Negative Electrode-Electrolyte Tuning for High-Rate Li-Ion Safety
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Solution Overview
Problem
Lithium-ion batteries face challenges in achieving both high rate performance and safety performance, as improving rate performance often degrades safety performance due to increased temperature during high-rate discharging.
Innovation Solution
The electrochemical apparatus includes a negative electrode with a specific elongation at the yield point and median particle size of the active substance, combined with an electrolyte containing a compound with a cyano group, which enhances rate performance while reducing internal resistance and improving safety through stabilized interface adhesion and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rate performance of lithium-ion batteries is improved, then the discharge speed and power output increase, but the temperature increases and safety performance degrades
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing a cyclic carboxylate component and adjusting the ratio of cyclic carbonate to chain carbonate within 5:95 to 45:55 by volume. This parameter optimization enables the electrolyte to maintain stable SEI film formation at high rates while improving heat dissipation characteristics, thus resolving the contradiction between rate performance and temperature control
Solution Approach 2:
The patent creates a composite electrolyte system combining cyclic carboxylate (new component) with cyclic carbonate and chain carbonate (existing components). This composite formulation synergistically improves both rate performance through enhanced ionic conductivity and safety performance through stabilized SEI film that prevents thermal runaway, directly addressing the temperature-safety contradiction
2Productivity
If the rate performance is improved through electrolyte optimization, then the discharge rate increases, but the internal resistance increases and safety performance decreases
Solution Approach 1:
The patent optimizes the electrolyte composition parameters, specifically setting the cyclic carbonate to chain carbonate volume ratio between 5:95 and 45:55, and adding cyclic carboxylate at 5-95 volume%. These parameter changes reduce internal resistance by improving ionic conductivity while the cyclic carboxylate forms protective SEI films that enhance safety, simultaneously improving rate performance and reliability
Solution Approach 2:
The cyclic carboxylate acts as an intermediary substance that mediates between the electrode and the main electrolyte. It forms a stable interfacial layer (SEI film) that reduces internal resistance and prevents harmful reactions, enabling both high rate performance and improved safety performance without direct conflict
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 significantly improves the rate performance of lithium-ion batteries while reducing the thickness swelling rate under thermal abuse, thereby enhancing the safety performance by stabilizing the interface and reducing heat generation.
Implementation Method 1
the electrolyte includes a compound having a cyano group... stabilized interface adhesion and conductivity
Implementation Method 2
reducing the thickness swelling rate under thermal abuse... stabilizing the interface and reducing heat generation
Data Source
AI summary
An electrochemical apparatus, including a positive electrode, a negative electrode, and an electrolyte. The negative electrode includes a negative electrode current collector and a negative electrode mixture layer formed on the negative electrode current collector, and the negative electrode mixture layer includes a negative electrode active substance. An elongation at a yield point of the negative electrode mixture layer and D50 of the negative electrode active substance satisfy a specified relationship, and the electrolyte includes a compound having a cyano group.