collector foil (24), the multiple lithium strips (31) are attached to the collector foil (24) as shown in Fig. 3 and Fig. 4B. As the Li interstrips remain on the support layer. Multiple gaps (or spacings) (32) are formed between adjacent lithium strips. The gaps (32) are exposed collector foil (24) which may be formed / shaped into tabs. In some embodiments, the Li strips (31) and gap(s) (32) have a length of LI and L2, respectively.

[0028] In some embodiments, collector foil (24) may be any material suitable for use as an anode tab. In some embodiments, the collector foil is made from a material selected from the group consisting of Cu, stainless steel, Ti, Ni, Ta, Mo, Nb, Sn, Zn, Ag, Au, and alloy thereof. In some embodiments, the collector foil is made of a material selected from Cu-Ni alloy, Cu- Zn alloy, Ni-Cr alloy and phosphor bronze. In some embodiments, the collector foil is Cu.

[0029] In some embodiments, the collector foil is configured to different formats including foil, meshed foil, foam, conductive carbon coated foil, composite foil with plastics as inner layer, and composite foil with metalized plastics (such as PET and PP).

[0030] In some embodiments, the collector foil, such as Cu foil, has a thickness in a range from 2 pm to 50 pm, from 2 pm to 40 pm, from 2 pm to 30 pm, from 2 pm to 20 pm, from 2 pm to 10 pm, from 2 pm to 7.5 pm, from 5 pm to 50 pm, from 5 pm to 40 pm, from 5 pm to 30 pm, from 5 pm to 20 pm, from 5 pm to 10 pm, from 5 pm to 7.5 pm, from 7.5 pm to 50 pm, from 7.5 pm to 40 pm, from 7.5 pm to 30 pm, from 7.5 pm to 20 pm, from 7.5 pm to 10 pm, from 10 pm to 50 pm, from 10 pm to 40 pm, from 10 pm to 30 pm, from 10 pm to 20 pm, or all and any ranges and subranges therebetween.

[0031] As will be described in more detail below, in some embodiments, lithium strips may be laminated on just a first surface of a collector foil (24) as shown in Fig. 4B and in other embodiments as shown in Figs. 5A and 5B, lithium strips may be laminated on both a firstsurface of collector (24) and a second, opposing, surface of collector (24). In some embodiments, prior to lamination with a collector foil (24), Fig. 5A shows multiple first lithium strips (31a) and multiple second lithium strips (31b) on a first and second support layer (22a and 22b), respectively. After lamination with the collector foil, multiple first lithium strips (31a) are on one side of the collector foil (24), while multiple second lithium strips (31b) are on the other side of the collector foil (24), leading to a Li composite foil (62) with lithium strips on both sides of the collector foil as shown in Fig. 5B.

[0032] As shown in Fig. 6A, a lithium foil (20) may be provided on a roll and is continuously fed to a cutting device where the Li foil is cut (precut) into a precut Li foil comprising the Li strips (31) and interstrips (30). The precut Li foil is then fed into a pair of rollers (41 and 42) together with a collector foil (24) to intermittently laminate Li strips (31) to collector foil (24). As shown in Fig. 6A, collector foil (24) may be provided on a roll and may be continuously fed to the rollers. The pair of rollers includes a first roller (41) and a second roller (42). Either or both rollers comprise a slot as illustrated and shown in Figs. 7-11 and 12A-12D. As used herein, a “slot” is an indentation, recess, cavity, or notch in the surface of the roller 41 and / or roller 42. The slot(s) are positioned on roller 41 and / or 42 to align with the interstrips (30) such that when the rollers are rolling, the interstrip fits into the slot. As a result, the interstrips (30) are uncompressed between the rollers (or at least insufficiently compressed) so that the interstrips (30) are not laminated to collector foil (24). As the Li foil (20) passes through the rollers (41, 42), Li strips (31) are not aligned with the slot(s) and are consequently compressed against, and laminated to, collector foil (24). Upon exiting rollers (41, 42) support layer (22) may be wound up and collected on a roll in such a manner that support layer is moved away from collector foil (24). As the interstrip is not subject to minimal, if any compression between rollers (41, 42), and is not laminated to collector foil (24), the interstrips (32) remain on the support layer (22) and is not bonded or attached to the collector foil. On the other hand, by removing / peeling from the support layer (22), the lithium strips are attached to the collectorfoil, thereby forming a Li composite foil (61). Optionally, the Li composite foil (61) is further rolled with another support layer (separate film) (26) to form a roll. The support layer (separate film) (26) is to separate the Li composite foil (61) from adhering to each other.

