Gas phase activation in-situ covalent bonding current collector-free electrochemical electrode and preparation method thereof

Abstract

The invention discloses a gas phase activation in-situ covalent bonding current collector-free electrochemical electrode and a preparation method thereof, glass fiber or carbon fiber is used as a skeleton, gas phase precursors such as methane, butane, silane and the like are adopted, gas molecules are activated and unstable, spontaneously migrated and adsorbed on the surface of the fiber through instantaneous interface heating, and an active layer is formed through in-situ covalent bonding; the electrode is free of a current collector, a binder and a conductive agent, coating, dipping, baking, rolling, heat preservation and high-temperature sintering are avoided in the whole process, the interface bonding strength is high, the structure is stable, solid, flexible, special-shaped, power and energy storage batteries are adapted, the system is obviously different from a traditional electrode manufacturing system, and the electrode has high industrialization value and technical universality.

Description

Technical Field

[0001] This invention relates to the field of electrochemical energy storage technology, specifically to an integrated electrochemical electrode that is gas-phase activated, in-situ spontaneously covalently bonded, and free of current collectors, binders, and conductive agents, as well as its preparation method, applicable to various secondary batteries and electrochemical energy storage devices. Background Technology

[0002] Traditional electrochemical electrodes heavily rely on metal current collectors such as copper and aluminum foil, and require the addition of binders and conductive agents, involving multiple processes including coating, drying, rolling, and high-temperature sintering. These structures suffer from drawbacks such as high weight, high proportion of inactive materials, limited energy density, weak interfacial bonding, complex manufacturing processes, and high energy consumption. Particularly in solid-state batteries, poor solid-solid interface contact, susceptibility to cracking during cycling, and continuously increasing impedance have become core bottlenecks restricting the industry's development.

[0003] Existing electrode technologies are mostly solution-based, powder-mixing, or physical coating methods, which make it difficult to achieve a one-step integrated structure with direct gas-phase activation, spontaneous molecular adsorption, in-situ covalent bonding, no solvent, no powder, no three agents, and no physical coating. They cannot fundamentally solve the problems of interface stability, structural reliability, and lightweighting. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a gas-phase activated in-situ covalently bonded current collector-free electrochemical electrode and its preparation method. This invention achieves full gas-phase reaction, in-situ spontaneous bonding, a three-free structure (no current collector, no binder, no conductive agent), and simplified preparation process. It is also compatible with multiple battery systems and aims to promote the popularization of low-cost, high-performance energy storage technologies with the goal of making technology accessible to all.

[0005] The core principle of this invention is that the gaseous precursor is activated and destabilized under instantaneous interfacial heating to form highly active free radicals. The active groups spontaneously migrate to the fiber skeleton and automatically adsorb under the drive of electric field, temperature field and surface energy, and are instantaneously covalently bonded in situ at the interface, forming a continuous, high-strength and high-stability active functional layer in one step, thus constructing an integrated current collector-free electrode.

[0006] This invention establishes two differentiated technical routes: 1) Glass fiber skeleton + methane / butane hydrocarbon source → in-situ carbon covalent conductive layer; 2) Carbon fiber skeleton + silane gas source → in-situ C-Si covalent active layer.

[0007] This invention involves no liquids, no powders, no coatings, no impregnations, no baking, no rolling, no heat preservation, and no high-temperature furnace sintering. It relies entirely on the spontaneous behavior of gas phase molecules and covalent bonding at the interface to achieve electrode forming, which is fundamentally different from traditional electrode manufacturing systems. Beneficial effects

[0008] 1. Fully vapor-phase in-situ spontaneous bonding, solvent-free, powder-free, and without complex post-processing, simplifying the process, reducing energy consumption, and controlling costs. 2. No current collector, binder, or conductive agent, which helps reduce electrode weight and increase energy density. 3. In-situ covalent bonding interface with high bonding strength, resistant to detachment, pulverization, and separation, resulting in good cycle stability. 4. Can be fabricated into vertical arrays, woven meshes, and arbitrary irregular structures, adaptable to flexible, ultra-thin, curved, and solid-state batteries. 5. Compatible with lithium / sodium / potassium multi-system batteries, adaptable to liquid, semi-solid, and all-solid-state batteries, offering strong versatility. 6. Guided by technology dissemination and industrial empowerment, its simple structure facilitates large-scale production, promoting overall industry upgrading. Detailed Implementation

[0009] Example 1 (Glass fiber mesh + methane + microwave activation) Glass fiber woven mesh was selected as a three-dimensional skeleton and placed in a closed gas-phase reaction chamber. After evacuation, methane gas was introduced at a flow rate of 30–60 sccm. Microwave instantaneous interface heating was used with a power of 600–900 W, resulting in an instantaneous surface temperature of 500–650 °C for the fiber and a reaction time of 10–30 seconds. Methane molecules were activated to form carbon free radicals, which spontaneously adsorbed and covalently bonded in situ under the drive of surface energy, forming a continuous carbon conductive layer on the glass fiber surface. After natural cooling, an integrated electrode without current collectors, binders, or conductive agents was obtained, which can be directly used as the positive electrode conductive skeleton for lithium-ion and sodium-ion batteries.

