Battery electrode
By forming a porous structure on the surface of the graphite electrode in a lithium-ion battery and replacing nickel nanoparticles with silver nanoparticles, the low equilibrium potential problem of the graphite anode was solved, thereby improving the fast charging performance and battery life of the lithium-ion battery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-08
- Publication Date
- 2026-03-13
AI Technical Summary
The low equilibrium potential of the graphite anode in lithium-ion batteries leads to limited overpotential tolerance, making it prone to the formation and deposition of metallic lithium under high-current charging conditions, which affects the battery's fast-charging performance and lifespan.
By forming a porous structure on the surface of a graphite-based active material and replacing nickel nanoparticles with silver nanoparticles, an electrode with increased edge surface area and porosity is formed. The silver nanoparticles form a solid solution with lithium, which improves lithium intercalation efficiency and inhibits dendrite formation.
It significantly improves the fast charging capability and electrochemical reaction kinetics of the electrodes, increases charging and discharging capacity, and improves the charge-discharge cycle efficiency and structural stability of the battery.
Smart Images
Figure CN121662764A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to electrodes used in lithium-ion batteries. Background Technology
[0002] In lithium-ion batteries, the low equilibrium potential of graphite anodes leads to limited overpotential tolerance. This can make graphite anodes prone to lithium metal formation when the potential drops below a threshold during charging, potentially leading to lithium deposition under high-current charging conditions and at higher states of charge. Various methods have been proposed to address the challenges of preventing lithium deposition and improving reaction kinetics; however, scalable methods applicable to the production of graphite electrodes for fast charging of lithium-ion batteries remain lacking. Summary of the Invention
[0003] A battery includes a positive electrode assembly and a negative electrode assembly, the negative electrode assembly having a porous matrix of graphite-based active material and lithium-loving nanoparticles occupying pores defined by the porous matrix. The lithium-loving nanoparticles may be silver nanoparticles. The lithium-loving nanoparticles may be configured to form a solid solution with lithium in the negative electrode assembly. Compared to non-porous graphite-based active materials, the porous matrix of the graphite-based active material can have an increased edge surface area. The lithium-loving nanoparticles may be in the range of 0.1 wt% to 10 wt% of the negative electrode assembly. The porous matrix may have a porosity of 10% to 50%. The lithium-loving nanoparticles may have an average diameter between 5 nm and 100 nm.
[0004] An electrode assembly includes a current collector and a graphite-based active material layer deposited on the current collector, wherein electrocatalytic nanoparticles are dispersed between the particles of the graphite-based active material layer. The graphite-based active material layer may have a porous structure. The electrocatalytic nanoparticles may be silver nanoparticles. The electrocatalytic nanoparticles may exist on the surface of the graphite-based active material and within the pores of the graphite-based active material. The graphite-based active material layer may have a thickness of 50 micrometers to 200 micrometers. The electrode assembly may be a negative electrode assembly. The current collector may be a copper foil.
[0005] A method for forming an electrode includes: loading nickel nanoparticles into a graphitic active material to form a nickel-loaded graphitic active material; hydrogenating the nickel-loaded graphitic active material to form a porous graphitic active material; and electrodisplacing the porous graphitic active material with a silver salt solution to replace the nickel nanoparticles with silver nanoparticles to form an electrode. The hydrogenation can be performed in a temperature range of 600°C to 900°C. The electrodisplacing can be performed at room temperature. The method may include controlling the radius of the silver nanoparticles by adjusting the amount of silver salt. In other configurations, the method may include depositing the formed electrode onto a current collector. Compared to a nickel-loaded graphitic active material, a porous graphitic active material can have an increased surface area. Attached Figure Description
[0006] Figure 1 This is a schematic diagram of graphite edge activation;
[0007] Figure 2 This is a schematic diagram of lithium diffusion in edge-activated graphite;
[0008] Figure 3 This is a graph showing the specific capacity and coulombic efficiency of pure graphite compared to graphite electrodes with added silver.
[0009] Figure 4 This is a schematic diagram of an electrode undergoing electro-displacement;
[0010] Figure 5 This is a schematic diagram of the reduction reaction in the electrode; and
[0011] Figure 6 This is a flowchart of a method for forming an electrode with nitrate additives. Detailed Implementation
[0012] According to this disclosure, detailed embodiments of electrode structures, manufacturing methods, and battery systems are disclosed herein. These embodiments represent innovative methods for enhancing the performance of lithium-ion batteries by modifying the surface of graphite active materials with lithiophilic and electrocatalytic nanoparticles (specifically, silver nanoparticles). The accompanying drawings and descriptions are illustrative and may not represent all possible variations or configurations. Certain features may be exaggerated or minimized to highlight specific aspects of the electrode assembly and its formation process. Therefore, the specific structural and functional details disclosed are not intended to limit the scope of the invention, but rather to provide a basis for various embodiments of the claimed subject matter to be implemented by those skilled in the art.
