Thick Electrodes for Electrochemical Cells Using Conductive Adhesive Layers
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Solution Overview
Problem
Conventional lithium-ion batteries face challenges in creating thick electrodes with sufficient loading capabilities due to materials like lithium manganese iron phosphate, which have large specific surface areas and low tap densities, leading to issues such as electrode cracking and limited capacity loading during the wet coating process.
Innovation Solution
The development of electrodes with lithium manganese iron phosphate (LiMnxFe1-xPO4) that include a current collector and electroactive material layers, where the electroactive material layers have thicknesses greater than 150 μm to less than 5 mm, and areal capacities greater than 4 mAh/cm2 to less than 50 mAh/cm2, along with electronically conductive adhesive layers and a meshed current collector to enhance structural integrity and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional wet coating processes are used with low-tap-density materials, then the coating process is simple and easy to manufacture, but the electrode thickness is limited and energy density is low
Solution Approach 1:
The patent changes the physical and chemical parameters of the coating process by using a slurry composition with specific viscosity modifiers, solvents, and additives that enable the formation of thick, uniform coatings without cracking. This allows the electrode thickness to be increased from conventional limits to greater than 150 μm while maintaining manufacturing feasibility through controlled parameter adjustments in the slurry formulation and drying process.
2Volume of moving object
If electrode thickness is increased to improve energy density, then capacity loading increases, but electrode cracking occurs due to low tap density materials
Solution Approach 1:
The patent creates a composite slurry material combining low-tap-density electroactive material particles with binders, conductive additives, and viscosity-modifying agents. This composite formulation maintains the high energy density benefits of low-tap-density materials while the binder and additive matrix provides structural support that prevents cracking during drying and cycling, enabling thick electrode construction with improved reliability.
Solution Approach 2:
The patent utilizes the inherent porosity of low-tap-density materials and incorporates porous structure control through the slurry formulation. The controlled porous network allows for electrolyte penetration and ion transport while the interconnected structure accommodates volume changes during cycling, preventing crack formation and maintaining structural integrity in thick electrodes.
3Use of energy by moving object
If low-tap-density materials are used to achieve high energy density, then energy density increases, but areal capacity is limited in conventional thin electrode designs
Solution Approach 1:
The patent transitions from two-dimensional thin electrode designs to three-dimensional thick electrode structures. By increasing the thickness dimension while maintaining material properties through the specialized slurry formulation, the total areal capacity increases significantly. This dimensional change allows low-tap-density materials to contribute their full energy density potential across a larger volume, achieving both high energy density and high areal capacity simultaneously.
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 approach allows for the creation of high-capacity electrodes with improved structural integrity and increased areal capacity, overcoming the limitations of low-tap-density materials and enabling thicker electrode designs while maintaining high energy density.
Implementation Method 1
lithium ions may move from the positive electrode to the negative electrode during charging of the battery, and in the opposite direction when discharging the battery
Implementation Method 2
The electrolyte is suitable for conducting lithium ions between the electrodes
Implementation Method 3
Concurrently, electrons pass through an external circuit from the negative electrode to the positive electrode
Implementation Method 4
Such lithium ions may be assimilated into the material of the positive electrode by an electrochemical reduction reaction
Implementation Method 5
the negative electrode may contain a comparatively high concentration of intercalated lithium (such as in the instance of graphite-containing anodes), which is oxidized into lithium ions and electrons
Data Source
AI summary
The present disclosure relates to high capacity (e.g., areal capacity greater than about 4 mAh/cm2 to less than or equal to about 50 mAh/cm2) electrodes for electrochemical cells. An example electrode may include a current collector (e.g., meshed current collector) and one or more electroactive material layers having thicknesses greater than about 150 μm to less than or equal to about 5 mm. The electroactive material layers may each include lithium manganese iron phosphate (LiMnxFe1-xPO4, where 0≤x≤1) (LMFP). The electrode may further include one or more electronically conductive adhesive layers disposed between the current collector and the electroactive material layers. The adhesive layers may include one or more polymer components and one or more conductive fillers. The electroactive material layers may be gradient layers, where sublayers closer to the current collector has a lower porosity than layers further from the current collector.