Dual-Layer Positive Electrode Structure for Low-Resistance Li Batteries
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving high energy density, capacity, and lifetime characteristics due to insufficient binding force between the positive electrode active material and the current collector, leading to increased resistance and hindered electrode preparation.
Innovation Solution
A positive electrode design incorporating a first and second active material layer with specific olivine structured compounds and layered compounds, along with precise particle size and dopant compositions, enhances binding force and reduces resistance, facilitating improved electrode preparation and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional positive electrode active material is used, then electrode preparation is simplified, but binding force with current collector is insufficient and resistance increases
Solution Approach 1:
The patent uses composite materials by combining olivine structured compounds (Li1+a1Mn1-x1-y1-z1B1xB2y1M2z1O3) with specific dopants (B1: Al/Ti/V/Mg; B2: transition metals) to enhance binding force between the positive electrode active material and current collector. The dopants modify the surface properties and chemical composition, improving adhesion strength without complicating the electrode preparation process.
Solution Approach 2:
The patent applies parameter changes by precisely controlling the compositional parameters (a1, x1, y1, z1, b1) and dopant concentrations (xB1, y1B2) within specific ranges. These parameter optimizations enhance binding force and reduce resistance while maintaining ease of manufacture through controlled synthesis conditions.
2Quantity of substance
If high energy density is pursued, then capacity increases, but binding force decreases and resistance increases
Solution Approach 1:
The patent achieves high capacity (4.2-4.8 mAh/cm²) while maintaining strong binding force by optimizing compositional parameters within specific ranges: 0.8≤a1≤1.2, 0.4≤x1≤0.8, 0≤y1≤0.6, 0≤z1≤0.05, and controlled dopant concentrations (xB1: 0.01-0.05, y1B2: 0.01-0.05). These parameter optimizations ensure high energy density without compromising binding force.
Solution Approach 2:
The patent uses composite materials with dual dopant system (B1 from Al/Ti/V/Mg and B2 from transition metals) to achieve high capacity while maintaining binding force. The synergistic effect of different dopants enhances both capacity and adhesion properties simultaneously.
3Reliability
If cobalt content is reduced, then cost decreases and safety improves, but performance characteristics deteriorate
Solution Approach 1:
The patent achieves excellent lifetime characteristics (92-96% capacity retention after 50 cycles at 50°C) with cobalt-free composition by optimizing the olivine structure parameters and dopant concentrations. The specific compositional ranges enable high performance without cobalt, maintaining both reliability and productivity.
Solution Approach 2:
The patent replaces expensive cobalt with cheaper alternative dopants (Al, Ti, V, Mg, and other transition metals) to reduce cost while maintaining or improving performance. The cobalt-free composition achieves better lifetime characteristics at lower material cost.
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 increases binding force with the current collector, reduces electrode resistance, and results in rechargeable lithium batteries with enhanced capacity, lifetime, and high operating voltage.
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
Li1+a1Mn1-x1-y1-z1B1xB2y1M2z1O3 (where B1 includes at least one of Al, Ti, V, and Mg; and B2 includes at least one of transition metals)
Data Source
AI summary
A positive electrode for a rechargeable lithium includes a current collector. A first active material layer is provided on the current collector, and the first active material layer includes first particles, second particles, a first binder, and a first conductive material. A second active material layer is provided on the first active material layer, and the second active material layer includes third particles, a second binder, and a second conductive material. The first particles contain an olivine structured compound, the second particles contain a layered compound, the third particles contain an olivine structured compound, the first particles are single particles, and the first particles have an average diameter of about 100 nm to about 2 μm. The first active material layer and the second active material layer have a cobalt (Co) content of less than about 100 ppm. An average diameter of the second particles is greater than the average diameter of the first particles. The third particles are single particles, and the third particle have an average diameter of about 100 nm to about 2 μm.