BATTERY CELL WITH A TEMP-MEASURING CONNECTION EMBEDDED IN ITS SEPARATOR LAYER.

Abstract

A battery cell comprises a cathode electrode with a cathode active material layer and a cathode current collector. An anode electrode comprises an anode active material layer and an anode current collector. A solid electrolyte layer is arranged between the cathode active material layer and the anode active material layer. The cathode electrode and the anode electrode exchange lithium ions. A plated terminal comprises a first metal layer and a second metal layer and includes a first section located within the solid electrolyte layer and a second section extending from the solid electrolyte layer.

Description

INTRODUCTION

[0001] The present invention relates to a battery cell according to the preamble of claim 1 having a plated terminal embedded in a separator of a battery cell.

[0002] A generic battery cell is essentially described in WO 2022 / 270 140 A1.

[0003] Further state of the art can be found in DE 10 2017 216 518 A1.

[0004] Electric vehicles (EVs), such as battery electric vehicles (BEVs), hybrid vehicles, and / or fuel cell vehicles, comprise one or more electric machines and a battery system with one or more battery cells, modules, and / or packs. A power management system is used to control the charging and / or discharging of the battery system during charging and / or driving.

[0005] Battery cells comprise one or more cathode electrodes, anode electrodes, and separators. The cathode electrodes comprise a cathode active material layer (including cathode active material) disposed on a cathode current collector. The anode electrodes comprise an anode active material layer (including anode active material) disposed on an anode current collector. SUMMARY

[0006] According to the invention, a battery cell is presented which is characterized by the features of claim 1.

[0007] In other features, the cathode electrode and the plated terminal are charged to convert the first metal layer into a lithium metal alloy.

[0008] In other features, the solid electrolyte layer comprises a first solid electrolyte portion and a second solid electrolyte portion, wherein the plated terminal is embedded in the first solid electrolyte portion, and the first solid electrolyte portion and the plated terminal are embedded in the second solid electrolyte portion.

[0009] In other features, the plated terminal is compacted in the first solid electrolyte section prior to compacting the first solid electrolyte section and the plated terminal with the second solid electrolyte section, the cathode electrode, and / or the anode electrode. The plated terminal is compacted in the first solid electrolyte section prior to compacting the first solid electrolyte section and the plated terminal between the cathode electrode and the second solid electrolyte section. The first solid electrolyte section contacts the cathode electrode.

[0010] In other features, a thickness Tc of the plated terminal is in a range of 10 µm to 50 µm, the thickness T1 of the first solid electrolyte portion is in a range of 15 µm to 60 µm, and a thickness T2 of the second solid electrolyte portion is in a range of 20 µm to 70 µm. The battery cell comprises an all-solid-state battery (ASSB cell). The first metal layer and the second metal layer comprise a foil.

[0011] Further, a method for manufacturing a battery cell is described. The method includes disposing a first portion of a plated terminal comprising a first metal layer and a second metal layer in a solid electrolyte layer, with a second portion of the plated terminal extending from the solid electrolyte layer; disposing the solid electrolyte layer and the plated terminal between a cathode electrode and an anode electrode, wherein the cathode electrode and the anode electrode exchange lithium ions; and densifying the cathode electrode, the anode electrode, the solid electrolyte layer, and the plated terminal.

[0012] In other features, the method includes charging the cathode electrode relative to the plated terminal to convert the first metal layer into a lithium-metal alloy. Prior to disposing the solid electrolyte layer and the plated terminal between the cathode electrode and the anode electrode, compacting the solid electrolyte layer and the plated terminal. The solid electrolyte layer and the plated terminal are compacted at a pressure of less than 100 MPa for a duration of less than 1 minute. The cathode electrode, the anode electrode, the solid electrolyte layer, and the plated terminal are compacted at a pressure in the range of 300 to 400 MPa for a predetermined duration in the range of 1 to 10 minutes.

