Additives for lithium-ion batteries

Abstract

A lithium-ion battery component is presented. The lithium-ion battery cell comprises a current collector and an active material layered upon it. The active material includes an active electrode material, a conductive medium, and a binder, with a solid electrolyte-containing underside adjacent to the current collector. The battery cell further includes a liquid electrolyte that permeates the active material layer, thereby enhancing ion transport through interaction with the solid electrolyte during cycling.

Description

AREA OF TECHNOLOGY

[0001] The disclosure concerns electrode additive materials for lithium-ion batteries. GENERAL STATE OF THE ART

[0002] Microscopic observations of lithium-ion battery anode cross-sections indicate that lithiation can vary along the depth of the electrode during charging and discharging. The lower layer of the anode may remain less lithiated, while the upper layer may exhibit a higher degree of lithiation. This variation in lithiation behavior can lead to differences in the local potential within the anode. SUMMARY

[0003] An electrode comprises a current collector, an active material layered onto the current collector (containing an active electrode material, a conductive agent, and a binder), and a solid electrolyte-containing underside adjacent to the current collector. A liquid electrolyte permeates the active material layer and is configured to enhance ion transport with the solid electrolyte during electrode cycling. The current collector can be copper-based. The solid electrolyte can be sulfur-based, oxygen-based, or halide-based. The solid electrolyte can constitute less than 10 wt% of the electrode. The liquid electrolyte can be carbonate-based. The active material can be graphite-based.

[0004] One method for manufacturing an electrode involves depositing a bottom layer of active electrode material, conductive medium, binder, and solid electrolyte onto a current collector; depositing an upper layer of active electrode material, conductive medium, and binder onto the bottom layer; and permeating the layers with a liquid electrolyte to facilitate ion transport with the solid electrolyte during electrode cycling. The solid electrolyte may consist of sulfides, oxides, or halides. The upper layer may be deposited using a spray coating technique. The deposited layers may be dried before permeating with the liquid electrolyte. The liquid electrolyte may be a mixture of ethylene carbonate and diethyl carbonate. The layers may be pressed together after deposition. The electrode may contain less than 10 wt% solid electrolyte.

[0005] A lithium-ion battery cell comprises a positive electrode assembly, a negative electrode assembly layered onto a current collector containing an active electrode material, a conductive medium, and a binder. The current collector has a bottom layer containing a solid electrolyte adjacent to the current collector and a liquid electrolyte permeating both electrode assemblies. The solid electrolyte is configured to increase the local presence of lithium ions in the negative electrode assembly during successive cycles of the lithium-ion battery cell. The solid electrolyte in the bottom layer of the negative electrode assembly can constitute less than 10 wt% of the lithium-ion battery cell. The solid electrolyte in the bottom layer of the negative electrode assembly can be an oxide. The solid electrolyte in the bottom layer of the negative electrode assembly can be a halide-based material. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a light microscope image of a cross-section of an anode of a lithium-ion battery; Fig. Figure 2 is a schematic representation of a lithium-ion battery cell; and Fig. Figure 3 is a flowchart of a process for manufacturing a lithium-ion battery electrode. DETAILED DESCRIPTION

[0006] Detailed embodiments of the present invention are described in this document to provide a comprehensive understanding of its implementation and operation. However, these embodiments are presented as examples and are not intended to limit the invention, which may include various alternative configurations and materials. For example, the use of solid electrolyte particles in the lower layers of the negative active material layer adjacent to the current collector, as described in this document, may include variations in the type of solid electrolyte material, such as sulfides, oxides, halides, or polymers, and their specific integration methods. The various figures included in this disclosure are schematic representations and are not necessarily to scale; features may be enlarged or reduced to highlight details of specific components.Specific constructive and functional details disclosed in this document, such as the incorporation of less than 10 wt.% solid electrolyte particles or the use of a liquid electrolyte that saturates both electrode assemblies, are not to be interpreted as restrictive, but rather as a representative basis to teach the person skilled in the art how to implement and adapt the present invention in various ways.

[0007] Unless expressly stated otherwise, all numerical values ​​and ranges provided in this disclosure—such as those relating to quantities, measurements, percentages, weights, and other numerical data—are to be interpreted as approximate. This applies even when the term “approximately” is not expressly used. For example, when a bottom layer is described as containing “less than 10 wt% solid electrolyte,” this includes minor variations due to material properties, manufacturing tolerances, or intended operation. Likewise, when a range such as “100 to 200 units” is described, it should be interpreted as “approximately 100 to approximately 200 units” to account for practical variability.These principles apply to disclosed values, such as the weight percentages of the solid electrolyte, the ratio of active materials, and the improvements in ionic conductivity achieved by using a liquid electrolyte that interacts with solid electrolyte particles. These inherent variations are considered to be within the scope of protection of the invention, as they take into account the practical realities of the manufacturing processes and material behavior described in this document.