[0033] Fig. 6B shows a similar process and system as Fig. 6A, except it depicts an embodiment where a first lithium foil (20a) on a first support layer (22a) and a second lithium foil (20b) on a second support layer (22b) are intermittently laminated to opposite sides of a collector foil (24). First lithium foil (20a) is fed to a first cutting device and cut (precut) to a first precut Li foil comprising first li strips (31a) and interstrips (30a) on the first support layer. Second lithium foil (20b) is fed to a second cutting device and cut (precut) to a second precut Li foil comprising second li strips (31b) and interstrips (30b) on the second support layer. The first and second precut lithium foils are fed into a pair of rollers (41 and 42) together with a collector foil (24) to be sandwiched between the first and second precut Li foils. The pair of rollers comprises a first roller (41) and a second roller (42). Either or both rollers comprise a slot as illustrated and shown in Figs. 7-11 and 12A-12D. The slot(s) are positioned on roller 41 and / or 42 to align with the interstrips (30a and 30b) such that when the rollers are rolling, the interstrip fits into the slot(s). As a result, the interstrips (30a and 30b) are uncompressed between the rollers (or at least insufficiently compressed) so that the interstrips (30a and 30b) are not laminated to collector foil (24). Li strips (31a and 31b) are not aligned with the slot(s) as the Li foils (20a and 20b) pass through the rollers (41, 42) and are consequently compressed against and laminated to collector foil (24). Upon exiting rollers (41, 42) support layers (22a and 22b) may be wound up and collected on a roll in such a manner that support layers are moved away from collector foil (24). Since the interstrips (30a and 30b) are subject to little, if any, compression, the interstrips (30a and 30b) remain on the support layer (22a and 22b) respectively and are not bonded or attached to the collector foil. On the other hand, the lithium strips (31a and 3 lb) are attached to the collector foil (24) and transferred from the support layer (22a and 22b) to thecollector foil (24). Accordingly, a Li composite foil (62) is formed. Optionally, the Li composite foil (62) is rolled with another support layer (separate film) (26) to form a roll.

[0034] Various embodiments related to the rollers and slots are described with reference to Figs. 7-11 and Figs. 12A-D As shown in Fig. 7, in some embodiments, a pair of rollers comprises a first roller (41) and a second roller (42). The first roller (41) comprises a first slot (411), the second roller (42) comprises a second slot (421), and the first and second slots are aligned with each other. In some embodiments, each slot has the same length.

[0035] As shown in Fig. 8 and Fig. 9, the pair of the roller can be configured that only one roller has one or more slots while the other has no slots according to some embodiments of the present disclosure. As shown in Fig. 10, the first roller (41) comprises multiple first slots (411 and 412), while the second roller (42) comprises multiple second slots (421 and 422).

[0036] In some embodiments, the first roller (41) comprises two first slots (411 and 412) while the second roller has no slots.

[0037] In some embodiments, either roller has one or multiple slots. In some embodiments, the roller has one, two, three, and four slots in Fig. 12A, Fig. 12B, Fig. 12C, and Fig- 12D, respectively. When the roller has multiple slots, they are evenly distributed along the periphery of the roller and the arc length between adjacent slots is the same.

[0038] In one aspect, as shown in Fig. 6A (and Fig. 6B), the present disclosure provides a system of preparing a Li composite foil comprising multiple Li strips on at least one side of a collector foil. In some embodiments, the system comprises a cutting device which can cut (alternatively, precut) a Li foil comprising a continuous Li layer on a support layer into a precut Li foil comprising multiple Li strips and multiple Li interstrips on the support layer. In some embodiments, the cutting device comprises a pair of cutting blades. In some embodiments, the pair of cutting blades are spaced apart to be the same distance as the length of the interstrips. The cutting device does not cut or cause indentation on the support layer. In some embodiments, the system further comprises a pair of rollers which have one or more slots (or notches) on atleast one of the rollers. The precut Li layer on the support layer and a collector foil is fed into the pair of rollers. As described above, one or both of the rollers (41,42) may have one or more slots that enable the intermittent lamination of Li strips to the collector foil while the interstrips remain on the support layer(s). In some embodiments, the system comprises a peeling device, for example, a roll winding device that collects collector foil (24) with the Li strips laminated thereto while removing the support layer along with the interstrips from collector foil (24). In some embodiments, the roll winding device rolls the support layer with the Li interstrips into a roll and simultaneously peels the Li strips from the support layer, thereby forming a Li composite foil (61 / 62) with the Li strips attached to the collector foil (24).

[0039] In some embodiments, the cutting device comprises two blades in parallel. In some embodiments, each of the multiple Li strips has a length of LI. In some embodiments, each of the interstrip has a length substantially equal to the gap between adjacent Li strips.

