Composite Cathode Secondary Battery for Thermal Stability
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Solution Overview
Problem
Current lithium-ion batteries using ternary materials as positive electrode materials face challenges with poor high-temperature performance, cycle performance, and structural stability, leading to safety concerns.
Innovation Solution
A secondary battery design that incorporates a positive electrode material composed of a layered structure material and an olivine structure material, with a specific mass ratio, to introduce two stages of discharge voltage platforms, reducing the discharge depth of the layered structure material and enhancing thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If ternary materials are used as positive electrode materials, then high energy density and high voltage platform are achieved, but high-temperature performance and structural stability deteriorate
Solution Approach 1:
The patent applies composite materials by combining layered structure material (LiNi0.8Co0.1Mn0.1O2) and olivine structure material (LiFePO4) in a specific mass ratio range. The layered structure material provides high energy density and high voltage platform, while the olivine structure material contributes to structural stability and thermal stability. This composite positive electrode material resolves the contradiction between achieving high energy density and maintaining structural stability.
2Power
If ternary materials are used as positive electrode materials, then high voltage platform is achieved, but safety performance deteriorates
Solution Approach 1:
The composite positive electrode material combines layered structure material (providing high voltage platform) with olivine structure material (providing safety). The olivine structure material has inherent thermal stability that prevents thermal runaway, thereby improving safety performance while maintaining the high voltage platform characteristics of the layered structure material.
Solution Approach 2:
The patent optimizes the mass ratio parameters of the two materials to achieve the desired balance between voltage platform and safety performance. By adjusting the proportion of olivine structure material within the specified mass ratio range, the safety performance is enhanced while maintaining adequate voltage platform.
3Use of energy by moving object
If layered structure material is used alone, then high energy density is achieved, but thermal stability deteriorates
Solution Approach 1:
The patent combines layered structure material (high energy density) with olivine structure material (high thermal stability). The olivine structure material acts as a thermal stabilizer that prevents thermal runaway, thereby resolving the contradiction between achieving high energy density and maintaining thermal stability.
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 battery exhibits improved voltage and capacity performance while reducing the risk of thermal runaway, thereby enhancing safety performance and thermal stability.
Implementation Method 1
a positive electrode material including a first active material and a second active material... the first active material is a layered structure material... the second active material is an olivine structure material... A discharge curve of the secondary battery has a first voltage platform and a second voltage platform
Data Source
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AI summary
A secondary battery belonging to the technical field of batteries is provided. The secondary batter includes a positive electrode sheet, a separator, and a negative electrode sheet. The positive electrode sheet includes a positive electrode material including a first active material and a second active material. The first active material is a layered structure material, and the second active material is an olivine structure material. A mass ratio of the second active material to a sum of masses of the first active material and the second active material is 5 wt% to 30 wt%. A discharge curve of the secondary battery has a first voltage platform and a second voltage platform.