Semi-solid Electrodes with Porous Current Collectors
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Solution Overview
Problem
Conventional rechargeable batteries face challenges with high internal resistance and delamination issues due to low electronic conductivity and volume changes during charging and discharging, which affect their performance and lifespan.
Innovation Solution
The use of semi-solid electrodes with a porous current collector, where a first and second porous substrate are stacked to form a current collector, embedding a semi-solid electrode material comprising a suspension of active and conductive materials in a non-aqueous liquid electrolyte, reduces internal resistance and enhances electrical conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a thick layer of particulate paste is used as active material to achieve high capacity, then the capacity increases, but the electronic conductivity decreases
Solution Approach 1:
The patent employs a porous current collector with interconnected pores that allows the semi-solid electrode material to penetrate and form a three-dimensional conductive network. This porous structure maintains electronic conductivity pathways throughout the thick electrode while accommodating high amounts of active material, thus resolving the contradiction between capacity and conductivity.
Solution Approach 2:
The invention creates a composite structure combining a porous current collector substrate with semi-solid electrode material containing active particles, conductive additives, and electrolyte. This composite formulation ensures continuous electronic conductivity throughout the thick electrode layer while maximizing the quantity of active material for high capacity.
2Reliability
If a conventional current collector is used to provide conducting path, then the resistance reduces, but delamination occurs during charging and discharging
Solution Approach 1:
The porous current collector allows the semi-solid electrode material to deeply penetrate into its structure, creating extensive interfacial contact and mechanical interlocking. This prevents delamination during volume changes associated with charging and discharging while maintaining low resistance through the conductive porous network.
Solution Approach 2:
The semi-solid electrode material penetrates and nests within the porous structure of the current collector, creating a hierarchical integrated structure. This nesting ensures strong mechanical bonding that prevents delamination while the conductive porous framework maintains low electrical resistance.
3Quantity of substance
If active materials are made as a thick layer to increase capacity, then the capacity increases, but the structure becomes brittle
Solution Approach 1:
The porous current collector provides a flexible three-dimensional scaffold that supports the thick layer of active material. The porous structure accommodates volume changes and prevents brittleness by allowing the electrode material to integrate throughout the flexible substrate, maintaining structural integrity while enabling high capacity.
Solution Approach 2:
The composite of semi-solid electrode material and porous current collector creates a mechanically robust structure. The conductive additives and electrolyte within the semi-solid matrix provide flexibility and stress distribution, preventing brittleness even in thick high-capacity electrodes.
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
This configuration simplifies manufacturing, reduces costs, increases areal charge capacity, and improves battery performance by minimizing delamination and internal resistance, leading to enhanced energy density and extended cycle life.
Implementation Method 1
The porous current collector provides a three-dimensional conductive network throughout the electrode, reducing internal resistance
Implementation Method 2
The semi-solid electrode material includes a suspension of an active material and optionally a conductive material in a non-aqueous liquid electrolyte
Data Source
AI summary
A semi-solid electrode includes a first porous substrate and a second porous substrate stacked together to form a current collector, and a semi-solid electrode material embedded in the current collector. The semi-solid electrode material includes a suspension of an active material and a conductive material disposed in a non-aqueous liquid electrolyte. The porous substrates are at least partially disposed within the suspension such that the suspension substantially encapsulates the porous substrates. Each porous substrate in the current collector defines a pitch, and the two pitches of the two porous substrates in the current collector can be shifted with respect to each other by 30% to 70% of the pitch so as to reduce polarization effect.