[0040] In some embodiments, each of the multiple Li strips has a length of LI. In some embodiments, each of the interstrip has a length of L2. In some embodiments, the slot fitting one of the interstrips has an arc length of L2. In some embodiments, the gap between adjacent lithium strip has a length of L2. Thus, in some embodiments, the length of the interstrips, the arc length of the slot(s), and the length of the gap between adjacent lithium strips may all be the same, or approximately, the same length (L2). In some embodiments, LI is greater than L2.

[0041] In some embodiments, the collector foil has a width greater than that of the Li layer.

[0042] In some embodiments, the method further comprises a step of laminating the lithium composite foil with another support layer.

[0043] In some embodiments, each of the first and second rollers has one or more slots, and when there are multiple slots, they are evenly distributed along the periphery of the first or second roller.

[0044] In some embodiments, the cutting device applies to the Li layer a cutting force, which is smaller than the minimum peeling force to peel the multiple Li strips from the support layer.

[0045] In some embodiments, the strips are peeled from the support layer with a peeling force higher than the minimum peeling force to peel the multiple Li strips from the support layer and lower than the minimum peeling force to peel the Li strips from the collector foil.

[0046] In some embodiments, either the first or second roller has one or more slots.

[0047] In some embodiments, either the first or second roller is made by attaching a layer to a roller without slots or by carving the one or more slots on surface thereof.

[0048] In some embodiments, the first and second rollers have the same or different perimeter.

[0049] In one aspect, the present disclosure provides a method of preparing a lithium composite foil in which multiple first Li strips are on one side of a collector foil and a multiple second Li strips are on the other side of the collector foil. In some embodiments, each of the multiple first and second Li strips has a length of LI and with a gap of L2 between adjacent Li strips.

[0050] In one aspect, as shown in Fig. 6B, the present disclosure provides a system of preparing a lithium composite foil comprising multiple first Li strips on one side of a collector foil and multiple second Li strip on the other side of the collector foil. In some embodiments, the system comprises: 1) a first cutting device which can precut a first continuous Li layer on a first support layer into a first precut Li foil comprising multiple first Li strips and multiple first Li interstrips on the first support layer, and 2) a second cutting device which can precut a second continuous Li layer on a second support layer into a second precut Li foil comprising multiple second Li strips and multiple second Li interstrips on the second support layer. The cutting devices do not cut or cause indentation on the first or second support layer. In some embodiments, the system further comprises a pair of rollers which have one or more slots (or notches) on at least one of the rollers. The precut first and second Li layers with the support layers and a collector foil such as Cu foil are fed into the pair of rollers. When the rollers roll against each other, each of the Li interstrips fits into one of the slots, remains on the corresponding support layer and is not bonded to the collector foil. The first and second Li strips are compounded to the collector foil by a compression force generated by the rollers. In some embodiments, the systemcomprises a peeling device, for example, a roll winding device for rolling up each support layer. Simultaneously, the first and second Li strips are peeled from the corresponding support layer and compounded to the collector foil, thereby forming a lithium composite foil (62). In some embodiments, one of the multiple first Li strips is aligned with one of the multiple second Li strips.

[0051] In some embodiments, each of the first and second cutting devices comprises two blades in parallel. In some embodiments, each of the Li interstrips has a length substantially equal to the length of the slot into which the lithium interstrip fits.

[0052] In some embodiments, the method comprises: a) providing a first Li foil comprising a first continuous Li layer on a first support layer and a second Li foil comprising a second continuous Li layer on a second support layer; b) cutting the first continuous Li layer of the first Li foil, using a first cutting device, into a first precut Li foil comprising multiple first Li strips and multiple first Li interstrips on the first support layer; c) cutting the second continuous Li layer of the second Li foil, using a second cutting device, into a second precut Li foil comprising multiple second Li strips each with a length equal to the multiple first Li strips; and multiple second Li interstrips each with a length equal to the multiple first Li interstrips; d) via a rolling system comprising a first roller and second roller rolling against each other, at least one of the first and second rollers comprising a slot with an arc length substantially equal to the length of one of the first interstrips, the slot facing one of the multiple Li interstrips when they meet, laminating the multiple first Li strips on the first support layer to one side of a collector foil and the multiple second Li strips on the second support layer to the other side of the collector foil, while the multiplefirst and second interstrips remain on the first and second support films, respectively, and not bonded to the collector foil; and e) peeling the multiple first and second Li strips, via a first and second peeling device, from the first and second support layers, respectively, leading to a lithium composite foil in which the multiple first Li strips are on one side of the collector foil and the multiple second Li strips are on the other side of the collector foil.

