Dielectric-Coated Negative Electrode Plate for Stable Battery Interfaces
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Solution Overview
Problem
Existing electrochemical devices suffer from side reactions between the electrolyte and the negative electrode interface, leading to electrolyte decomposition, gas production, and rapid decay of cycle life, along with safety concerns such as short circuits due to metal dendrite formation.
Innovation Solution
A negative electrode plate is designed with a first dielectric layer on its outer surface and a second dielectric layer inside its pores, extending from the outer surface to the inner surface of the negative active material layer. The dielectric layers are optimized in thickness and extension depth to improve interface stability, reduce side reactions, and enhance ion permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no dielectric layer is disposed on the negative electrode interface, then the structure remains simple and manufacturing cost is low, but side reactions between electrolyte and negative electrode interface occur, causing electrolyte decomposition, gas production, and rapid decay of cycle life
Solution Approach 1:
A dielectric layer is disposed on the negative electrode interface before the electrochemical device is assembled and put into service. This preliminary protective action prevents side reactions between the electrolyte and the negative electrode interface from the beginning, thereby extending cycle life without requiring complex operational procedures or post-processing treatments.
Solution Approach 2:
The dielectric layer acts as an intermediary substance between the electrolyte and the negative electrode interface. It physically separates these two components, preventing direct harmful interactions while still allowing the device to function. This intermediary layer blocks electrolyte decomposition and gas production without interfering with the core electrochemical processes.
2Reliability
If a thick dielectric layer is disposed on the negative electrode interface to prevent side reactions, then interface stability improves and side reactions are reduced, but ion permeability decreases and kinetic performance deteriorates
Solution Approach 1:
The thickness of the dielectric layer is precisely controlled within a specific range (5-50 nm). By optimizing this critical parameter, the layer becomes thin enough to allow efficient ion permeability and maintain kinetic performance, while still being thick enough to provide sufficient protection against side reactions and ensure interface stability.
Solution Approach 2:
The dielectric layer is applied with non-uniform thickness distribution: it is thinner near the pore channels to maintain ion permeability and thicker in other regions to provide adequate protection. This local variation in quality allows the structure to simultaneously achieve both interface stability and fast ion transport.
3Reliability
If no protective layer is used on the negative electrode, then manufacturing process is simple, but metal dendrites form on the negative electrode interface, inducing short circuit and deteriorating safety performance
Solution Approach 1:
The dielectric layer is disposed on the negative electrode interface during the manufacturing process, before the device is assembled and put into service. This preliminary protective measure prevents metal dendrite formation from the outset, ensuring safety performance without requiring complex additional manufacturing steps or post-processing treatments.
Solution Approach 2:
The dielectric layer serves as an intermediary barrier between the electrolyte and the negative electrode interface, preventing direct contact that would lead to metal dendrite formation. This simple intermediary structure effectively blocks the harmful process while maintaining ease of manufacture.
4Reliability
If the second dielectric layer does not extend deep enough into the pores, then manufacturing is easier and material usage is reduced, but side reactions continue to occur inside the pores, causing electrolyte decomposition and gas production
Solution Approach 1:
The extension depth of the second dielectric layer into the pores is controlled to be within a specific range (20-80% of the pore depth). By optimizing this parameter, the layer becomes deep enough to effectively prevent side reactions and electrolyte decomposition inside the pores, while not being so deep as to cause excessive manufacturing complexity or material waste.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively stabilizes the negative electrode interface, reduces irreversible capacity, improves wetting and retention of electrolyte, and enhances ion permeability, leading to improved safety, cycle, and high-temperature performance of electrochemical devices.
Implementation Method 1
a dielectric layer is disposed on a surface of the negative active material layer facing away from the negative current collector; the dielectric layer comprises a first dielectric layer on an outer surface of the negative active material layer and a second dielectric layer on an inner wall of at least a portion of pores inside the negative active material layer
Implementation Method 2
the negative electrode plate provided by the application can stabilize negative electrode interface, and reduce side reactions between electrolyte and negative electrode interface, inhibit gas production
Implementation Method 3
using an extension depth H and a thickness T1 of the first dielectric layer satisfying 0.5 ≤ H/T1 ≤ 5, the negative electrode plate provided by the application can improve wetting and retention of electrolyte on the negative electrode plate and improve ion permeability of negative electrode plate
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5B
AI summary
The invention refers to negative electrode plate (10), preparation method thereof and electrochemical device. The negative electrode plate (10) comprises: a negative current collector (11), a negative active material layer (12), and an inorganic dielectric layer (13) which are provided in a stacked manner; the negative active material layer (12) comprises opposite first surface (121) and second surface (122), wherein the first surface (121) is disposed away from the negative current collector (11); the inorganic dielectric layer (13) is disposed on the first surface (121) of the negative active material layer (12). The negative electrode plate (10) provided by the application is useful in an electrochemical device, and can result in an electrochemical device having simultaneously excellent safety performance and cycle performance.