[0010] Example 2 (Vertical Array Carbon Fibers + Silane + Microwave Activation) Vertically arrayed carbon fibers were selected as the skeleton, with a fiber spacing of 20–200 μm and a height of 100–2000 μm, and placed in a gas-phase reaction chamber. After evacuation, silane gas was introduced at a flow rate of 10–30 sccm. Microwave instantaneous interface heating was used with a power of 700–1200 W, an instantaneous fiber surface temperature of 600–800 ℃, and a reaction time of 5–20 seconds. The active silicon produced by silane cracking formed C-Si covalent bonds with the carbon fibers in situ, generating a silicon-based active layer. A high-capacity anode without current collectors was obtained, and the cycle stability and rate performance can be further improved by lithium, sodium, and potassium alkali metal doping.

[0011] Example 3 (Glass fiber mesh + butane + plasma activation) Glass fiber mesh was selected as a three-dimensional skeleton and placed in a closed gas-phase reaction chamber. After evacuation, butane gas was introduced at a flow rate of 20–40 sccm. Instantaneous plasma interface heating was used with a power of 500–800 W, resulting in an instantaneous surface temperature of 450–600 °C for the fiber and a reaction time of 15–40 seconds. Butane molecules were activated to form carbon free radicals, which spontaneously adsorbed and covalently bonded in situ under the drive of surface energy, forming a continuous carbon conductive layer on the glass fiber surface. After natural cooling, an integrated electrode without current collectors, binders, or conductive agents was obtained, which can be directly used as the positive electrode conductive skeleton of sodium-ion batteries.

Claims

1. A method for preparing a gas-phase activated in-situ covalently bonded current collector-free electrochemical electrode, characterized in that: Using glass fiber or carbon fiber as a three-dimensional framework, the three-dimensional framework can be at least one of a vertical array structure, a woven mesh structure, a two-dimensional mesh structure, or an arbitrary custom-designed three-dimensional irregular structure; the gaseous precursor path is selected according to the framework material. (1) At least one hydrocarbon gas, such as methane or butane, is introduced into the glass fiber skeleton and activated by instantaneous interfacial heating, forming a carbon-based conductive layer in situ through spontaneous covalent bonding on the fiber surface. (2) Silane gas is introduced into the carbon fiber skeleton and activated by instantaneous interfacial heating, forming a C-Si covalent active layer in situ on the fiber surface through spontaneous covalent bonding; and at least one alkali metal element from lithium, sodium, and potassium can be selectively introduced for doping or alloying; the resulting electrode has no current collector, no binder, and no conductive agent, and the entire preparation process is without coating, impregnation, baking, rolling, heat preservation, or high-temperature sintering, and can be directly used as the negative or positive conductive skeleton of lithium-ion batteries, sodium-ion batteries, or potassium-ion batteries.

2. The method according to claim 1, characterized in that, The instantaneous interface heating is selected from at least one of microwave, plasma, laser, induction heating, flash heating, and rapid infrared heating.

3. The method according to claim 1, characterized in that, The fiber spacing of the vertical array structure is ≥1μm, and the fiber height is ≥20μm.

4. The method according to claim 1, characterized in that, The woven mesh and two-dimensional mesh structure can be die-cut and rolled into sheet, roll, column, flexible curved surface or irregular structure.

5. The method according to claim 1, characterized in that hydrocarbon gas and silane gas can be introduced simultaneously to form a carbon-silicon covalent bond composite conductive layer in situ on the glass fiber or carbon fiber skeleton.

6. The method according to claim 1, characterized in that, The gaseous precursor, after activation, forms highly active free radicals that spontaneously migrate, automatically adsorb, and instantaneously bond in situ under the drive of electric field, temperature field, or surface energy.

7. The method according to claim 1, characterized in that, The alkali metal element is introduced by at least one of the following methods: gas phase doping, liquid phase impregnation, solid phase mixing, or in-situ alloying.

8. The method according to claim 1, characterized in that, The electrode is suitable for liquid batteries, semi-solid batteries and all-solid batteries, and can be used in power batteries, energy storage batteries, flexible batteries and irregularly shaped batteries.

9. The method according to claim 1, characterized in that, The electrode is formed in situ in one step in the gas phase, eliminating the need for liquid phase coating, powder mixing, and subsequent high-temperature sintering processes.

10. A current collector-free electrochemical electrode, characterized in that... It is prepared by the method described in any one of claims 1-9, comprising a glass fiber or carbon fiber skeleton, an in-situ covalently bonded carbon layer / silicon layer / carbon-silicon composite layer, and an optional alkali metal doped phase, forming an integrated self-supporting electrode structure.