[0013] Unless otherwise expressly stated, all numerical values, measurements, percentages, weights, and similar quantitative parameters disclosed herein should be understood as being preceded by the term "about". This convention applies even where the term "about" is not explicitly used. The intention is to cover variations caused by standard measurement techniques, manufacturing processes, material properties, and the inherent variability in the performance of electrode structures and battery systems. For example, when referring to "10% to 50%" porosity, the range should be interpreted as "about 10% to about 50%", thus allowing for deviations in the function or performance of the electrode assembly or the overall battery system without significantly altering its overall characteristics.
[0014] This disclosure relates to a method for improving the performance of lithium-ion batteries, particularly addressing challenges associated with fast charging and battery life. This method involves modifying the surface of a graphite active material with a lithiophilic material, specifically silver nanoparticles. The method may involve a two-step process: first, forming a porous structure on the graphite surface, and second, introducing silver nanoparticles onto the modified surface.
[0015] The process begins with loading nickel nanoparticles onto a graphite surface. A hydrogenation step is then performed, inducing a porous structure by reacting nickel with carbon and hydrogen in the graphite to produce nickel and methane. This reaction increases the edge planar area, resulting in higher rate capacity and enhanced fast charging characteristics. Following this, nickel nanoparticles are replaced with silver nanoparticles via an electrodisplacement process in a silver salt solution. This displacement is driven by a difference in reduction potential, where nickel ions gain two electrons at -0.26 V to form nickel metal, while silver ions gain one electron at 0.80 V to form silver metal. The resulting silver nanoparticles can exist both on the graphite surface and within the pores created during the hydrogenation step.
[0016] Increased edge surface area and porosity facilitate easier lithium intercalation. Silver nanoparticles can form solid solutions with lithium, thereby suppressing the lithium plating process, which contributes to lithium loss and dendrite formation. Furthermore, silver nanoparticles exhibit higher electronic conductivity than conventional carbon additives, thus increasing overall electrochemical reaction kinetics. The combination of porous graphite structures and silver nanoparticles may result in increased fast-charging capabilities compared to unmodified graphite or graphite with added silver nanoparticles but without structural modification. The entire process for producing this modified graphite material is scalable, making it suitable for industrial applications. A two-step approach allows for control over the graphite structure and silver nanoparticle distribution, enabling optimization for specific battery requirements.
[0017] Figure 1 This is a schematic diagram illustrating a two-step process for modifying graphite particles to produce electrode materials. The process begins with pristine graphite, depicted as a solid black circle. In the first step, labeled "nickel loading," nickel particles are loaded onto the graphite surface, resulting in nickel-loaded graphite. The second step involves two sub-steps: step 1 involves introducing hydrogen gas, and step 2 involves adding silver. This process transforms the nickel-loaded graphite into silver-loaded graphite, where silver particles displace the nickel on the graphite surface. This modification process aims to improve the properties of graphite used as an electrode material, thereby potentially improving its performance in energy storage applications.
[0018] Figure 2The structure of edge-introduced graphite for lithium-ion battery electrodes is shown. The image shows a cross-section of the modified graphite particles. The particles retain their overall circular shape but are characterized by numerous circular voids distributed throughout their graphite structure. These voids represent edge sites introduced into the graphite. The figure highlights the various benefits of this structure, including reduced expansion and improved lithium-ion mass transfer. The introduced edge sites form spaces within the graphite structure that can accommodate volume changes during lithium insertion and extraction, thereby reducing expansion stress. Additionally, these edge sites improve lithium-ion mass transfer within the graphite, potentially enhancing the electrode's performance in terms of charge and discharge capabilities.
[0019] Figure 3 This is a graph comparing the performance of pure graphite electrodes and silver-added graphite electrodes. The graph plots the specific capacity (mAh / g) and coulombic efficiency (%) for both electrode types. For each electrode material, the graph shows three metrics: charge capacity (Chg), discharge capacity (DChg), and coulombic efficiency (CE). The pure graphite electrode exhibits a charge capacity of 310.18 mAh / g and a discharge capacity of 298.88 mAh / g, with a coulombic efficiency of 96.36%. In contrast, the silver-added graphite electrode demonstrates improved performance with a charge capacity of 319.20 mAh / g and a discharge capacity of 308.24 mAh / g, along with a higher coulombic efficiency of 96.57%.