[0053] In some embodiments, each of the multiple first and second Li strips has a length of LI and with a gap of L2 between adjacent Li strips.

[0054] In some embodiments, the first continuous Li layer has a thickness or width same as or different from that of the second continuous Li layer. In some embodiments, each of the first and second continuous Li layers independently has a thickness in a range from 5 pm to 100 pm, from 5 pm to 50 pm, from 5 pm to 40 pm, from 5 pm to 30 pm, from 5 pm to 20 pm, from 10 pm to 100 pm, from 10 pm to 50 pm, from 10 pm to 40 pm, from 10 pm to 30 pm, from 10 pm to 20 pm, from 15 pm to 100 pm, from 15 pm to 50 pm, from 15 pm to 40 pm, from 15 pm to 30 pm, or all and any ranges and subranges therebetween. In some embodiments, each of the first and second continuous Li layers independently has a width in a range from 40 mm to 500 mm, from 40 mm to 300 mm, from 40 mm to 200 mm, from 40 mm to 100 mm, from 60 mm to 500 mm, from 60 mm to 300 mm, from 60 mm to 200 mm, from 60 mm to 100 mm, from 75 mm to 500 mm, from 75 mm to 300 mm, from 75 mm to 200 mm, from 75 mm to 100 mm, or all and any ranges and subranges therebetween.

[0055] In some embodiments, each of the first and second support layers has a width greater than that of the first and second continuous Li layers. In some embodiments, each of the first and second support layers independently has a width a range from 50 mm to 350 mm, from 50 mm to 300 mm, from 50 mm to 250 mm, from 50 mm to 200 mm, from 50 mm to 150 mm, from 50 mm to 100 mm, from 75 mm to 350 mm, from 75 mm to 300 mm, from 75 mm to 250 mm, from 75 mm to 200 mm, from 75 mm to 150 mm, from 75 mm to 100 mm, from 100 mmto 350 mm, from 100 mm to 300 mm, from 100 mm to 250 mm, from 100 mm to 200 mm, from 100 mm to 150 mm, or all and any ranges and subranges therebetween.

[0056] In some embodiments, the collector foil such as Cu foil has a width greater than that of the first and second continuous Li layers. In some embodiments, the collector foil has a thickness in a range from 2 gm to 50 gm, from 2 gm to 40 gm, from 2 gm to 30 gm, from 2 gm to 20 gm, from 2 gm to 10 gm, from 2 gm to 7.5 gm, from 5 gm to 50 gm, from 5 gm to 40 gm, from 5 gm to 30 gm, from 5 gm to 20 gm, from 5 gm to 10 gm, from 5 gm to 7.5 gm, from 7.5 gm to 50 gm, from 7.5 gm to 40 gm, from 7.5 gm to 30 gm, from 7.5 gm to 20 gm, from 7.5 gm to 10 gm, from 10 gm to 50 gm, from 10 gm to 40 gm, from 10 gm to 30 gm, from 10 gm to 20 gm, or all and any ranges and subranges therebetween.

[0057] In some embodiments, each of the first and second support films comprises a polymer selected from the group consisting of polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), perfluoroalkoxy (PF A), polyvinyl chloride (PVC) and polyimide (PI).

[0058] In some embodiments, the method further comprises a step of laminating the lithium composite foil with a third support layer. The third support layer is to separate lithium composite foil. In some embodiments, the first cutting device applies to the continuous Li layer a first cutting force lower than the minimum peeling force to peel the first strips from the first support layer. In some embodiments, the second cutting device applies to the continuous Li layer a second cutting force lower than the minimum peeling force to peel the second strips from the second support layer.

[0059] In some embodiments, the multiple first strips are peeled from the first support layer with a first peeling force higher than the minimum peeling force to peel the first Li strips from the first support layer and lower than the minimum peeling force to peel the first Li strips from the collector foil. In some embodiments, the second strips are peeled from the second support film with a second peeling force higher than the minimum peeling force to peel the second Li strips from the second support later and lower than the minimum peeling force to peel thesecond Li strips from the collector foil. In some embodiments, each of the first and second rollers has one or more slots, and when there are multiple slots, they are evenly distributed along the periphery of the first or second roller.

[0060] In some embodiments, the first cutting device does not cut, destroy, or cause indentation on the first support layer. In some embodiments, the second cutting device does not cut, destroy, or cause indentation on the second support layer.

[0061] In some embodiments, either the first or second roller is made by attaching a layer to a roller without slots or by carving the one or more slots on surface thereof.

[0062] In some embodiments, all the steps above are conducted in an inert atmosphere.

