Porous Silicon-Graphite Electrode Layer for Fast-Charging Capacity
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Solution Overview
Problem
Conventional electrochemical apparatuses using graphite materials have limited capacity and slow charge/discharge rates, which cannot meet the increasing demands for high-capacity and rapid charging/discharging.
Innovation Solution
An electrochemical apparatus with an electrode sheet featuring a current collector and an active material layer composed of a first active material (e.g., silicon) with higher gram capacity and a second active material (e.g., graphite), along with a controlled pore structure that enhances lithium ion intercalation and reduces impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon materials are used as negative electrode material, then the gram capacity is significantly increased, but the electronic/ionic conductivity decreases and charge/discharge rate becomes slower
Solution Approach 1:
The patent applies porous silicon materials with controlled pore structures (porosity of 30-70%) to create efficient ion transmission channels. The porous structure provides direct pathways for lithium ion diffusion, reducing the solid-phase diffusion limitations while maintaining high gram capacity. The pore size and distribution are optimized to balance ion transport efficiency with capacity retention.
Solution Approach 2:
The patent employs composite structures combining silicon with conductive materials (such as carbon matrices, metal nanoparticles, or conductive polymers) to enhance electronic conductivity while preserving the high capacity of silicon. The composite architecture addresses the intrinsic low conductivity of pure silicon through synergistic material combinations.
2Quantity of substance
If the active material layer is made denser to increase capacity, then the energy density improves, but the lithium ion diffusion path becomes longer and impedance increases
Solution Approach 1:
The patent introduces vertical pore channels that create three-dimensional ion transmission pathways, transforming the traditional two-dimensional surface diffusion into multi-dimensional transport. This dimensional transition allows ions to reach deeper regions of the electrode through direct vertical paths, reducing the effective diffusion distance and impedance while maintaining high material density.
Solution Approach 2:
The dense active material layer is segmented into regions separated by pore channels, creating a hierarchical structure where the material is divided into smaller functional units. This segmentation reduces the average ion diffusion path length within each segment while maintaining overall high density, effectively lowering impedance through distributed short-path transmission networks.
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 increases the capacity and improves the charge/discharge speed of the electrochemical apparatus by creating a new lithium ion transmission channel and increasing the reaction area of the solid-liquid interface, thus meeting the demands for high-capacity and rapid charging/discharging.
Implementation Method 1
The pore structure can be fully infiltrated and filled by an electrolyte, and becomes a new lithium ion liquid phase transmission channel
Implementation Method 2
Lithium ions deeply intercalate into the electrode sheet through the newly constructed pore structure, effectively increasing the reaction area of the solid-liquid interface
Implementation Method 3
The pore structure allows the lithium ions to more easily intercalate into the active material layer in the electrode sheet, reducing the difficulty of intercalation and deintercalation of the lithium ions
Data Source
AI summary
An active material layer includes a first active material and a second active material, and a gram capacity of the first active material is greater than a gram capacity of the second active material. The active material layer has a first surface facing away from the current collector, the first surface is provided with a plurality of pore structures, and a ratio of a volume of all of the plurality of pore structures to a volume of the active material layer is A, where 2%≤A≤20%. Adding the first active material with a larger gram capacity can increase the capacity of the electrochemical apparatus. The pore structure can become a new lithium ion liquid phase transmission channel, and 2%≤A≤20%.