Gradient-Porosity Ternary Cathode Precursor for Stable High-Capacity Cells
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Solution Overview
Problem
Conventional lithium-ion battery positive electrode materials have low capacity, poor cycle stability, and safety issues due to structural instability during charging and discharging, limiting their energy density and application in electric vehicles.
Innovation Solution
A ternary positive electrode material precursor with a core, intermediate, and shell layer structure, where porosity increases sequentially, is developed using a solution coprecipitation method, incorporating nickel, cobalt, manganese, and doped elements like tungsten, enhancing structural stability and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If layered ternary positive electrode materials are used to achieve higher capacity, then the capacity and cycle performance are improved, but the structure becomes unstable during charging and discharging, transforming to spinel phase and rock salt phase, resulting in excessively fast capacity attenuation
Solution Approach 1:
The positive electrode material is divided into three distinct layers: a core layer, an intermediate layer, and an outer shell layer. Each layer has different porosity characteristics, creating a gradient structure that stabilizes the material during charging and discharging while maintaining high capacity. The segmentation prevents phase transformation by distributing mechanical stress across multiple layers with varying properties.
Solution Approach 2:
Different regions of the positive electrode material are assigned different porosity values. The core layer has lower porosity (5.4%-17.1%), the intermediate layer has medium porosity (7.8%-19.2%), and the outer shell layer has higher porosity (9%-20.1%). This local quality variation optimizes both structural stability and lithium ion transport in different regions of the material.
2Quantity of substance
If layered ternary positive electrode materials are used to achieve higher capacity, then the energy density is improved, but the thermal stability and safety performance become poor
Solution Approach 1:
The material is segmented into three layers with progressively increasing porosity from core to shell. This segmentation creates a gradient structure that enhances thermal stability while maintaining high energy density. The outer shell layer with higher porosity provides thermal stability, while the inner core layer maintains capacity.
Solution Approach 2:
The positive electrode material is designed as a composite structure combining three different phases with varying porosity. This composite approach allows the material to simultaneously achieve high energy density through the nickel-rich core and improved safety through the more stable outer shell layers with higher porosity.
3Ease of manufacture
If conventional positive electrode materials are used, then the manufacturing process is simple, but the capacity is low, restraining the improvement of overall battery capacity
Solution Approach 1:
The porosity parameter is changed across different layers of the positive electrode material. By controlling the porosity gradient (core: 5.4%-17.1%, intermediate: 7.8%-19.2%, shell: 9%-20.1%), the material achieves high capacity while maintaining a manufacturable structure through solution coprecipitation method.
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 precursor material improves cycle performance, rate performance, and energy density while preventing phase transitions, leading to longer battery life and better safety performance.
Implementation Method 1
A ternary positive electrode material precursor with a core, intermediate, and shell layer structure, where porosity increases sequentially, is developed using a solution coprecipitation method
Data Source
AI summary
Provided are ternary positive electrode material precursor and preparation method thereof, positive electrode material, positive electrode slurry, lithium-ion battery, positive electrode thereof, and electrical equipment. The ternary positive electrode material precursor includes core layer, intermediate layer, and shell layer, wherein the porosities of the core layer, the intermediate layer, and the shell layer increase sequentially. The preparation method is mixing raw materials including nickel source, cobalt source, manganese source, a precipitating agent, and a complexing agent; and performing reaction of solution coprecipitation method. The positive electrode material is made of raw materials including the ternary positive electrode material precursor. The positive electrode slurry is made of raw materials including the positive electrode material. The lithium-ion battery positive electrode is made of raw materials including the positive electrode slurry. The lithium-ion battery is made of raw materials including the lithium-ion battery positive electrode. The electrical equipment includes the lithium-ion battery.