[0013] In other features, the first metal layer of the plated terminal is disposed in the solid electrolyte layer perpendicular to a cathode active material layer of the cathode electrode. The battery cell comprises a solid-state battery, wherein the first metal layer is selected from a group consisting of aluminum (Al), tin (Sn), indium (In), gold (Au), zinc (Zn), bismuth (Bi), and their alloys, and the second metal layer is selected from a group consisting of stainless steel, copper, nickel, iron, titanium, and their alloys.

[0014] In other features, the solid electrolyte layer includes a first solid electrolyte portion and a second solid electrolyte portion. The plated terminal is disposed in the first solid electrolyte portion, and the first solid electrolyte portion and the plated terminal are disposed in the second solid electrolyte portion.

[0015] Further areas of applicability of the present invention will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are provided for illustrative purposes only and are not intended to limit the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be more fully understood from the detailed description and the accompanying drawings, in which: Fig. 1 is a side cross-sectional view of an example of a battery cell with a plated terminal embedded in a separator layer between a pair of anode and cathode electrodes of a battery cell according to the present invention; Fig. 2 is a side cross-sectional view of an example of an anode electrode, a cathode electrode, and a separator layer comprising a plated terminal according to the present invention; Fig. 3A is a flowchart of an example of a method for embedding the plated terminal in the separator layer according to the present invention; Fig. 3B and Fig. 3C illustrates an example of an activation method of a first metal layer of the plated terminal according to the present invention; Fig. 4A to 4C are cross-sectional views of an example of plated terminals embedded in a solid electrolyte layer according to the present invention; Fig. 5 is a side view of an example of a press including tools configured to compact a cathode electrode, an anode electrode, and a separator layer comprising a plated terminal according to the present invention; Fig. 6A and Fig. 6B are plan views showing an example of pouch battery cells with flexible plated foil and / or a rigid plated terminal extending from a pouch housing according to the present invention; Fig. 7A and Fig. 7B are diagrams illustrating an example of voltage as a function of capacity during charging and discharging according to the present invention; and Fig. 8A to 8C are diagrams showing an example of impedance for a charged state, a discharged state, and an intermediate state between the charged state and the discharged state according to the present invention.

[0017] Reference symbols may be reused in the drawings to identify similar and / or identical elements. DETAILED DESCRIPTION

[0018] Although the battery cells according to the present invention are shown in the context of electric vehicles and / or the testing of battery cells for electric vehicles, the battery cells may be used in stationary applications and / or other applications.

[0019] In the development of solid-state batteries (ASSBs), the voltage potential and / or impedance contribution of the anode and cathode electrodes are important for the design of the ASSB. It is not possible to independently monitor the voltage potential and / or impedance contribution of the cathode and anode electrodes with the existing connections at the battery terminals. It is important to characterize the performance of the anode and cathode electrodes separately and simultaneously during the cycling of the ASSB battery cells.

[0020] An in-situ monitoring device according to the present invention comprises a plated terminal, such as a plated foil, as a reference electrode in a separator layer (e.g., a solid electrolyte layer) of an all-solid-state battery (ASSB). The plated terminal comprises a first metal layer (e.g., an aluminum layer) and a second metal layer. The plated terminal is in-situ lithiated to convert the first metal layer into a lithium-metal alloy (e.g., a lithium-aluminum alloy) through a first electrochemical reaction between the cathode electrode and the first metal layer.

[0021] In some examples, the lithium metal alloy of the first metal layer exhibits low reactivity with a solid electrolyte (e.g., a sulfide solid electrolyte) and a flat potential platform (0.38 V) within the all-solid-state battery. The lithium metal alloy of the first metal layer serves as a reference electrode. Furthermore, the second metal layer (e.g., a copper layer) of the plated terminal provides high electronic conductivity as a current supply. The plated terminal can be used to monitor the voltage potential and / or impedance in-situ during operation of the ASSB.

[0022] It should be noted that the plated terminal may be used for test battery cells and / or production battery cells to enable monitoring during testing and / or during operation in a vehicle. While the example battery cells listed below include a battery cell with a single plated terminal, one or more additional plated terminals may be used within the battery cell to monitor other pairs of anode electrodes or cathode electrodes.

