Silicon Anode Electrode Assembly NP Tuning for Capacity Retention
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Solution Overview
Problem
Existing silicon-containing lithium-ion batteries face challenges in maintaining high energy density and long service life due to the consumption of active lithium by the negative electrode SEI film, leading to capacity reduction and increased costs.
Innovation Solution
The design of an electrode assembly with a specific ratio of capacity per unit area of the negative electrode plate to the positive electrode plate (NP) is optimized based on the weight percentage of silicon-containing active material, ensuring a current capacity retention rate of not less than 99%. This is achieved by setting the NP within the range of 1.035−0.158X to 1.206−0.184X, where X is the weight percentage of silicon-containing active material, thereby reducing the total amount of negative electrode material and minimizing swelling forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the NP value is increased to compensate for active lithium consumption by SEI film, then service life is prolonged, but energy density deteriorates and cost increases
Solution Approach 1:
The patent applies parameter changes by establishing a dynamic NP value range (1.035−0.158X≤NP≤1.206−0.184X) that varies with silicon content X, rather than using a fixed NP value. This allows optimization of both service life and energy density by adjusting NP according to the specific silicon composition of the negative electrode.
2Reliability
If the NP value is increased to ensure long service life, then capacity retention is improved, but the total amount of negative electrode material increases leading to excessive swelling force
Solution Approach 1:
The patent uses parameter changes by defining NP as a function of silicon content X, creating an optimized range that balances capacity retention with swelling force control. The linear relationship with X allows precise adjustment of negative electrode material amount to prevent excessive swelling while maintaining reliability.
3Quantity of substance
If more negative electrode material is used to increase capacity, then initial capacity is improved, but space is reduced leading to lower energy density
Solution Approach 1:
The patent applies parameter changes by optimizing the NP value based on silicon content to achieve the highest possible initial capacity within the available space. The dynamic NP range ensures maximum utilization of battery volume for energy storage without unnecessary material excess.
Data Source
AI summary
This application provides an electrode assembly, a secondary battery, and an electric apparatus. Considering that a corresponding NP value of the electrode assembly varies with an increase in the number of cycles or storage days, this application considers the design of the NP value corresponding to the electrode assembly with a current capacity retention rate of not less than m. The NP can be designed to take different values for different weight percentages of the silicon-containing active material of a negative electrode plate.