Layered Negative Electrode Structure for Fast-Charging Silicon Batteries
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Solution Overview
Problem
Secondary batteries face a challenge in achieving both high energy density and fast charging capabilities, as increasing energy density often prolongs charging time.
Innovation Solution
The negative electrode plate is designed with distinct regions, utilizing silicon-based and carbon-based materials in specific configurations to enhance ion transport, reduce particle damage, and optimize pore structure, thereby improving both energy density and fast charge performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the energy density of the secondary battery is increased, then the charging time of the secondary battery is prolonged
Solution Approach 1:
The negative electrode film layer is divided into three distinct regions along the thickness direction: a first region (0-0.3H from second surface) containing silicon-based material for high capacity, a second region (0.3H-0.7H) with different composition for transition, and a third region (0.7H-H) for surface protection. This segmentation allows each region to perform specialized functions that collectively resolve the contradiction between energy density and charging speed.
Solution Approach 2:
Different regions of the negative electrode film layer are assigned different material compositions and structures optimized for their specific locations. The first region uses silicon-based material with high theoretical capacity for energy density, while the third region has enhanced protective characteristics for fast charging stability. This local quality differentiation enables the electrode to simultaneously achieve high energy density and fast charging performance.
2Quantity of substance
If silicon-based material is used to increase capacity, then particle structure damage occurs under rolling pressure
Solution Approach 1:
The third region of the negative electrode film layer, located at the surface portion (0.7H-H) farthest from the current collector, is designed with materials and structures that provide protective characteristics. This region acts as a cushioning layer that absorbs and distributes rolling pressure before it reaches the silicon-based material particles in the first region, thereby preventing particle structure damage while preserving the high capacity advantage of silicon.
Solution Approach 2:
The negative electrode film layer structure functions as a protective shell system, where the third region forms an outer protective layer that shields the inner silicon-based material particles from mechanical damage. This shell-like structure allows the brittle silicon particles to maintain their high capacity properties without suffering from compressive damage during battery assembly and operation.
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 solution enables secondary batteries to achieve high energy density while supporting rapid charging, with improved ion diffusion and reduced side reactions, leading to enhanced cycling performance.
Implementation Method 1
the silicon-based material being the secondary particles can provide more ion intercalation channels, which is also conducive to the rapid diffusion of ions from the surface layer of the particles to the bulk phase
Implementation Method 2
improve the pore structure of the first region of the negative electrode film layer, enhance the wettability and retention characteristics of the negative electrode film layer with respect to the electrolyte solution
Data Source
AI summary
A secondary battery and an electric apparatus are disclosed. The secondary battery includes a negative electrode plate including a negative electrode current collector and a negative electrode film layer with a thickness of H; a first surface away from the negative electrode current collector; and a second surface opposite the first surface. A first region of the negative electrode film layer includes a first active material with a thickness range from the second surface of the negative electrode film layer to 0.3H. The first active material comprises a first silicon-based material, which comprises secondary particles formed by aggregation of primary particles. A second region of the negative electrode film layer comprises a second active material with a thickness range from the first surface of the negative electrode film layer to 0.3H.