[0023] With reference now to Fig. 1, a battery cell 10 comprises C cathode electrodes 20, A anode electrodes 40, and S separators 32 arranged in a predetermined order in a battery cell stack 12, where C, S, and A are integers greater than zero. The C cathode electrodes 20-1, 20-2, ..., and 20-C comprise cathode active material layers 24 arranged on one or both sides of a cathode current collector 26.

[0024] During charging / discharging, the A anode electrodes 40 and the C cathode electrodes 20 exchange lithium ions. The A anode electrodes 40-1, 40-2, ..., and 40-A include anode active material layers 42 disposed on one or both sides of the anode current collectors 46. In some examples, the cathode active material layers 24 and / or the anode active material layers 42 include coatings with one or more active materials, one or more conductive additives, and / or one or more binders applied to the current collectors (e.g., by a wet or dry roll-to-roll process). In some examples, the anode and cathode electrode pairs with the separator, including the plated terminals, are manufactured in a separate process and inserted into the battery cell stack.

[0025] In some examples, the cathode current collector 26 and / or the anode current collector 46 comprise / comprise metal foil, metal mesh, perforated metal, three-dimensional (3D) metal foam, and / or expanded metal. In some examples, the current collectors are made of one or more materials selected from the group consisting of copper, stainless steel, brass, bronze, zinc, aluminum, and / or their alloys. The outer tabs 28 and 48 are connected to the current collectors of the cathode electrodes and the anode electrodes, respectively, and can be disposed on the same or different sides of the battery cell stack 12. The outer tabs 28 and 48 are connected to the terminals of the battery cells. At least one of the separators 32 includes a plated terminal 150, as described further below.

[0026] With reference now to Fig. 2, the cathode active material layer 24 comprises cathode active material 120, a conductive additive 122, and / or a solid electrolyte 124. The anode active material layer 42 comprises an anode active material 142, a conductive additive 144, and a solid electrolyte 146. The separator 32 comprises a solid electrolyte layer 130 with a plated terminal 150. A first portion of the plated terminal is embedded in the separator 32, and a second portion protrudes from the separator 32. The plated terminal includes a first metal layer 152 connected to a second metal layer 154. In some examples, the plated terminal 150 includes a wire, a thin film, a foil, and a mesh.

[0027] In some examples, the first metal layer 152 is selected from a group consisting of aluminum (Al), tin (Sn), indium (In), gold (Au), zinc (Zn), bismuth (Bi), and alloys thereof. In some examples, the first metal layer 152 (opposite or perpendicular to the cathode electrode) forms a lithium metal alloy (Li-M) that has low reactivity with the sulfide electrolyte and a stable chemical potential of the lithium alloy within the battery cell. The metal may, for example, comprise aluminum (Al), and the Li-Al alloy may be Li x Al (where 0 < x ≤ 0.8). The Li-Al alloy exhibits a stable potential platform at 0.38 V compared to Li / Li+. Other metals exhibit different potentials compared to Li / Li+. Li x For example, Sn has a potential of 0.660 compared to Li / Li+ (where 0.4 ≤ x ≤ 0.7). For example, Li x In a potential of 0.62 compared to Li / Li+. Li xAu, for example, has a potential of 0.1 compared to Li / Li+. For example, Li x Zn has a potential of 0.256 compared to Li / Li+ (where 0.4 ≤ x ≤ 0.5). For example, Li x Bi has a potential of 0.828 versus Li / Li+ (where 0 < x ≤ 1).

[0028] In some examples, the lithium capacity of the Li-M alloy is relatively low (<1µAh). In other words, the plated terminal 150 can be used for thousands of cycles. The Li-M alloy can lead to moderate volume expansion of the first metal layer 152, which has minimal impact on the solid electrolyte layer. The plated terminal 150 exhibits high mechanical stability without deformation under high pressure.

