Dual-Layer Positive Electrode Structure for Bondability and Capacity
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving high energy density and capacity while maintaining effective bondability between the current collector and the positive electrode active material, leading to issues in electrode plate preparation and battery performance.
Innovation Solution
A positive electrode structure comprising a current collector with a first active material layer containing olivine structured compounds and a second active material layer with layered compounds, along with specific conductive materials and binders, enhances bondability and improves capacity and lifetime characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layer positive electrode structure is used, then the manufacturing process is simple, but the bondability between current collector and active material is insufficient
Solution Approach 1:
The positive electrode is divided into two distinct layers: a first positive electrode layer containing olivine structured compound particles and a second positive electrode layer containing layered compound particles. This segmentation allows each layer to be optimized for different functions - the first layer provides strong bondability with the current collector, while the second layer contributes to capacity, thereby resolving the contradiction between manufacturing simplicity and bondability.
2Quantity of substance
If high energy density and capacity are pursued, then battery performance improves, but bondability between current collector and active material deteriorates
Solution Approach 1:
Different regions of the positive electrode are assigned different qualities: the first positive electrode layer near the current collector is designed with olivine structured compounds that provide excellent bondability, while the second layer is designed with layered compounds that provide high capacity. This local differentiation allows the electrode to simultaneously achieve both strong adhesion and high energy density without compromise.
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 proposed electrode structure facilitates easier electrode plate preparation, enhances bondability, and improves the capacity and lifetime of rechargeable lithium batteries.
Implementation Method 1
a positive electrode and a negative electrode, each including an active material that allows intercalation and deintercalation of lithium ions
Implementation Method 2
The batteries produce electrical energy from redox reactions that take place as lithium ions are intercalated into or deintercalated from the positive electrode and the negative electrode
Implementation Method 3
the first active material layer includes first particles that are olivine structured compounds represented by Formula 1 below, second particles that are layered compounds represented by Formula 2 below, a first conductive material, and a first binder
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A positive electrode for a rechargeable lithium battery includes a current collector, a first active material layer on the current collector, and a second active material layer on the first active material layer. The first active material layer includes a first particles that are olivine structured compounds, second particles that are a layered compound, a first conductive material, and a first binder. The second active material layer includes third particles that are olivine structured compounds, a second conductive material, and a second binder. The first particles are in the form of secondary particles in which a plurality of first primary particles are agglomerated, the first particles have an average diameter (D50) of about 3 µm to about 7 µm, and the second particles have an average diameter (D50) of about 3 µm to about 14 µm.