[0063] In some embodiments, the multiple Li strips are strongly adhered or bonded to the collector foil. In some embodiments, the adhesive strength (alternatively peeling strength) between the lithium strip and collector foil is measured by a tape test. In some embodiments, the adhesive strength can be measured using an analyzer according to ASTM D3330 at a peeling angle of 180°. Typically, one end of a composite strip comprising a lithium strip on at least one side of Cu foil is adhered to a rigid panel via a double-sided tape, so that Li strip is strongly adhered to the rigid panel. The rigid panel is mounted to a fixed grip of a universal tensile testing machine. The other end of the composite strip is a loose end and is inserted into a grip on a moveable crosshead. The collector layer (e.g., Cu foil) is peeled from the Li strip adhered to the rigid panel at 180 degrees while the crosshead moves at a constant speed of 50- 600 mm / min or other speeds suitable for peeling tests. The adhesive strength (peeling strength) is an average force divided by the width of the double-sided tape. In some embodiments, the double-sided tape has a width smaller than that of the lithium strip. In one embodiment, the double-sided tape has a width of 45 mm. In some embodiments, the peeling length is 50 mm or greater.

[0064] In some embodiments, the peeling test can be measured in N / m. In some embodiments, the adhesive strength between the two layers, e.g., Li strip and current foil such as copper foil,is, for example, at least 500 N / m. In some embodiments, the adhesive strength is at least 600N / m, at least 700 N / m, at least 800 N / m, at least 900 N / m, at least 1000 N / m, at least 1100 N / m, at least 1200 N / m, at least 1300 N / m, at least 1400 N / m, at least 1500 N / m, at least 1600 N / m, at least 1700 N / m, at least 1800 N / m, at least 1900 N / m, or at least 2000 N / m.

[0065] In some embodiments, the anode exhibits an area capacity of at least 4.0 mAh / cm2, at least 4.2 mAh / cm2or at least 4.5 mAh / cm2. In some embodiments, an electrochemical device comprising the anode exhibits a discharge capacity of around 190 mAh / g at a discharge rate of 0.33C. In some embodiments, an electrochemical device comprising the anode exhibits an average coulombic efficiency (CE) of at least 80%, at least 82.0 % at least 85.0%, at least 87.0% or at least 90.0% for the first 100 cycles. In some embodiments, an electrochemical device is a coin cell or a pouch cell.ExamplesExample 1

[0066] In this example, a lithium composite foil with multiple first Li strips on one side of the collector foil and multiple second Li strips on the other side of the collector foil was prepared by following the steps below:1) having a first Li foil comprising a first continuous Li layer on PET film as first support layer and a second Li foil comprising a second continuous Li layer on PET film as second support layer;2) the first continuous Li layer of the first Li foil was cut by a first cutting device into a first precut Li foil comprising multiple first Li strips and multiple first Li interstrips on the first support layer;3) the second continuous Li layer of the second Li foil was cut by a second cutting device into a second precut Li foil comprising multiple second Li strips and multiple second Li interstrips on the second support layer, wherein each second Li strip has a length equal to the multiple first Li strips;4) the multiple first Li strips on the first support layer were laminated to one side of a Cu foil as collector foil (thickness around 10 pm) while the multiple second Li strips on the second support layer were laminated to the other side of the Cu foil, via a rolling system comprising a first roller and second roller rolling against each other, at least one of the first and second rollers comprising a slot with an arc length substantially equal to the length of one of the first interstrips, the slot facing one of the multiple Li interstrips when they meet, while the multiple first and second interstrips remain on the first and second support films, respectively, and not bonded to the Cu foil; and5) the multiple first and second Li strips were peeled from the first and second support layers, respectively, via a first and second peeling device, leading to a lithium composite foil of example 1, wherein the multiple first Li strips are on one side of the Cu foil and the multiple second Li strips are on the other side of the Cu foil.

[0067] The multiple first Li strips of the lithium composite foil had a length of 520 ± 1 mm. The multiple second Li strips had a length of 520 ± 1 mm. The gap between adjacent first Li strips had a distance of 30 ± 1 mm. The total thickness was 51.8 ± 2.2 pm. The Li strip on each side of the Cu foil was around 20 pm. The lithium composite foil of the present disclosure exhibited a bulk resistivity (volume resistivity) comparable to that of others. The anode areal capacity was 4.46 ± 0.04 mAh / cm2.

[0068] In some embodiments, the multiple first Li strips on one side of the collector foil were aligned with the multiple second Li strips on the other side of the collector foil. The alignment was measured by an optical measuring machine (OMM). In some embodiments, one edge of a first Li strip along a length direction was within 0 ± 0.5 mm of that of a second Li strip. In some embodiments, the other edge of the multiple first Li strips along the length direction of the Li strip was within 0 ± 1.5 mm of that of the multiple second Li strip.

