Sintered Positive Electrode Structure With Conductive Openings
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Solution Overview
Problem
Sintered electrode active material layers in lithium secondary batteries can develop cracks during charge and discharge, leading to increased resistance and decreased battery performance, such as capacity loss.
Innovation Solution
An electrode structure is developed with a sintered plate electrode active material layer on a current collector, featuring openings penetrating through the layer, and a conductive layer comprising a conductive material and a binder on the inner surface of these openings, with a content of 0.05% to 3% by weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a sintered electrode active material layer is used to achieve high energy density, then energy density is improved, but cracks develop between grains during charge and discharge leading to increased resistance and decreased battery performance
Solution Approach 1:
The patent applies local quality by introducing a conductive coating layer specifically at the grain boundaries and surface regions of the sintered electrode active material particles. This localized treatment addresses the crack formation issue at specific locations (grain interfaces) without changing the overall sintered structure that provides high energy density. The conductive coating is applied selectively to where cracks typically form, maintaining the bulk properties needed for high capacity while improving local reliability.
Solution Approach 2:
The patent creates a composite structure by combining the sintered electrode active material particles with a conductive coating layer. This composite approach allows the inner sintered core to maintain high energy density while the outer conductive coating layer prevents crack propagation and maintains electrical conductivity at grain boundaries. The combination of these two materials with different functions resolves the contradiction between energy density and reliability.
2Quantity of substance
If a sintered electrode active material layer is bonded to the current collector to achieve high energy density, then energy density is improved, but cracks are created between grains during charge and discharge resulting in resistance increase
Solution Approach 1:
The patent applies beforehand cushioning by pre-coating the sintered electrode active material particles with a conductive material before assembling the battery. This conductive coating acts as a protective layer that cushions against the mechanical stresses and volume changes occurring during charge and discharge cycles. The coating is applied in advance to prevent crack formation at grain boundaries before the harmful effects of cycling begin, thereby preventing resistance increase while maintaining high energy density.
3Quantity of substance
If electrode active material grains are densely packed to achieve high energy density, then energy density is improved, but cracks form between grains during charge and discharge leading to capacity decrease
Solution Approach 1:
The patent applies the flexible shells and thin films principle by introducing a thin conductive coating layer around the sintered electrode active material grains. This thin film acts as a flexible shell that can accommodate the volume changes and stress variations occurring during charge and discharge cycles. The coating maintains structural integrity at grain boundaries while allowing the dense packing needed for high energy density, preventing crack formation that would otherwise compromise structural strength.
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 electrode structure enhances high-rate and lifespan characteristics of electrochemical devices by reducing resistance and preventing cracks between electrode active material grains, thereby maintaining high energy density and capacity retention.
Implementation Method 1
a conductive layer comprising a conductive material and a binder on an inner surface of the opening
Implementation Method 2
a conductive layer comprising a conductive material and a binder on an inner surface of the opening
Implementation Method 3
press-bonding the electrode active material layer to the coated current collector
Implementation Method 4
annealing the press-bonded structure to prepare the electrode structure
Data Source
AI summary
An electrode structure, a positive electrode and an electrochemical device including the same, and a method of preparing the electrode structure. The electrode structure includes a current collector; and an electrode active material layer on a surface of the current collector, wherein the electrode active material layer includes an electrode active material and an opening penetrating through the electrode active material layer; and a conductive layer comprising a conductive material and a binder on an inner surface of the opening, and wherein the content of the conductive material and the binder is 0.05% to 3% by weight on the basis of the total weight of the electrode active material layer.