[0020] Adding silver to the graphite electrode resulted in a significant increase in both charge and discharge capacity. The charge capacity improved by approximately 9 mAh / g, while the discharge capacity increased by approximately 9.4 mAh / g. This indicates that the silver additive enhances the electrode's ability to store and release charge. Coulombic efficiency, a measure of electrode charging efficiency, also showed a slight improvement of 0.21% with the addition of silver. This indicates that the graphite electrode with added silver has slightly better charge-discharge cycle efficiency compared to pure graphite.
[0021] The performance enhancement observed in silver-added graphite electrodes can be attributed to several factors. The presence of silver may potentially increase the overall conductivity of the electrode, thereby facilitating easier electron transfer during charge and discharge processes. Additionally, silver may generate more active sites for charge storage or improve the structural stability of graphite during cycling. Higher coulombic efficiency suggests that silver additives may also help reduce irreversible capacity loss during charge-discharge cycling. Figure 3 As shown in the graph, compared with pure graphite, the graphite electrode with added silver exhibits superior performance in terms of capacity and efficiency.
[0022] Figure 4This is a schematic diagram of electroreplacement in the battery electrode structure. The pre-electroreplaced electrode 10 has a positive electrode assembly 12 and a negative electrode assembly 16 separated by a separator 14. Within the negative electrode assembly 16, voids 18 and nickel nanoparticles 20 are visible. These voids 18 and nickel nanoparticles 20 are part of the initial structure of the graphite-based active material layer of the negative electrode assembly 16. A microscopic image above the pre-electroreplaced electrode 10 shows the porous nature of the negative electrode assembly 16, with the nickel nanoparticles 20 distributed throughout the negative electrode assembly. The electroreplaced electrode 22 is shown after the electroreplacement process. The overall structure of the electroreplaced electrode 22 remains unchanged, but changes occur within the negative electrode assembly 16. The nickel nanoparticles 20 have been replaced by silver nanoparticles 24 within the voids 18. A microscopic image corresponding to the electroreplaced electrode 22 shows the presence of the silver nanoparticles 24. The silver nanoparticles 24 are distributed throughout the negative electrode assembly 16.
[0023] Figure 5 This is a schematic diagram of an electrolytic cell setup 26 for electrodisplacement of a graphite electrode with silver nanoparticles. A power source 28 provides the electrical energy required to drive the electrodisplacement process. A graphite electrode 30, serving as the working electrode, is connected via a circuit 32 that facilitates the flow of electrons 34. Electrons 34 flow from the graphite electrode 30 to the counter electrode 36. A potential difference is established between the negative terminal 38 and the positive terminal 40 of the power source 28 to drive the electrochemical reaction. In the electrolytic cell setup 26, silver ions from a silver nitrate solution in the electrolyte are reduced at the surface of the graphite electrode 30, forming silver nanoparticles, while simultaneously oxidizing and displacing previously deposited nickel nanoparticles. This electrodisplacement process results in the formation of silver nanoparticles on the surface of the graphite electrode 30 and within the pores of the graphite electrode.
[0024] Figure 6 This is a flowchart of the process for forming electrode 42. The first step 44 involves loading nickel nanoparticles into a graphite active material to form a nickel-loaded graphite active material. This initial step prepares a graphite substrate with nickel nanoparticles, which will serve as a precursor for subsequent modification. The second step 46 involves hydrogenating the nickel-loaded graphite active material to form a porous graphite active material. This hydrogenation process may involve exposing the nickel-loaded graphite to hydrogen gas under specific conditions, thereby creating a porous structure within the graphite. This increases the surface area and creates additional sites for the final modification. The third step 48 includes electrodisplacement of the porous graphite active material with a silver salt solution to replace the nickel nanoparticles with silver nanoparticles, thereby forming the electrode. This electrodisplacement process replaces the nickel nanoparticles with silver nanoparticles.
[0025] While specific embodiments of the electrode structures, methods of forming such structures, and the resulting battery systems have been described in detail, these embodiments do not exhaustively cover all potential configurations. The language used in this specification is intended for descriptive purposes and not as a limitation on the scope of the invention. Modifications and changes may be made without departing from the core inventive concepts described herein. Furthermore, features and elements of the various disclosed embodiments can be combined in novel ways to form additional embodiments within the scope of the claimed subject matter, even if such combinations are not explicitly detailed in this specification.
[0026] According to the present invention, a battery is provided having: a positive electrode assembly; and a negative electrode assembly having a porous matrix of graphite-based active material, wherein lithium-philic nanoparticles occupy pores defined by the porous matrix.