[0008] For lithium-ion batteries in electric vehicles, the ability to quickly recharge is a factor in consumer acceptance. High-energy-density batteries, often designed with thick anode electrodes to maximize energy storage, can face challenges during fast charging. During charge and discharge cycles, the distribution of lithium ions (Li) can change. +The voltage within the anode becomes uneven, leading to incomplete lithiation of the lower layers while the upper layers achieve complete lithiation. This imbalance can create localized regions of high overvoltages in the upper layers of the anode, particularly during fast, high-current charging. Under certain conditions, these overvoltages can fall below the threshold for lithium plating, triggering lithium deposition on the electrode surface.

[0009] Quasi-solid-state batteries have been developed in which high proportions of solid-state electrolytes (SSEs) are incorporated into the active material layer of the electrode. These layers comprise an active electrode material, a conductive agent, a binder, and a composite electrolyte that can include oxide SSEs, polymer electrolytes formed via in-situ polymerization, and / or liquid electrolytes. Polymers and liquid electrolytes increase the contact between the active material and the SSE, thereby reducing impedance and improving the electrochemical properties of the electrode.

[0010] Despite these advantages, quasi-solid-state batteries are subject to limitations, particularly regarding energy density. Solid electrolytes are relatively dense materials, and their high proportion within the electrode reduces the overall energy density compared to conventional lithium-ion batteries. Additionally, the use of polymers and solid electrolytes can introduce complexities related to contact resistance and the need for precise manufacturing conditions.

[0011] The present disclosure increases the uniformity of lithiation within an anode by integrating small amounts (< 10 wt%) of solid electrolyte additives relative to the total battery cell into the lower layers of the anode electrode adjacent to the current collector. This configuration maintains stable ion transport and prevents localized overvoltage conditions. These additives, which may include sulfides, oxides, polymers, or halides, increase the local Li + -Occurrence in areas prone to ion depletion under high-current charging. This localized expansion of ion availability mitigates the effects of Li + -gradients, thereby reducing the probability of lithium plating and dendrite formation induced by overvoltage.

[0012] Each category of solid electrolyte additive can offer its own advantages. Sulfides, for example, exhibit high ionic conductivity and flexibility, which enables efficient ion transport at the interface between the additive and the anode material. Examples of sulfides include lithium thiophosphates, such as Li 10 GeP2S 12and related materials. Oxide-based solid electrolytes, such as lithium garnet or perovskite oxides, exhibit high chemical stability and heat resistance, making them suitable for long-term operation under demanding conditions. Polymer-based additives, including polyethylene oxide or cross-linked polymer matrices, increase electrode flexibility while maintaining compatibility with liquid electrolytes, effectively reducing interface impedance. Halide solid electrolytes, such as lithium chlorides or bromides, offer lower density compared to other solid electrolytes and facilitate integration with conventional liquid electrolytes while maintaining ionic conductivity. By adjusting the composition and proportion of these additives, the configurations described can maintain uniform lithiation across the entire anode.

[0013] Unlike quasi-solid-state batteries, the proposed electrode configuration does not rely on polymer electrolytes or high proportions of solid electrolytes. By maintaining the liquid electrolyte content at levels similar to those of conventional lithium-ion batteries, the proposed configuration avoids the high contact resistance problems associated with solid-state interfaces. This ensures consistent electrochemical performance of the battery.

[0014] Furthermore, the low proportion of solid electrolyte additives maintains an energy density comparable to that of conventional lithium-ion batteries. This contrasts with quasi-solid-state designs, where the high density of solid electrolyte materials can negatively impact energy density.

[0015] Fig. Figure 1 shows a light microscope cross-section of a lithium-ion battery anode during charging and discharging. The cross-section reveals an unevenness of lithiation across the depth of the anode. In particular, the lower layer of the anode adjacent to the current collector is significantly underlithiated or remains completely unlithiated. In contrast, the upper layer of the anode, closer to the separator, is fully lithiated. This uneven lithiation distribution is evident from the visible differences in material texture and color, which correlate with the degree of lithiation.

[0016] The imbalance in lithiation between the lower and upper layers of the anode can lead to electrochemical challenges. The highly lithiated upper layer of the anode can be subject to localized high overvoltages due to the uneven ion distribution. Under certain conditions, these overvoltages can fall below the potential for lithium plating, initiating lithium plating on the electrode surface. Prolonged lithium plating increases the likelihood of dendrite formation.