[0029] The second metal layer 154 (opposite or perpendicular to the anode electrode) provides high electronic conductivity, ensuring accurate potential monitoring. In some examples, the second metal layer 154 has a thickness in a range of 2 µm to 20 µm. In some examples, the second metal layer 154 is selected from a group consisting of stainless steel, copper, nickel, iron, titanium, and their alloys.

[0030] In some examples, the cathode active material comprises 120 LiNi x Mn y Co 1-x-y O2 (NMC), the conductive additive 122 comprises SuperP, and the solid electrolyte 124 comprises the argyrodite-type solid electrolyte Li6PSsCl (LPSCl). In some examples, the anode active material 142 comprises silicon, the conductive additive 144 comprises SuperP, and the solid electrolyte 146 comprises LPSCl.

[0031] With reference now to Fig. 3A, a method of manufacturing the battery cell includes embedding and compacting a plated terminal (including the first metal layer and the second metal layer) in a solid electrolyte at 210. In some examples, the plated terminal is embedded in the solid electrolyte and compacted by pressing the solid electrolyte and the plated terminal together at a pressure of less than 100 MPa for a period of less than 1 minute. This preliminary compaction step may serve to immobilize the plated terminal within the solid electrolyte and prevent contact with the cathode electrode or the anode electrode.

[0032] At 212, a cathode electrode, the solid electrolyte with the plated terminal, and an anode electrode are compacted. In some examples, the cathode electrode, the solid electrolyte with the plated terminal, and the anode electrode are compacted in a single compaction step or in two or more compaction steps. In some examples, the cathode electrode, the solid electrolyte with the plated terminal, and the anode electrode are compacted at a pressure in the range of 300 to 400 MPa (e.g., 360 MPa) for a predetermined duration in the range of 1 to 10 minutes (e.g., more than 2 minutes).

[0033] At 216, a lithium metal alloy is formed in situ by charging the cathode electrode (and / or the anode electrode) relative to the plated terminal 150. The plated terminal 150 can be used to monitor the voltage potential and / or impedance of the anode electrode, the cathode electrode, and / or both the anode electrode and the cathode electrode during operation at different charge or discharge states.

[0034] With reference now to Fig. 3B, in some examples, the Li-M alloy is formed in-situ by charging the cathode electrode 20 with respect to the plated terminal 150 with a low current (<1 µA, <1 hour). In some examples, the in-situ forming also includes charging the anode electrode 40 with respect to the plated terminal 150 with a low current (<1 µA, <1 hour), as shown in Fig. 3C. Charging the anode electrode relative to the plated terminal can be used for a uniform Li-Al alloy in the battery, allowing the impedance and potential of the anode / plating foil to be tested more accurately. If the battery (cathode electrode versus anode electrode) has a SOC greater than zero percent, there is some active lithium in the anode electrode, and the plated foil can form the Li-Al alloy in situ.

[0035] When activating the plated terminal 150, the cathode electrode 20 is connected as a positive terminal and the plated terminal 150 as a negative terminal to a charger, as shown in Fig. 3B. The cathode electrode 20 and the plated terminal 150 are charged with a current (<1 µA) to a stable voltage when the lithium alloy has been formed. The current (<1 µA) is very low and the capacity loss of the cathode electrode is minimal, so the chemical potential of the cathode electrode is stable. The potential of Al is stable when a Li-Al alloy is formed. The charging voltage of the cathode electrode and the plated terminal is equal to the chemical potential of the cathode minus the potential of the Li-Al alloy. The charging time is less than 0.5 hours.

[0036] In some examples, the anode electrode 40 is connected to the charger as a positive terminal and the plated terminal 150 as a negative terminal, as shown in Fig. 3C. The anode electrode 20 and the plated terminal 150 are charged with a current (e.g., <1 µA) for a predetermined duration (e.g., <0.5 hours). The Li-M alloy is activated, and the plated terminal 150 can be used for potential monitoring. If the reference potential is not monitoring the solid-state battery, the charging protocol described above is repeated.

