Graphite Anode Material Tuning for High-Temperature Battery Storage
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Solution Overview
Problem
Existing graphite negative active materials in batteries face challenges in achieving a balance between structural strength, crystallite size, and graphitization degree, leading to issues with high-temperature storage performance, cycle life, and capacity recovery.
Innovation Solution
A graphite negative active material is formulated with specific ranges for crystallite sizes (La and Lc) and structural strength (S) combined with graphitization degree (G) to optimize lithium intercalation and deintercalation, enhancing capacity recovery and high-temperature storage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the crystallite size and graphitization degree of graphite negative active material are increased to improve capacity, then the structural strength decreases leading to poor high-temperature storage performance
Solution Approach 1:
The patent applies parameter changes by precisely controlling the crystallite size parameters (La and Lc) within specific ranges (La: 10-50 nm, Lc: 5-20 nm) and adjusting the degree of graphitization to balance capacity and structural strength. This quantitative parameter optimization resolves the contradiction by finding the optimal point where both capacity and structural integrity are maintained.
Solution Approach 2:
The patent creates a composite structure by controlling the crystallite morphology and combining different crystallite orientations. The specific control over La and Lc ratios produces a composite-like internal structure that simultaneously provides high capacity pathways and structural reinforcement, resolving the trade-off between capacity and strength.
2Productivity
If the crystallite size is increased to improve lithium intercalation performance, then the cycle life decreases due to structural degradation
Solution Approach 1:
The patent uses parameter changes by establishing specific ranges for crystallite size (La: 10-50 nm, Lc: 5-20 nm) that optimize lithium intercalation kinetics while preventing structural degradation. This controlled parameter adjustment ensures fast lithium insertion/extraction without compromising the structural stability needed for long cycle life.
3Reliability
If the degree of graphitization is increased to improve electrical conductivity, then the structural strength decreases leading to capacity loss at high temperature
Solution Approach 1:
The patent applies parameter changes by optimizing the degree of graphitization within specific bounds rather than maximizing it completely. This controlled graphitization level provides sufficient electrical conductivity for reliable battery operation while maintaining enough structural strength to prevent capacity loss during high-temperature storage.
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 optimized graphite negative active material achieves a high capacity recovery rate and improved high-temperature storage performance, suitable for traction batteries in electric vehicles and energy storage applications.
Implementation Method 1
optimize lithium intercalation and deintercalation, enhancing capacity recovery and high-temperature storage performance
Data Source
AI summary
Disclosed are a graphite negative active material, a negative electrode plate, a secondary battery, and a device. The graphite negative active material satisfies 215 ≤ La × S + La × G ≤ 256, wherein S is the structural strength of the graphite negative active material, wherein the structural strength is the ratio of the volume average diameter Dv50 after powder compaction under a pressure of 20 KN to the volume average diameter Dv50 before powder compaction of the graphite negative active material; La is the crystallite size of the graphite negative active material in the a-axis direction measured by XRD in units of nm; and G is the degree of graphitization of the graphite negative active material. The secondary battery of the disclosure has superior high-temperature storage performance and calendar life.