Positive Electrode Composite Material for Battery Energy Density
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Solution Overview
Problem
Existing battery technologies face challenges in balancing energy density and power performance due to the interdependence of electrode compaction density and working voltage, which is exacerbated by differences in ionic conducting performance when mixing active materials with varying particle sizes.
Innovation Solution
A positive electrode composite material comprising at least two different active materials with specific relationships between particle sizes and diffusion coefficients of active ions, ensuring a controlled diffusion time range to enhance ionic conductivity and consistent charge/discharge performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the working voltage of electrode active material is increased by doping modification, then energy density is improved, but diffusion coefficient of active ions decreases and power performance deteriorates
Solution Approach 1:
The positive electrode active material is segmented into multiple particle sizes (first particle size and second particle size), where larger particles contribute to energy density while smaller particles facilitate ion diffusion and power performance. This segmentation allows simultaneous optimization of both energy density and power performance without relying solely on doping modification.
Solution Approach 2:
Different regions of the electrode utilize different particle sizes with optimized local properties. Larger particles are used where energy storage is prioritized, while smaller particles are used where rapid ion transport is needed. This local quality differentiation resolves the contradiction between energy density and power performance.
2Speed
If particle size of active material is reduced to improve power performance, then diffusion coefficient increases, but compaction density of electrode plate decreases and energy density is affected
Solution Approach 1:
The active material is divided into at least two different particle sizes. The larger particles maintain high compaction density and energy density, while the smaller particles ensure adequate diffusion coefficients for power performance. This multi-size segmentation strategy simultaneously satisfies both requirements without compromise.
Solution Approach 2:
The electrode uses a composite structure of active material particles with different size distributions. This composite approach combines the advantages of both large particles (high density) and small particles (high diffusion rate), achieving a balance between energy density and power performance that neither particle size alone could provide.
3Use of energy by moving object
If active material particles with different particle sizes are mixed to balance energy density and power performance, then both properties are partially improved, but ionic conducting performance varies significantly and overall performance is limited
Solution Approach 1:
The patent precisely controls critical parameters including the ratio of first to second particle sizes (0.1-2.0), diffusion time ratios (0.5-2.0), and particle size distributions. By optimizing these parameters, the invention achieves consistent ionic conducting performance across different particle sizes, resolving the reliability issue associated with simple mixing approaches.
Solution Approach 2:
The invention establishes feedback control mechanisms by monitoring and adjusting particle size distributions and diffusion coefficients to maintain optimal performance. The diffusion time is controlled within specific ranges (0.5-2.0 times), ensuring consistent ionic conducting performance through systematic parameter optimization rather than random mixing.
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
The composite material achieves both high energy density and good power performance by adjusting ionic conductivity and ensuring uniform diffusion times across the electrode, allowing each active material to exhibit its inherent properties effectively.
Implementation Method 1
D1 is a diffusion coefficient of active ions of the first active material, D2 is a diffusion coefficient of active ions of the second active material
Data Source
Figure 1
AI summary
Provided is an electrical device, comprising a secondary battery. The secondary battery comprises a positive electrode sheet, the positive electrode sheet comprising a positive electrode composite material. The positive electrode composite material comprises a first active material and a second active material. The first active material and the second active material satisfy [Equation 1], wherein r1 is the primary-particle average particle size of the first active material, r2 is the primary-particle average particle size of the second active material, r1 and r2 being calculated in a same unit, D1 is the active-ion diffusion coefficient of the first active material, D2 is the active-ion diffusion coefficient of the second active material, D1 and D2 being calculated in a same unit, r1 and r2 are unequal, and/or D1 and D2 are unequal.