Porous Composite Negative Electrode for High-Rate Lithium-Ion Charging
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in maintaining sufficient lithium ion transfer and preventing lithium depletion and precipitation during high-rate charging and discharging, particularly with Si-based active materials.
Innovation Solution
A negative electrode structure is designed with agglomerated porous conductive material particles having interconnected pores, enhancing lithium ion supply and electrolyte impregnation, which includes a combination of carbon-based and Si-based active materials to improve conductivity and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Si-based active material is used to increase capacity per unit area, then the battery capacity is improved, but lithium depletion and precipitation occur during high-rate charging
Solution Approach 1:
The patent uses porous conductive material particles with interconnected pores to create a three-dimensional network structure. This porous structure increases the surface area and provides multiple pathways for lithium ion transport, preventing lithium depletion and precipitation during high-rate charging while maintaining high battery capacity.
Solution Approach 2:
The patent creates a composite structure combining Si-based active material with porous conductive material. The Si-based material provides high capacity while the porous conductive material ensures efficient lithium ion transport and prevents harmful side reactions, resolving the contradiction between capacity and reliability.
2Speed
If electrode thickness is reduced to enable high-rate charging, then charging speed is improved, but electrode capacity decreases
Solution Approach 1:
The patent transitions from a two-dimensional planar electrode structure to a three-dimensional porous network structure. This dimensional change allows the electrode to maintain thinness for fast charging while providing increased surface area and multiple ion transport pathways that compensate for the reduced thickness, thereby maintaining capacity.
Solution Approach 2:
By incorporating porous conductive material particles with interconnected pores, the electrode achieves a three-dimensional architecture that increases effective surface area and lithium ion transport capacity without increasing electrode thickness, enabling both high charging rates and high capacity.
3Reliability
If conventional conductive material is used in thin electrodes, then electrode conductivity is maintained, but lithium salt concentration becomes insufficient for high-rate reactivity
Solution Approach 1:
The porous conductive material particles create a three-dimensional network with interconnected pores that can hold and transport electrolyte containing lithium salts. This increases the effective concentration of lithium salts at the reaction sites while maintaining excellent electrical conductivity through the porous network structure.
Solution Approach 2:
The porous conductive material acts as an intermediary structure that facilitates both electron transport (maintaining conductivity) and lithium ion transport (maintaining lithium salt concentration). The interconnected pores serve as channels for electrolyte penetration, ensuring sufficient lithium salt availability for high-rate reactivity.
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 structure effectively prevents lithium depletion and precipitation, ensuring high-rate charge and discharge performance with improved capacity and efficiency, as demonstrated by the high-capacity retention and lack of lithium dendrite formation.
Implementation Method 1
an agglomerated product where at least one, e.g., two or more porous conductive material particles having pores are agglomerated; and a negative electrode active material, wherein the pores of the adjacent porous conductive material particles within the agglomerated product are interconnected with each other
Data Source
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AI summary
A negative electrode for a rechargeable lithium battery and a rechargeable lithium battery including the same are disclosed. The negative electrode for a rechargeable lithium battery includes a negative electrode active material layer including: an agglomerated product where at least one, e.g., two or more porous conductive material particle have pores are agglomerated, wherein pores of the adjacent porous conductive material particles in the agglomerated product are interconnected with each other.