Lithium Cathode Material with Phosphorus Doping for Sinterability
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Solution Overview
Problem
Lithium composite oxides used in lithium secondary batteries contain high levels of impurity elements like Na and S, which affect sinterability and battery characteristics, leading to inferior performance.
Innovation Solution
Introducing chloride of metal elements like Mn, Co, and Ni into a lithium carbonate suspension, along with phosphoric acid to control impurity levels, resulting in a cathode material with improved sinterability and battery characteristics by forming Li-A-O composite oxide particles with controlled impurity content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mixing methods are used to synthesize lithium composite oxides, then the manufacturing process is simple, but the sinterability and battery characteristics deteriorate due to high impurity content
Solution Approach 1:
The patent uses water as an intermediary medium to dissolve lithium carbonate and metal chlorides, enabling precise control of composition and impurity levels. This liquid-phase intermediary allows for homogeneous mixing and controlled precipitation, improving sinterability while maintaining manufacturing feasibility through a systematic multi-step process
Solution Approach 2:
The patent performs preliminary actions by pre-dissolving lithium carbonate and metal chlorides in water, adjusting pH levels, and controlling precipitation conditions before final sintering. These preliminary chemical preparations ensure optimal composition and low impurity content, leading to superior sinterability and battery characteristics
2Reliability
If conventional heat treatment is used to synthesize lithium composite oxides, then the process is straightforward, but battery characteristics deteriorate due to high impurity levels affecting stability
Solution Approach 1:
The patent systematically changes multiple parameters including pH level (adjusted to specific ranges), temperature (controlled during drying and sintering), concentration ratios (Li to metal ratios), and drying temperature to precisely control the composition and impurity content. This parametric control achieves low impurity levels (Na and S ≤ 100 ppm) and superior battery characteristics
Solution Approach 2:
The patent incorporates feedback control by monitoring and adjusting pH levels during the mixing process, controlling drying temperatures based on material state, and optimizing sintering conditions based on composition requirements. This feedback mechanism ensures precise composition control and consistent low impurity levels
3Reliability
If metal chlorides are introduced in lithium carbonate suspension to reduce impurities, then Na and S content decreases to 100 ppm or less, but sinterability and battery characteristics still have room for improvement
Solution Approach 1:
The patent进一步优化了多个工艺参数：将pH值精确控制在特定范围内，优化干燥温度和时间，精确控制烧结温度和气氛，调整锂与金属的摩尔比。这些参数的精确控制使得杂质含量降至100 ppm以下，同时显著提升了烧结性能和电池特性
Solution Approach 2:
The patent creates a composite oxide structure with specific phase compositions by controlling the precipitation and sintering processes. The resulting material has a composite structure that combines the benefits of low impurity content with optimized crystal phase formation, achieving superior sinterability and battery performance 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
The method enhances sinterability and battery performance by maintaining low impurity levels, specifically within the range of 20 to 100 ppm of P, thereby improving cycle and I/O characteristics while preventing adverse effects on capacity and safety.
Implementation Method 1
adding a small amount of phosphoric acid so that the P content in the Li-A-O composite oxide particles will be 20 to 100 ppm (by mass)
Implementation Method 2
subjecting this to heat treatment (oxidation treatment)
Implementation Method 3
forming an aggregate of Li-A-O composite oxide particles containing 20 to 100 ppm (by mass) of P by filtering, cleansing, drying
Data Source
AI summary
Provided is a cathode material for a lithium secondary battery composed of an aggregate of Li-A-O composite oxide particles (wherein A represents one or more metal elements selected from Mn, Fe, Co and Ni), wherein the lithium composite oxide contains 20 to 100 ppm (by mass) of P, and the total content of impurity elements excluding essential components is 2000 ppm or less. Also provided is a manufacturing method of such a cathode material for a lithium secondary battery including the steps of suspending lithium carbonate in water and thereafter introducing a metallic salt solution of one or more metal elements selected from Mn, Fe, Co and Ni in the lithium carbonate suspension, adding a small amount of phosphoric acid so that the P content in the Li-A-O composite oxide particles will be 20 to 100 ppm (by mass), and forming an aggregate of Li-A-O composite oxide particles containing 20 to 100 ppm (by mass) of P by filtering, cleansing, drying and thereafter oxidizing the obtained carbonate. This cathode material for a lithium secondary battery and its manufacturing method realize improved sinterability and battery characteristics.