[0017] Fig. Figure 2 is a schematic representation of a lithium-ion battery cell 10. The lithium-ion battery cell 10 comprises a positive electrode assembly 12, a separator 14, and a negative electrode assembly 16. The positive electrode assembly 12 includes a current collector 18 and a positive active material layer 20. The current collector 18 can be a conductive metal, such as aluminum, chosen for its lightweight properties, high electrical conductivity, and compatibility with the positive active material layer 20. The positive active material layer 20 can include active materials such as lithium nickel cobalt manganese oxide, lithium iron phosphate, or lithium cobalt oxide. The positive active material layer 20 can also contain conductive materials, such as carbon black, and polymeric binders to maintain mechanical integrity and electrical connectivity.

[0018] The separator 14 is a thin, porous and electrically insulating membrane designed to prevent direct contact between them while allowing the Li + -Transports between assembly 12 of the positive electrode and assembly 16 of the negative electrode. The separator 14 can be made of polyethylene or polypropylene and may furthermore include a ceramic coating to increase thermal stability and electrolyte wettability.

[0019] The negative electrode assembly 16 comprises a negative active material layer 22 and a negative current collector 24. The negative current collector 24 can be made of copper, which provides electrical conductivity and compatibility with the negative active material layer 22. The negative active material layer 22 comprises a mixture of negative active material particles 26 and solid electrolyte particles 28, which are mainly present in the lower layers of the negative active material layer 22 near the negative current collector 24. Directing the solid electrolyte particles 28 to the vicinity of the lower layers reduces lithiation imbalances by increasing the Li+ concentration closer to the current collector 24. The negative active material particles 26 can comprise graphite, lithium titanate, or silicon-based composites. These materials serve as hosts for a Li +Intercalation and deintercalation during charging and discharging cycles. The positive and negative active material assemblies 12 and 16 may contain binder material to increase mechanical stability and adhesion between layers and between the current collector 14.

[0020] The solid electrolyte particles 28 are integrated in small quantities near the underside of the negative active material layer 22, comprising less than 10 wt% of the lithium-ion battery cell 10. The solid electrolyte particles 28 increase the local Li + -Occurrence and ionic conductivity, especially in areas prone to Li + -depletion are present. The solid electrolyte particles 28 can contain sulfides, such as Li. 10 GeP2S 12 or Li6PS5Cl, oxides such as Li7La3Zr2O 12 or perovskite oxides, polymers such as polyethylene oxide or polyacrylonitrile-based composites, or halides such as lithium chlorides or bromides.

[0021] The lithium-ion battery cell 10 can further include a liquid electrolyte 30 that saturates both the positive electrode assembly 12 and the negative electrode assembly 16. The liquid electrolyte 30 facilitates ion transport between the electrode assemblies through the separator 14 and interacts with the solid electrolyte particles 28 in the negative active material layer 22 to increase the local lithium ion concentration during cycling. The liquid electrolyte 30 can be a carbonate-based solvent, such as ethylene carbonate and diethyl carbonate, mixed with a lithium salt, such as lithium hexafluorophosphate.

[0022] Fig.Figure 3 is a flowchart of a process 32 for manufacturing a lithium-ion battery electrode. Step 34 begins with the deposition of a bottom layer, comprising active electrode material, conductive medium, binder, and solid electrolyte, onto a current collector. In step 36, an upper layer, also comprising active electrode material, conductive medium, and binder, is then deposited onto the current collector and the bottom layer. Step 36 may utilize a spray coating technique for uniformity and integration with the underlying layer. In step 38, once deposited, the layers are permeated with a liquid electrolyte to facilitate ion transport and interaction with the solid electrolyte. Prior to step 38, the layers may be dried to remove residual solvent, ensuring efficient electrolyte infiltration.Furthermore, after deposition, the layers can be subjected to compression to increase mechanical stability and contact between the materials.

[0023] Although the foregoing description provides exemplary embodiments of the invention, it is not intended to include all possible variations or configurations. The terminology used in this description serves to describe the scope of protection of the invention, rather than to limit it. It is understood that modifications and adaptations, such as variations in the type or proportion of solid electrolytes, electrode designs, or manufacturing techniques, may be made without departing from the spirit and scope of protection of the invention. Furthermore, individual features described in different embodiments may be combined or reconfigured to create additional implementations that are consistent with the principles disclosed herein.

[0024] According to the present invention, an electrode is provided comprising: a current collector; an active material layered on the current collector, comprising an active electrode material, a conductive agent and a binder, and having a bottom surface containing a solid electrolyte adjacent to the current collector; and a liquid electrolyte permeating the active material and configured to facilitate ion transport with the solid electrolyte during cycling of the electrode.