[0069] The adhesive strength between the lithium strip and collector foil was measured by a peeling test according to ASTM D3330 at a peeling angle of 180° on a universal tensile machine.One end of a composite strip was adhered to a rigid panel via a double-sided tape with a precut shape so that Li strip was adhered to the rigid panel, one end of which is clamped by a grip mounted to the bottom of the universal tensile machine. The other end of the composite strip was a loose end and was inserted into another grip on a moveable crosshead. The collector layer (e.g., Cu foil) was peeled at 180 degrees from the Li strip adhered to the rigid panel via the double-sided tape, while the crosshead moved at a constant speed of 60 mm / min. The adhesive strength between Li strip and collector foil was an average force divided by the width of the tape. The peeling distance was around 50 mm. The adhesive strength was found to be at least 600 N / m since the adhesive failed to separate Li strip from Cu foil. The adhesive strength was unexpectedly higher than other commercially available products.

[0070] A pouch cell (0.75 Ah) with example 1 as the anode was assembled and was tested. The pouch cell exhibited a discharge capacity of around 190 mAh / g at a charge and discharge rate of 0.33 / 0.33C. The discharge capacity was substantially the same as the commercially available anode. In some embodiments, the pouch cell exhibited an average coulombic efficiency (CE) of around 84% for the first 100 cycles.Aspects

[0071] In a first aspect, the present disclosure provides a method of preparing a lithium (Li) composite foil. The method comprises: a) feeding a Li foil comprising a Li layer on a support layer, to a cutting device; b) cutting the Li layer on the support layer with the cutting device into a precut Li foil comprising multiple Li strips and multiple Li interstrips on the support layer; c) feeding the precut Li foil and a collector foil through a rolling system comprising a first roller and an opposing second roller to laminate the multiple Li strips to the collector foil, wherein at least one of the first and second rollers comprises a slot such that the slot is aligned with the multiple Li interstrips such that the multiple Li interstrips are not laminated to the collector foil; andd) removing the multiple Li strips from the support layer, leading to a Li composite foil in which the multiple Li strips are on one side of the collector foil.

[0072] In a second aspect according to the first aspect, the cutting device comprises two blades in parallel. In some embodiments, each of the multiple Li strips has a length of LI and each of the multiple Li interstrips has a length of L2. In some embodiments, the slot has an arc length substantially equal to that of a gap between adjacent Li strips.

[0073] In a third aspect according to the first or second aspect, the collector foil is made of a material selected from the group consisting of Cu, stainless steel, Ti, Ni, Ta, Mo, Nb, Sn, Zn, Ag, Au, Cu-Ni alloy, Cu-Zn alloy, Ni-Cr alloy, phosphor bronze and a combination thereof.

[0074] In a fourth aspect according to any preceding aspect, the Li layer is made of lithium metal or an alloy of lithium metal with at least one selected from the group consisting of C, Si, Sn, Ge, B, Al, In, Bi, Sb, Na, Mg, Zn, Au, and Ag.

[0075] In a fifth aspect according to any preceding aspect, the Li layer has a thickness in a range from 5 pm to 50 pm and a width in a range from 40 mm to 300 mm. In some embodiments, the support layer has a width in a range from 50 mm to 350 mm.

[0076] In a sixth aspect according to any preceding aspect, the support layer is made of a polymer selected from the group consisting of polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), perfluoroalkoxy (PF A), polyvinyl chloride (PVC), polyimide (PI) and has a width equal to or greater than that of the Li layer.

[0077] In some embodiments, collector foil has a width in a range from 50 mm to 350 mm and a thickness in a range from 2 pm to 20 pm. In some embodiments, the collector foil has a width equal to or greater than that of the continuous Li layer.

[0078] In a seventh aspect according to any preceding aspect, the method may further comprise a step of laminating the Li composite foil with a support film.

[0079] In an eighth aspect according to any preceding aspect, the at least one of the first and second rollers comprises multiple slots and the slots are evenly distributed along the peripheryof the first or second roller. In some embodiments, each of the first and second rollers comprises the slot.

[0080] In a nineth aspect according to any preceding aspect, the multiple Li strips are removed from the support layer with a peeling force higher than the minimum peeling force to peel the multiple Li strips from the support layer and lower than the minimum peeling force to peel the Li strips from the collector foil.

[0081] In a tenth aspect according to any preceding aspect, the Li composite foil exhibits an adhesive strength of at least 600 N / m between Li strip and the collector foil.