[0027] According to the embodiments, the lithium-loving nanoparticles are silver nanoparticles.
[0028] According to an embodiment, the lithium-loving nanoparticles are configured to form a solid solution with lithium in the negative electrode assembly.
[0029] According to an embodiment, compared with non-porous graphite-based active materials, the porous matrix of graphite-based active materials has an increased edge surface area.
[0030] According to the embodiments, the lithium-loving nanoparticles are in the range of 0.1% to 10% by weight of the negative electrode assembly.
[0031] According to an embodiment, the porous matrix has a porosity of 10% to 50%.
[0032] According to the embodiments, the lithium-loving nanoparticles have an average diameter between 5 nanometers and 100 nanometers.
[0033] According to the present invention, an electrode assembly is provided, the electrode assembly having: a current collector; and a graphite-based active material layer deposited on the current collector, wherein electrocatalytic nanoparticles are dispersed between the particles of the graphite-based active material layer.
[0034] According to an embodiment, the graphite-based active material layer has a porous structure.
[0035] According to the embodiments, the electrocatalytic nanoparticles are silver nanoparticles.
[0036] According to an embodiment, the electrocatalytic nanoparticles are present on the surface of the graphite-based active material layer and within the pores of the graphite-based active material layer.
[0037] According to an embodiment, the graphite-based active material layer has a thickness of 50 micrometers to 200 micrometers.
[0038] According to an embodiment, the electrode assembly is a negative electrode assembly.
[0039] According to an embodiment, the current collector is copper foil.
[0040] According to the present invention, a method for forming an electrode includes: loading nickel nanoparticles into a graphite active material to form a nickel-loaded graphite active material; hydrogenating the nickel-loaded graphite active material to form a porous graphite active material; and electrodisplacing the porous graphite active material with a silver salt solution to replace the nickel nanoparticles with silver nanoparticles to form an electrode.
[0041] In one aspect of the invention, hydrogenation is performed in a temperature range of 600 degrees Celsius to 900 degrees Celsius.
[0042] In one aspect of the invention, electrodisplacement is performed at room temperature.
[0043] In one aspect of the invention, the method includes controlling the radius of silver nanoparticles by adjusting the amount of silver salt.
[0044] In one aspect of the invention, the method includes depositing the formed electrode onto a current collector.
[0045] In one aspect of the invention, porous graphite active materials can have an increased surface area compared to nickel-loaded graphite active materials.
Claims
1. A battery comprising: Positive electrode assembly; as well as A negative electrode assembly having a porous matrix of graphite-based active material and lithium-loving nanoparticles occupying pores defined by the porous matrix.
2. The battery of claim 1, wherein the lithium-loving nanoparticles are silver nanoparticles.
3. The battery of claim 1, wherein the lithium-loving nanoparticles are configured to form a solid solution with lithium in the negative electrode assembly.
4. The battery of claim 1, wherein the porous matrix of the graphite-based active material has an increased edge surface area compared to the non-porous graphite-based active material.
5. The battery of claim 1, wherein the lithium-loving nanoparticles are in the range of 0.1% to 10% by weight of the negative electrode assembly.
6. The battery of claim 1, wherein the porous matrix has a porosity of 10% to 50%.
7. The battery of claim 1, wherein the lithium-loving nanoparticles have an average diameter between 5 nanometers and 100 nanometers.
8. An electrode assembly comprising: Current collector; as well as A graphite-based active material layer is deposited on the current collector, wherein electrocatalytic nanoparticles are dispersed between the particles of the graphite-based active material layer.
9. The electrode assembly of claim 8, wherein the graphite-based active material layer has a porous structure.
10. The electrode assembly of claim 8, wherein the electrocatalytic nanoparticles are silver nanoparticles.
11. The electrode assembly of claim 8, wherein the electrocatalytic nanoparticles are present on the surface of the graphite-based active material and within the pores of the graphite-based active material layer.
12. The electrode assembly of claim 8, wherein the graphite-based active material layer has a thickness of 50 micrometers to 200 micrometers.
13. The electrode assembly of claim 8, wherein the electrode assembly is a negative electrode assembly.
14. The electrode assembly of claim 8, wherein the current collector is copper foil.
15. A method of forming an electrode, the method comprising: Nickel nanoparticles are loaded into graphite active materials to form nickel-loaded graphite active materials; The nickel-loaded graphitic active material is hydrogenated to form a porous graphitic active material. as well as The porous graphite active material is electrodisplaced with a silver salt solution to replace nickel nanoparticles with silver nanoparticles to form the electrode.