Secondary Battery Graphite Anode Ratio for Low-Temperature Charging
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Solution Overview
Problem
Existing secondary batteries face challenges in achieving high energy density while maintaining good electrochemical performance, particularly at low temperatures and in high-temperature cycles.
Innovation Solution
The secondary battery design incorporates a positive electrode plate with lithium-containing phosphates and a negative electrode plate made of both artificial and natural graphite, with a controlled I 3R(012) /I 2H(100) peak intensity ratio within a specific range, enhancing active ion transmission and surface stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high energy density is achieved through material composition, then energy storage capacity is improved, but electrochemical performance at low temperatures deteriorates
Solution Approach 1:
The negative electrode uses a composite of artificial graphite and natural graphite in a specific weight ratio (30:70 to 70:30). This composite structure combines the high capacity of artificial graphite with the low-temperature performance of natural graphite, resolving the contradiction between energy density and low-temperature charging performance.
Solution Approach 2:
The patent controls the peak intensity ratio I3R(012)/I2H(100) within a specific range (0.05-0.25) by adjusting the graphite composition ratio. This parameter control optimizes both the crystal structure properties and electrochemical performance, achieving high energy density while maintaining good low-temperature charging performance.
2Quantity of substance
If high energy density is achieved through material composition, then energy storage capacity is improved, but high-temperature cycle life deteriorates
Solution Approach 1:
The composite of artificial graphite and natural graphite provides both high capacity and thermal stability. The natural graphite component enhances surface stability at high temperatures, while the artificial graphite maintains high capacity, thus achieving both high energy density and long high-temperature cycle life.
Solution Approach 2:
By controlling the I3R(012)/I2H(100) peak intensity ratio within the optimal range, the patent optimizes the crystal structure to balance capacity and stability. This parameter control ensures high energy density while maintaining structural integrity during high-temperature cycling.
3Productivity
If fast charging is implemented to improve charging speed, then charging time is reduced, but lithium precipitation risk increases
Solution Approach 1:
The controlled I3R(012)/I2H(100) ratio optimizes the graphite crystal structure to facilitate faster lithium ion insertion while maintaining structural stability. This prevents lithium precipitation during fast charging by ensuring uniform ion distribution and reducing local stress accumulation.
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
This configuration improves charging performance, especially at low temperatures, and extends high-temperature cycle life, while maintaining high energy density and reducing the risk of lithium precipitation during fast charging.
Implementation Method 1
the active ions transmission performance of the negative plate can be improved
Implementation Method 2
a secondary lithium-ion battery with a negative electrode active material comprising graphite, i.e., natural and artificial graphite, and a layered transition metal oxide... this invention aims at transferring the rhombohedral-crystal structure to hexagonal-crystal structure
Data Source
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AI summary
This application discloses a secondary battery (5) and an apparatus containing the secondary batteries. The secondary battery (5) includes a positive electrode plate and a negative electrode plate, the positive electrode plate comprising a positive electrode current collector and a positive electrode film disposed on at least one surface of the positive electrode current collector and comprising a positive active material; the negative electrode plate comprising a negative electrode current collector and a negative electrode film disposed on at least one surface of the negative electrode current collector and comprising a negative electrode active material, wherein the positive active material comprises one or more of lithium-containing phosphates with olivine structure and modified compounds thereof, the negative electrode active material includes artificial graphite and natural graphite, and the negative electrode plate satisfies 0.04≤I3R(012)/I2H(100)≤0.22.