Porous Negative Electrode Plate for Low-Temperature Rate Performance
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Solution Overview
Problem
Existing secondary battery technologies face challenges in achieving high discharge rate performance at low temperatures due to reduced compacted density, capacity loss, and increased costs associated with methods like reducing active material particle size and coating modifications.
Innovation Solution
A negative electrode plate with a specific pore structure and tap density is developed, featuring negative electrode active material particles with pores that enhance lithium intercalation channels, improving kinetic performance and charge/discharge performance at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the particle size of active material is reduced to shorten lithium intercalation path, then rate performance is improved, but compacted density and gram capacity are greatly lost
Solution Approach 1:
The patent applies porous materials by constructing active material particles with controlled internal pore structures. The pores occupy 3-15% of the particle cross-sectional area and have diameters of 0.5-5 μm, creating channels that facilitate lithium ion transport without requiring particle size reduction. This maintains high compacted density while improving rate performance through the porous pathway network.
Solution Approach 2:
The patent transitions from one-dimensional surface contact to three-dimensional internal pore network for lithium ion transport. By creating pores within the particle structure rather than reducing particle size, the invention adds internal transport dimensions, allowing lithium ions to access multiple pathways simultaneously, thereby improving rate performance without sacrificing capacity.
2Speed
If coating modification is applied to improve low temperature discharge rate performance, then rate performance is improved, but costs increase
Solution Approach 1:
The patent applies parameter changes by optimizing the pore structure parameters (pore diameter 0.5-5 μm, pore area ratio 3-15%, tap density 0.8-1.4 g/cm³) of the active material particles. These parameter optimizations improve low-temperature discharge rate performance through enhanced ion transport, eliminating the need for expensive coating modifications while maintaining manufacturing simplicity.
3Productivity
If pores are added to active material particles to increase contact surface with electrolyte, then lithium intercalation channels are increased, but side reaction with electrolyte is intensified
Solution Approach 1:
The patent applies parameter changes by precisely controlling the pore diameter (0.5-5 μm) and pore area ratio (3-15%) to optimize the balance between lithium ion transport and side reaction suppression. The tap density is also controlled at 0.8-1.4 g/cm³ to ensure proper packing. These parameter optimizations create sufficient intercalation channels while limiting excessive electrolyte contact that would cause harmful side reactions.
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 optimized negative electrode plate significantly enhances the rate performance of secondary batteries at low temperatures by increasing lithium diffusion and reducing side reactions, while maintaining suitable processing performance.
Implementation Method 1
The negative electrode active material particles have pores, especially having pores inside, which can greatly enlarge a contact surface between the negative electrode plate and an electrolyte
Implementation Method 2
This obviously increases the number of lithium intercalation channels for active ions, such as lithium ions, so that the active ions are easier to diffuse
Data Source
AI summary
A negative electrode plate includes a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material. The negative electrode active material includes negative electrode active material particles, the negative electrode active material particles including a first particle having a pore. In a 200 μm×200 μm region of a cross section of the negative electrode active material layer along the thickness direction of the negative electrode active material layer, the negative electrode active material satisfies 0.10≤TD−0.05×(1/X)≤0.40, where X represents a ratio of an average cross-sectional area of the pore in the first particle to an average cross-sectional area of the first particle, and 4.0%≤X≤15%, and TD represents a value of a tap density of the negative electrode active material expressed in g/cm3.