[0082] In some embodiments, the cutting device does not cause indentation on the support layer. In some embodiments, the Li foil is continuously fed to the cutting device.

[0083] In an eleventh aspect, the present disclosure provides a method of preparing a lithium (Li) composite foil. The method comprises: a) feeding a first Li foil comprising a first Li layer on a first support layer and a second Li foil comprising a second Li layer on a second support layer to first and second cutting devices, respectively; b) cutting the first Li layer on the first support layer, using the first -cutting device, into a first precut Li foil comprising multiple first Li strips and multiple first Li interstrips on the first support layer; c) cutting the second Li layer on the second support layer, using the second cutting device, into a second precut Li foil comprising multiple second Li strips and multiple second Li interstrips on the second support layer; d) feeding the first precut Li foil, the second precut Li foil and a collector foil through a rolling system comprising a first roller and an opposing second roller to laminate the multiple first Li strips to a first surface of the collector foil and the multiple second Li strips to a second surface of the collector foil, wherein each of the first and second rollers comprises a slot such that the slot is aligned with the multiple first and secondLi interstrips such that the multiple first and second Li interstrips are not laminated to the collector foil; and e) removing the multiple first and second Li strips from the first and second support layers, respectively, leading to a Li composite foil in which the multiple first Li strips are on the first surface of the collector foil and the multiple second Li strips are on the second surface of the collector foil.

[0084] In some embodiments, each of the first and second cutting devices comprises two blades in parallel. In some embodiments, each of the multiple first and second Li strips has the same length, and each of the multiple first and second Li interstrips has the same length. In some embodiments, the slot has an arc length substantially equal to that of a gap between adjacent first or second Li strips. In some embodiments, the Li composite foil exhibits an adhesive strength of at least 600 N / m between each of the multiple Li strips and the collector foil.

[0085] In a twelfth aspect according to the eleventh aspect, the collector foil is made of a material selected from the group consisting of Cu, stainless steel, Ti, Ni, Ta, Mo, Nb, Sn, Zn, Ag, Au, Cu-Ni alloy, Cu-Zn alloy, Ni-Cr alloy, phosphor bronze and a combination thereof.

[0086] In some embodiments, the first and second Li layer is made of lithium metal or an alloy of lithium metal with at least one selected from the group consisting of C, Si, Sn, Ge, B, Al, In, Bi, Sb, Na, Mg, Zn, Au, and Ag. In some embodiments, each of the first and second Li layers has a thickness in a range from 5 pm to 50 pm and a width in a range from 40 mm to 300 mm. In some embodiments, the first Li layer has a thickness or width same as or different from that of the second Li layer. In some embodiments, each of the first and second support layers has a width in a range from 50 mm to 350 mm. In some embodiments, wherein each of the first and second support layers has a width equal to or greater than that of the first and second Li layers. In some embodiments, the collector foil has a width in a range from 50 mm to 350 mm and a thickness in a range from 2 pm to 20 pm. In some embodiments, the collector foil has a width greater than that of the first and second Li layers. In some embodiments, each of the first andsecond support layers is made of a polymer selected from the group consisting of polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), perfluoroalkoxy (PF A), polyvinyl chloride (PVC), polyimide (PI).

[0087] In some embodiments, the method further comprises a step of laminating the Li composite foil with a third support layer.

[0088] In a thirteenth aspect according to the eleventh or twelfth aspect, the multiple first Li strips are removed from the first support layer with a first peeling force higher than the minimum peeling force to peel the multiple first Li strips from the first support layer and lower than the minimum peeling force to peel the multiple first Li strips from the collector foil. In some embodiments, the multiple second strips are removed from the second support layer with a second peeling force higher than the minimum peeling force to peel the multiple second Li strips from the second support layer and lower than the minimum peeling force to peel the multiple second Li strips from the collector foil.

[0089] In a fourteenth aspect, each of the first and second rollers has multiple slots that are evenly distributed along the periphery of the first or second roller.

[0090] In some embodiments, the first device does not cut or cause indentation on the first support layer. In some embodiments, the second cutting device does not cut or cause indentation on the second support layer.

[0091] In a fifteenth aspect, the present disclosure provides a lithium (Li) composite foil prepared according to the method of any preceding aspects.

[0092] Various embodiments of the features of this disclosure are described herein. However, it should be understood that such embodiments are provided merely by way of example, and numerous variations, changes, and substitutions can occur to those skilled in the art without departing from the scope of this disclosure. It should also be understood that various alternatives to the specific embodiments described herein are also within the scope of this disclosure.

