Positive Electrode Active Material Layer for Fast-Charging Secondary Batteries
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Solution Overview
Problem
Lithium-ion secondary batteries used in electric and hybrid vehicles face degradation issues due to temperature fluctuations, leading to reduced capacity, increased internal resistance, and accelerated degradation from fast charging, necessitating improved safety, cycle performance, and higher capacity.
Innovation Solution
A secondary battery design incorporating a positive electrode active material layer with a layered rock-salt structure and reduced graphene oxide layers, which enhances conductivity and stability, and includes a carbon-containing compound to improve charge-discharge efficiency and reduce degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional secondary batteries are used for fast charging, then charging speed is improved, but degradation is accelerated and cycle life is reduced
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core and outer shell have different compositions and functions. The core provides high capacity while the shell protects against degradation, allowing fast charging without sacrificing cycle life. This localized differentiation of material properties at different spatial positions resolves the contradiction between charging speed and reliability.
Solution Approach 2:
The patent uses composite materials by combining different electrode materials (e.g., lithium cobalt oxide core with lithium iron phosphate shell, or various NCM compositions) to create a positive electrode that exhibits both fast charging capability and long cycle life. The composite structure leverages the advantages of each material while mitigating their individual weaknesses, directly addressing the technical contradiction.
2Adaptability or versatility
If the temperature range for battery operation is expanded, then adaptability to different environments is improved, but control complexity and safety measures increase
Solution Approach 1:
The patent employs parameter changes by formulating electrode materials with specific compositional ratios and structural characteristics that inherently maintain stability across a wide temperature range from -50°C to +60°C. By adjusting material parameters (composition, crystal structure) rather than adding complex control systems, the battery achieves broad temperature adaptability without proportionally increasing device complexity.
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 provides a secondary battery with improved rate characteristics, safety, and cycle performance, enabling higher capacity and longer vehicle mileage while reducing charging time and degradation risks.
Implementation Method 1
graphene has been attracting a great deal of attention because of its excellent conductivity
Implementation Method 2
a positive electrode active material layer including a first graphene layer, a second graphene layer, and a positive electrode active material
Data Source
AI summary
A secondary battery with favorable cycle performance is provided. Alternatively, a secondary battery with higher capacity is provided. A positive electrode active material layer including a first graphene layer, a second graphene layer, and a positive electrode active material. The first graphene layer includes a first region covering the positive electrode active material. The second graphene layer includes a second region covering the positive electrode active material and a third region overlapping with the first region. The first region includes a plane positioned between the positive electrode active material and the third region and formed of arranged six-membered carbon rings. The positive electrode active material includes a fourth region with a layered rock-salt structure. A lithium layer with a layered rock-salt structure included in the fourth region is substantially perpendicular to the plane formed of six-membered carbon rings and included in the second region.