[0025] According to one embodiment, the current collector is based on copper.

[0026] According to one embodiment, the solid electrolyte is a sulfide-based material.

[0027] According to one embodiment, the solid electrolyte is an oxide-based material.

[0028] According to one embodiment, the solid electrolyte is a halide-based material.

[0029] According to one embodiment, the solid electrolyte makes up less than 10 wt.% of the electrode.

[0030] According to one embodiment, the liquid electrolyte is a carbonate-based electrolyte.

[0031] According to one embodiment, the active material is based on graphite.

[0032] According to the present invention, a method for producing an electrode comprises: depositing a lower layer of active electrode material, conductive medium, binder and solid electrolyte onto a current collector; depositing an upper layer of active electrode material, conductive medium and binder onto the lower layer; and permeating the layers with a liquid electrolyte.

[0033] According to one embodiment, the solid electrolyte contains sulfides, oxides or halides.

[0034] According to one embodiment, the upper layer is deposited using a spray coating technique.

[0035] According to one embodiment, the above invention is further characterized by drying the deposited layers before permeation.

[0036] According to one embodiment, the liquid electrolyte is a mixture of ethylene carbonate and diethyl carbonate.

[0037] According to one embodiment, the above invention is further characterized by pressing the layers together after deposition.

[0038] According to one embodiment, the electrode contains less than 10 wt% solid electrolyte.

[0039] According to the present invention, a lithium-ion battery cell is provided comprising: a positive electrode assembly; a negative electrode assembly layered onto a current collector containing an active electrode material, a conductive agent, and a binder, and having a bottom surface containing a solid electrolyte adjacent to the current collector; and a liquid electrolyte permeating both electrode assemblies and configured to increase a local occurrence of lithium ions with the solid electrolyte in the negative electrode assembly during successive cycles of the lithium-ion battery cell.

[0040] According to one embodiment, the solid electrolyte in the underside of the negative electrode assembly makes up less than 10 wt.% of the lithium-ion battery cell.

[0041] According to one embodiment, the solid electrolyte in the underside of the negative electrode assembly is an oxide-based material.

[0042] According to one embodiment, the solid electrolyte in the underside of the negative electrode assembly is a halide-based material.

Claims

[1] Electrode, comprising: a current collector; an active material layered on the current collector, containing an active electrode material, a conductive agent and a binder, and having an underside containing a solid electrolyte adjacent to the current collector; and a liquid electrolyte that permeates the active material and is configured to facilitate ion transport with the solid electrolyte during electrode cycling. [2] Electrode according to claim 1, wherein the current collector is based on copper. [3] Electrode according to claim 1, wherein the solid electrolyte is a sulfide-based material. [4] Electrode according to claim 1, wherein the solid electrolyte is an oxide-based material. [5] Electrode according to claim 1, wherein the solid electrolyte is a halide-based material. [6] Electrode according to claim 1, wherein the solid electrolyte constitutes less than 10 wt.% of the electrode. [7] Electrode according to claim 1, wherein the liquid electrolyte is a carbonate-based electrolyte. [8] Electrode according to claim 1, wherein the active material is based on graphite. [9] Electrode according to claim 1, wherein the binder is polyvinylidene fluoride. [10] Method for manufacturing an electrode, comprising: Deposition of a lower layer of active electrode material, conductive medium, binder and solid electrolyte onto a current collector; Deposition of an upper layer of active electrode material, conductive medium and binder onto the lower layer; and Permeation of the layers with a liquid electrolyte. [11] Method according to claim 10, wherein the solid electrolyte comprises sulfides, oxides or halides. [12] Lithium-ion battery cell, comprising: a component of a positive electrode; an assembly of a negative electrode layered on a current collector containing an active electrode material, a conductive medium and a binder, and having a bottom surface containing a solid electrolyte adjacent to the current collector; and a liquid electrolyte that permeates both electrode assemblies and is configured to increase a local occurrence of lithium ions with the solid electrolyte in the negative electrode assembly during successive cycles of the lithium-ion battery cell. [13] Lithium-ion battery cell according to claim 12, wherein the solid electrolyte in the underside of the negative electrode assembly constitutes less than 10 wt.% of the lithium-ion battery cell. [14] Lithium-ion battery cell according to claim 12, wherein the solid electrolyte in the underside of the negative electrode assembly is a sulfide-based material. [15] Lithium-ion battery cell according to claim 12, wherein the solid electrolyte in the underside of the negative electrode assembly is a halide-based material.

Images