Positive Electrode Porosity Tuning for Low-SOC Battery Power
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Solution Overview
Problem
Secondary batteries face challenges in enhancing cycle performance, capacity performance, and power capability, particularly at low state of charge (SOC).
Innovation Solution
A battery design that includes a positive electrode plate with a specific porosity, electrolyte density, and active material composition, along with a lithium supplement agent, to improve wettability and ion transport, thereby enhancing power capability and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the porosity of the positive electrode plate is increased to improve electrolyte wettability and ion transport, then the power capability is enhanced, but the density and energy density of the battery deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the porosity of the positive electrode plate within the range of 20-40%, and controlling the electrolyte density and positive electrode plate compaction density within specific ranges. These parameter optimizations balance the competing requirements of improving power capability through enhanced electrolyte wettability and ion transport, while maintaining sufficient energy density by preventing excessive void space in the electrode structure.
2Quantity of substance
If the thickness of the cell is increased to increase capacity, then the capacity performance is improved, but the power capability deteriorates due to longer ion transport paths
Solution Approach 1:
The patent applies local quality by creating a non-uniform porosity distribution within the positive electrode plate structure. The electrode plate has higher porosity regions (20-40%) strategically positioned to enhance electrolyte penetration and ion transport efficiency in critical areas, while maintaining lower porosity in other regions to preserve density. This localized optimization allows the cell to achieve high capacity through increased thickness without proportionally increasing ion transport distances, as the enhanced porosity compensates for the longer paths.
3Quantity of substance
If the compaction density of the positive electrode plate is increased to improve energy density, then the capacity is enhanced, but the electrolyte wettability and ion conductivity deteriorate
Solution Approach 1:
The patent resolves this contradiction through precise parameter changes by establishing an optimal compaction density range for the positive electrode plate of 1.8-2.2 g/cm³. This parameter optimization ensures that the electrode maintains sufficient structural density for high energy density while preserving adequate porosity (20-40%) and electrolyte saturation to ensure good wettability and ion conductivity. The balanced parameter selection prevents the electrode from being either too loose (poor density) or too compact (poor ion transport).
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 design improves the wettability of the electrolytic solution, shortens the transport path of active ions, and enhances the conductivity at the positive electrode interface, resulting in improved overall power capability and cycle performance.
Implementation Method 1
the wettability of the electrolytic solution against the positive electrode plate is improved
Implementation Method 2
the conductivity of active ions at the interface of the positive electrode plate is enhanced
Data Source
AI summary
The present application provides a battery and an electric apparatus. The battery comprises a cell, a cell shell wrapping the cell and an electrolyte. The cell comprises a cathode piece, the cathode piece comprises a cathode current collector and a cathode film layer arranged on at least one surface of the cathode current collector, and the cathode film layer comprises a cathode active material. The battery satisfies the following:α×ρEL/(PD×Ccathode)+V×h/Ccell≤mEL.