[0037] With reference now to Fig. 4A to 4C show examples of the compaction of the plated terminal 150 in a solid electrolyte layer. In Fig. 4A, the plated terminal 150 is compacted near a central region of a solid electrolyte layer 300 (e.g., such that the plated terminal 150 is spaced from a cathode electrode 304 and anode electrode 306 to avoid short circuits). Then, the plated terminal 150 and the solid electrolyte layer 173 are compacted with the cathode electrode 304 and the anode electrode 306. Alternatively, the plated terminal 150 and the solid electrolyte layer 300 are compacted with the cathode electrode 304 and the anode electrode 306 in a single compaction step.

[0038] In Fig. 4B, the plated terminal 150 is densified near a central region of a first solid electrolyte layer 320 (e.g., spaced apart from the cathode electrode 304 and the anode electrode 306). Then, the plated terminal 150 and the first solid electrolyte layer 320 are embedded in a second solid electrolyte layer 324 near a central region of the second solid electrolyte layer 324 (e.g., spaced apart from the cathode electrode 304 and the anode electrode 306).

[0039] In some examples, the second solid electrolyte layer 324 is densified around the plated terminal 150 and the first solid electrolyte layer 320, and one or more subsequent densification steps are used to densify the cathode electrode 304 and / or the anode electrode 306 around the second solid electrolyte layer 324. Alternatively, the cathode electrode 304 and / or the anode electrode 306, the second solid electrolyte layer 324, as well as the plated terminal 150 and the first solid electrolyte layer 320, are densified together in a single or combined densification step. This approach may be used when the position of the plated terminal can be maintained in the center of the solid electrolyte layer (avoiding short circuits with the anode or cathode electrodes).The first solid electrolyte layer 320 may be made of the same type of solid electrolyte as the second solid electrolyte layer 324, or the first solid electrolyte layer 320 and the second solid electrolyte layer 324 may be formed of different types of solid electrolytes.

[0040] The solid electrolyte material for the first solid electrolyte layer 320 is selected to have high reduction stability and compatibility with the first metal layer 152 (e.g., the Li-M alloy). As a result, the Li-M alloy has a longer lifetime due to its low reactivity with the first solid electrolyte layer 320. The first solid electrolyte layer 320 may, for example, comprise a sulfide solid electrolyte such as Li7P3S. 11It should be noted that the plated terminal 150 and the first solid electrolyte layer 320 may be embedded in different types of solid electrolytes and / or battery cell chemistries. In some examples, a thickness T2 of the second solid electrolyte layer 324 is greater than a thickness T1 of the first solid electrolyte layer 320. In some examples, the thickness of the first solid electrolyte layer 320 is greater than the thickness T c of the plated terminal 150.

[0041] In some examples the thickness T c in a range of 10 µm to 50 µm. In some examples, the thickness T1 is in a range of 15 µm to 60 µm. In some examples, the thickness T2 is in a range of 20 µm to 70 µm.

[0042] In Fig. 4C, the plated terminal 150 is compacted in the first solid electrolyte layer 320 as described above. Then, the plated terminal 150 and the first solid electrolyte layer 320 are compacted between a cathode electrode 186 and a second solid electrolyte layer 330. The plated terminal 150 can be arranged along the cathode active material layer of the cathode electrode 304 because the first solid electrolyte 182 insulates the plated terminal 150.

[0043] With reference now to Fig. 5 shows an example of a press 350 for manufacturing a battery cell having a cathode electrode, an anode electrode, and a separator with an embedded plated terminal / foil. In some examples, a pellet cell format is used. An upper press 352 is connected to an upper tool 354, and a lower press 356 is connected to a lower tool 358. In some examples, the upper tool 354, the lower tool 358, the upper press 352, and the lower press 356 are made of stainless steel. A mold 364 includes an internal cavity 365 having a diameter slightly larger than the diameter of the battery cell and configured to receive the upper tool 354 and the lower tool 358. In some examples, the mold 364 is made of a polymer such as polyetheretherketone (PEEK) or another suitable polymer.

