Composite Positive Electrode Plate for Stable High-Energy Cycling
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Solution Overview
Problem
Existing secondary batteries face challenges in cycle performance, energy density, low-temperature discharge capacity retention, and high-temperature storage performance, necessitating improvements for wider applications in energy storage and mobility sectors.
Innovation Solution
A positive electrode plate comprising two active materials, LixNiyCozMkMepOrEs and LiaAbMn1-cBcP1-dRdO4-nDn, with controlled particle sizes and specific surface areas, limits thickness change during charging and discharging, enhancing electronic and ionic conductivities, and optimizing material stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single positive electrode active material is used, then the battery structure is simple, but the cycle performance and energy density are insufficient
Solution Approach 1:
The patent employs a composite positive electrode active material system comprising Li-rich layered oxide and high-voltage spinel oxide. The Li-rich layered oxide (LixNiyCozMn1-z-mO2) provides high capacity through both transition metal oxidation and lithium extraction, while the high-voltage spinel oxide (LiaAbMn1-cBcP1-dRdO4-nDn) contributes high voltage and structural stability. This composite approach synergistically improves cycle performance and energy density while managing volume expansion issues.
2Quantity of substance
If high-capacity Li-rich layered oxide is used, then energy density increases, but volume expansion during charge-discharge deteriorates cycle performance
Solution Approach 1:
The patent combines Li-rich layered oxide with high-voltage spinel oxide to create a composite positive electrode active material. The spinel component provides structural stability that compensates for the volume expansion of the Li-rich layered oxide during lithium extraction, thereby maintaining good cycle performance while achieving high gram capacity.
Solution Approach 2:
The patent optimizes the composition parameters of both Li-rich layered oxide (x, y, z, m values) and high-voltage spinel oxide (a, b, c, d, n values) to achieve the desired balance between capacity and stability. By carefully controlling these compositional parameters, the material delivers high gram capacity while maintaining structural integrity during cycling.
3Ease of operation
If particle size is reduced to improve ionic conductivity, then low-temperature discharge capacity improves, but surface area increases leading to more interfacial reactions
Solution Approach 1:
The patent optimizes particle size parameters to achieve a balance between ionic conductivity and interfacial reaction control. By controlling the particle size within specific ranges, the material achieves improved low-temperature discharge capacity through enhanced ionic conductivity while limiting the increase in surface area that would lead to excessive interfacial reactions.
4Reliability
If thickness change during charge-discharge is not controlled, then manufacturing is simpler, but battery reliability deteriorates
Solution Approach 1:
The composite structure of Li-rich layered oxide and high-voltage spinel oxide inherently provides better dimensional stability during charge-discharge cycling. The spinel component's robust framework helps constrain the overall thickness change, improving battery reliability while maintaining reasonable manufacturing tolerances.
Data Source
AI summary
A positive electrode plate, a battery, and an electrical device are provided. The positive electrode plate includes a first positive electrode active material and a second positive electrode active material, where the first positive electrode active material includes a compound LixNiyCozMkMepOrEs, and the second positive electrode active material includes a compound LiaAbMn1-cBcP1-dRdO4-nDn, where the following is satisfied: 0.90≤m/n≤1.20.