Battery Anode Composition With Staged Cut-Off Voltage Control
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Solution Overview
Problem
Secondary batteries, such as lithium-ion and sodium-ion batteries, face challenges in maintaining high mass energy density and long service life due to the swelling of silicon-based negative electrode materials during cycling, which affects their performance and lifespan.
Innovation Solution
The electrochemical apparatus employs a combination of first and second active substances, where the discharge capacity per unit mass of the first active substance is smaller than that of the second, with a life cycle divided into multiple segments, allowing for gradual increase in discharge cut-off voltage to reduce the participation of the second active substance, thereby minimizing swelling and enhancing cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based negative electrode material is used to increase mass energy density, then discharge capacity per unit mass is improved, but the negative electrode material swells greatly during cycling which reduces service life
Solution Approach 1:
The patent segments the negative electrode material into two components: silicon-based material (providing high discharge capacity) and graphite material (providing structural stability). This segmentation allows the silicon component to contribute to high mass energy density while the graphite component mitigates swelling during cycling, thereby resolving the contradiction between discharge capacity and service life.
2Reliability
If the life cycle is divided into multiple cycle segments with increasing discharge cut-off voltage, then swelling of the second active substance is reduced, but the control complexity increases
Solution Approach 1:
The patent implements dynamic control by dividing the battery's life cycle into multiple cycle segments, where the discharge cut-off voltage is progressively increased across segments. This dynamic adjustment strategy allows the system to adapt to the battery's aging characteristics, reducing swelling effects at different stages of degradation while maintaining manageable control complexity through systematic voltage progression.
Data Source
AI summary
An electrochemical apparatus including a negative electrode active substance. The negative electrode active substance includes a first active substance and a second active substance, a discharge capacity per unit mass of the first active substance is smaller than that of the second active substance, and a life cycle of the electrochemical apparatus includes N cycle segments arranged sequentially, where N is a positive integer greater than or equal to 2, each cycle segment includes at least one charge-discharge cycle of the electrochemical apparatus, and the electrochemical apparatus is charged and discharged cyclically based on the ith discharge cut-off voltage in the ith cycle segment, where 1≤i≤N and the ith discharge cut-off voltage between the 1st discharge cut-off voltage and the (N−1)th discharge cut-off voltage is smaller than the (i+1)th discharge cut-off voltage.