[0044] An anode electrode 374 (including an anode current collector and an anode active material) is disposed in the inner cavity 365 on the lower tool 358. A portion of the solid electrolyte material corresponding to a solid electrolyte layer 370 is disposed on the anode electrode 374, and the plated terminal 150 is inserted through a hole 375 in the mold 364. The remainder of the solid electrolyte material corresponding to the solid electrolyte layer 370 is disposed on the plated terminal and the remaining material of the solid electrolyte layer 370. A cathode electrode 372 (containing cathode active material and a cathode current collector) is disposed on the solid electrolyte layer 370. The press 350 applies pressure and / or heat to densify the layers.

[0045] With reference now to Fig. 6A and Fig. 6B, a pouch cell 400 includes a pouch housing 410 with a battery cell stack 412. Terminals 414 and 418 extend from the pouch housing 410 and are electrically connected to outer tabs, which are connected to anode and cathode current collectors, respectively. At least one separator includes the plated terminals 150 embedded therein. The at least one separator is disposed between a cathode electrode and an anode electrode, as described above. In Fig. 6A, the plated terminal 150 is flexible and made of foil. In Fig. 6B the plated terminal is rigid.

[0046] With reference now to Fig. 7A and Fig. 7B, the plated terminal allows voltage monitoring of the cathode electrode C, the anode electrode A, or both the anode electrode and the cathode electrode F (sum of the cathode electrode and the anode electrode). Fig. Figure 7A shows the voltage as a function of the capacity of a battery cell during charging to 4.2 V using DC / DC voltage (cc-cv) at a rate of 0.5 C. Fig. Figure 7B shows the voltage as a function of the capacity of a battery cell during charging from over 4 V to 2.5 V using DC / DC (cc) at a rate of 0.5 C and a temperature of 25 °C.

[0047] With reference now to Fig. 8A to 8C show the impedance monitoring of the cathode electrode C, the anode electrode A, or both the anode electrode and the cathode electrode F in a charged state at 4.2 V ( Fig. 8A), a discharged state at 2.6 V ( Fig. 8B), and other voltage levels such as 3.4 V ( Fig. 8C) over a frequency range from 100 kHz to 1 Hz (adjusted).

Claims

[1] Battery cell (10), comprising: a cathode electrode (20) having a cathode active material layer (24) and a cathode current collector (26); an anode electrode (40) having an anode active material layer (42) and an anode current collector (46); a solid electrolyte layer (130) disposed between the cathode active material layer (24) and the anode active material layer (42), wherein the cathode electrode (20) and the anode electrode (40) exchange lithium ions; and a plated terminal (150) comprising a first metal layer (152) and a second metal layer (154) and comprising a first portion disposed in the solid electrolyte layer (130) and a second portion extending from the solid electrolyte layer (130); wherein the first metal layer (152) of the plated terminal (150) is disposed in the solid electrolyte layer (130) and is selected from a group consisting of aluminum (Al), tin (Sn), indium (In), gold (Au), zinc (Zn), bismuth (Bi), and alloys thereof; and wherein the second metal layer (154) is selected from a group consisting of stainless steel, copper, nickel, iron, titanium and alloys thereof; characterized by , that the first metal layer (152) forms a side of the plated terminal (150) facing the cathode electrode (20), whereas the second metal layer (154) forms a side of the plated terminal (150) facing the anode electrode (40). [2] Battery cell (10) according to claim 1, wherein: the solid electrolyte layer (130) comprises a first solid electrolyte section (320) and a second solid electrolyte section (324), the plated terminal (150) is embedded in the first solid electrolyte section (320), and the first solid electrolyte portion (320) and the plated terminal (150) are embedded in the second solid electrolyte portion (324). [3] The battery cell (10) of claim 2, wherein the first solid electrolyte portion (320) contacts the cathode electrode (20). [4] Battery cell (10) according to claim 2, wherein a thickness T c of the plated terminal (150) is in a range of 10 µm to 50 µm, a thickness T1 of the first solid electrolyte portion (320) is in a range of 15 µm to 60 µm, and a thickness T2 of the second solid electrolyte portion (324) is in a range of 20 µm to 70 µm.

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