Electrode Composite with Insulating Layer for Battery Safety
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Solution Overview
Problem
Secondary batteries using titanium-containing oxides as negative electrode active materials face challenges with low energy density and high operating potential, leading to reduced capacity and efficiency in rapid charge and discharge applications, particularly in vehicles where internal short circuits and heat generation are concerns.
Innovation Solution
An electrode composite is developed with a negative electrode active material-containing layer of titanium-containing oxide particles and an insulating particle layer with a surface roughness of 0.1 µm or less, which suppresses electrical short circuits and side reactions, enhancing the battery's output performance by ensuring uniform thickness and preventing physical contact between electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If titanium-containing oxides are used as negative electrode active materials, then rapid charge and discharge performance is improved, but energy density decreases
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the surface of titanium-containing oxide particles is coated with carbonaceous material. This localized modification allows the interior to maintain the rapid charge-discharge characteristics of titanium-containing oxides while the carbonaceous coating on the surface provides higher capacity, thereby resolving the contradiction between rapid performance and energy density.
Solution Approach 2:
The patent uses composite materials by combining titanium-containing oxides with carbonaceous materials in a core-shell configuration. The composite structure integrates the advantages of both materials: titanium-containing oxides provide rapid lithium ion insertion/extraction kinetics while carbonaceous materials contribute higher theoretical capacity, thus improving energy density without sacrificing rapid charge-discharge performance.
2Duration of action of stationary object
If titanium-containing oxides are used as negative electrode active materials, then cycle life is improved, but operating potential increases
Solution Approach 1:
The carbonaceous coating is applied locally on the surface of titanium-containing oxide particles, allowing the bulk material to maintain its stable crystal structure and long cycle life, while the surface coating adjusts the electrochemical properties to reduce operating potential, thus resolving the contradiction between cycle life and operating potential.
3Quantity of substance
If carbon-based negative electrodes are used, then capacity is improved, but dendrite precipitation occurs during rapid charge and discharge
Solution Approach 1:
The carbonaceous coating acts as an intermediary layer between the titanium-containing oxide core and the electrolyte. This intermediate layer provides a stable surface that facilitates uniform lithium ion deposition, preventing dendrite formation while maintaining high capacity, thus resolving the contradiction between capacity and dendrite resistance.
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 electrode composite achieves improved output performance and stability in secondary batteries by preventing electrical short circuits and side reactions, thereby enhancing energy density and cycle life while maintaining rapid charge and discharge capabilities.
Implementation Method 1
an insulating particle layer which is provided on the negative electrode active material-containing layer
Implementation Method 2
The potential of the lithium titanate is derived from a redox reaction between Ti3+ and Ti4+
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
According to one approach, an electrode composite (10) is provided. The electrode composite (10) includes a negative electrode active material-containing layer (3b) and an insulating particle layer (4). The negative electrode active material-containing layer (3b) includes negative electrode active material secondary particles (3A) having an average secondary particle size of from 1 µm to 30 µm. The insulating particle layer (4) is provided on the negative electrode active material-containing layer (3b). The insulating particle layer (4) includes a first surface (4-1) and a second surface (4-2) opposed to the first surface (4-1). The first surface (4-1) is in contact with the negative electrode active material-containing layer (3b). The second surface (4-2) has a surface roughness of 0.1 µm or less.