Composite Positive Electrode Material for Accurate Self-Discharge Screening
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Solution Overview
Problem
The self-discharge performance of secondary batteries is difficult to screen accurately due to the flat charge/discharge plateau of positive electrode active materials, leading to challenges in screening accuracy and potential false rejections or acceptances.
Innovation Solution
A positive electrode active material comprising a first and second active material with specific dV/dSOC and ΔSOC ranges, enhancing the charge/discharge curve slope to facilitate accurate self-discharge screening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a positive electrode active material with a flat charge/discharge plateau is used, then the battery capacity is improved, but the self-discharge screening accuracy deteriorates
Solution Approach 1:
The patent changes the voltage-SOC relationship parameter by constructing a composite positive electrode active material with specific dV/dSOC and ΔSOC characteristics. The material is designed to have dV/dSOC between 0.5-2.0 mV/% and ΔSOC between 0.3-0.9 when dV/dSOC is between 0.5-2.0 mV/%, creating a steeper charge/discharge curve slope that enables accurate self-discharge screening while maintaining battery capacity
Solution Approach 2:
The patent uses a composite positive electrode active material composed of multiple components including phosphate-based materials (such as LiFePO4), silicate-based materials (such as Li2FeSiO4), and borate-based materials (such as LiFeBO3). This composite structure combines the high capacity advantages of flat plateau materials with the screening accuracy advantages of materials having steeper voltage curves
2Device complexity
If conventional positive electrode active materials are used, then the material composition is simple, but the charge/discharge curve slope is insufficient for accurate screening
Solution Approach 1:
The patent employs composite positive electrode active materials containing phosphate-based, silicate-based, and borate-based materials in specific proportions. This composite approach creates a charge/discharge curve with sufficient slope (dV/dSOC between 0.5-2.0 mV/%) while maintaining reasonable material composition complexity that is feasible for industrial production
Data Source
AI summary
Provided are a positive electrode active material, a positive electrode sheet, a secondary battery, and an electric device. The positive electrode active material includes a first active material and a second active material. The first active material and the second active material have different material compositions. In a test curve of the positive electrode active material using a state of charge SOC as an abscissa and dV/dSOC as an ordinate, 0.5≤dV/dSOC≤2.0, and 0.3≤ΔSOC<1.0, where V represents a voltage value, and ΔSOC represents a difference value of an SOC value range corresponding to the dV/dSOC value range. For self-discharge using the positive electrode active material, self-discharge screening accuracy can be improved.