Claims

What is claimed is:

1. A method of preparing a lithium (Li) composite foil, comprising a) feeding a Li foil comprising a Li layer on a support layer, to a cutting device; b) cutting the Li layer of the Li foil with the cutting device into a precut Li foil comprising multiple Li strips and multiple Li interstrips on the support layer; c) feeding the precut Li foil and a collector foil through a rolling system comprising a first roller and an opposing second roller to laminate the multiple Li strips to the collector foil, wherein at least one of the first and second rollers comprises a slot such that the slot is aligned with the multiple Li interstrips such that the multiple Li interstrips are not laminated to the collector foil; and d) removing the multiple Li strips from the support layer, leading to a Li composite foil in which the multiple Li strips are on one side of the collector foil.

2. The method of claim 1, wherein the cutting device comprises two blades in parallel.

3. The method of claim 1 or 2, wherein the collector foil is made of a material selected from the group consisting of Cu, stainless steel, Ti, Ni, Ta, Mo, Nb, Sn, Zn, Ag, Au, Cu-Ni alloy, Cu-Zn alloy, Ni-Cr alloy, phosphor bronze and a combination thereof.

4. The method of any preceding claim, wherein the Li layer is made of lithium metal or an alloy of lithium metal with at least one selected from the group consisting of C, Si, Sn, Ge, B, Al, In, Bi, Sb, Na, Mg, Zn, Au, and Ag.

5. The method of any preceding claim, wherein the Li layer has a thickness in a range from 5 pm to 50 pm and a width in a range from 40 mm to 300 mm.

6. The method of any preceding claim, wherein the support layer is made of a polymer selected from the group consisting of polyethylene terephthalate (PET), polypropylene (PP), Polyethylene (PE), perfluoroalkoxy (PF A), Polyvinyl chloride (PVC), polyimide (PI) and has a width equal to or greater than that of the Li layer.

7. The method of any preceding claim, further comprising a step of laminating the Li composite foil with another support layer.

8. The method of any preceding claim, wherein the at least one of the first and second rollers comprises multiple slots and the slots are evenly distributed along the periphery of the first or second roller.

9. The method of any preceding claim, wherein the multiple Li strips are removed from the support layer with a peeling force higher than the minimum peeling force to peel the multiple Li strips from the support layer and lower than the minimum peeling force to peel the Li strips from the collector foil.

10. The method of any preceding claim, wherein the Li composite foil exhibits an adhesive strength of at least 600 N / m between each of the multiple Li strips and the collector foil.I L A method of preparing a lithium (Li) composite foil, comprising: a) feeding a first Li foil comprising a first Li layer on a first support layer and a second Li foil comprising a second Li layer on a second support layer to first and second cutting devices, respectively; b) cutting the first Li layer of the first Li foil, using the first -cutting device, into a first precut Li foil comprising multiple first Li strips and multiple first Li interstrips on thefirst support layer; c) cutting the second Li layer of the second Li foil, using the second cutting device, into a second precut Li foil comprising multiple second Li strips and multiple second Li interstrips; d) feeding the first precut Li foil, the second precut Li foil and a collector foil through a rolling system comprising a first roller and an opposing second roller to laminate the multiple first Li strips to a first surface of the collector foil and the multiple second Li strips to a second opposing surface of the collector foil, wherein each of the first and second rollers comprises a slot such that the slot is aligned with the multiple first and second Li interstrips such that the multiple first and second Li interstrips are not laminated to the collector foil; and e) removing the multiple first and second Li strips from the first and second support layers, respectively, leading to a Li composite foil in which the multiple first Li strips are on the first surface of the collector foil and the multiple second Li strips are on the second surface of the collector foil.

12. The method of claim 11, wherein the collector foil is made of a material selected from the group consisting of Cu, stainless steel, Ti, Ni, Ta, Mo, Nb, Sn, Zn, Ag, Au, Cu-Ni alloy, Cu-Zn alloy, Ni-Cr alloy, phosphor bronze and a combination thereof.

13. The method of claim 11 or 12, wherein the multiple first Li strips are removed from the first support layer with a first peeling force higher than the minimum peeling force to peel the multiple first Li strips from the first support layer and lower than the minimum peeling force to peel the multiple first Li strips from the collector foil, and wherein the multiple second strips are removed from the second support layer with a second peeling force higher than the minimum peeling force to peel the multiple second Li strips from the secondsupport layer and lower than the minimum peeling force to peel the multiple second Li strips from the collector foil.

14. The method of any of claims 11-13, wherein each of the first and second rollers has multiple slots that are evenly distributed along the periphery of the first or second roller.

15. A lithium (Li) composite foil made according to the method of any preceding claim.

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