Negative Electrode Binder Distribution for Low-Temperature Battery Performance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium ion secondary batteries used in vehicle drive batteries face challenges in maintaining high reaction rates at low temperatures due to decreased lithium ion deintercalation and intercalation rates, which limits their performance and reliability in varying temperature environments.
Innovation Solution
Incorporating a rubber-based binder or resin with a binder function in the negative electrode active material layer, particularly in the surface vicinity, with a mass concentration ratio of 2.0≤(A/B)≤3.8, to enhance the reaction rate and maintain low resistance rise ratios during charge-discharge cycling at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional binder is used in the negative electrode active material layer, then the battery can be manufactured with standard materials, but the reaction rate decreases and resistance rises in low-temperature environments
Solution Approach 1:
The patent applies local quality by concentrating the rubber-based binder specifically in the surface vicinity of the negative electrode active material layer rather than uniformly distributing it throughout. This localized concentration creates a binder-rich surface region that facilitates lithium ion transport at low temperatures, directly addressing the technical contradiction by improving surface-level reaction kinetics without requiring uniform binder distribution throughout the entire electrode structure.
Solution Approach 2:
The patent employs parameter changes by controlling the mass concentration ratio of the rubber-based binder in the surface vicinity relative to the total binder content, specifying that this ratio should be between 2.0 and 3.8. This quantitative parameter control optimizes the binder distribution to maintain low resistance and high reaction rates in cold conditions, resolving the contradiction between reliability and productivity by tuning the binder concentration parameter.
2Power
If high-rate charging and discharging are required for vehicle drive batteries, then power output increases, but electrode debris generation and reliability issues worsen
Solution Approach 1:
The patent applies preliminary action by pre-forming a negative electrode structure with concentrated rubber-based binder in the surface region before the battery undergoes high-rate charge-discharge cycling. This pre-configured binder distribution prepares the electrode to handle high current loads by ensuring adequate lithium ion transport pathways are already in place at the surface, preventing electrode degradation and debris generation during subsequent high-power operation.
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 maintains high lithium ion reaction rates and low resistance rise ratios in low-temperature environments, ensuring improved performance and reliability for vehicle drive batteries.
Implementation Method 1
the reaction rate when deintercalating or intercalating, in the negative electrode active material layer, the chemical species that serves as the charge carrier in the secondary battery
Data Source
AI summary
A nonaqueous secondary battery 100A has a negative electrode sheet 240A in which a negative electrode active material layer 243A is held by a negative electrode current collector 241A. Contained within the negative electrode active material layer 243A is a binder 730 which includes a rubber-based binder or a resin having a binder function. The rubber-based binder or the resin having a binder function is abundantly present, within the negative electrode active material layer 243A, in a surface vicinity A1 of the negative electrode active material layer 243A.