Positive Electrode Precursor Orientation Control for (001) Plane Suppression
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Solution Overview
Problem
Lithium secondary batteries face limitations due to poor thermal stability and high cost of LiCoO2, and LiNiO2 has poorer thermal stability and is prone to decomposition and ignition upon internal short circuits, necessitating a method to control crystallographic characteristics of positive electrode active material precursors.
Innovation Solution
A method is developed to prepare a positive electrode active material precursor by controlling crystal orientation through a stabilization step, minimizing the growth of specific crystal planes, specifically the (001) plane, using a transition metal aqueous solution with nickel, cobalt, and manganese, and adjusting pH and ammonium cationic complexing agent concentrations to improve electrochemical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If LiCoO2 is used as positive electrode active material, then high operating voltage and excellent capacity characteristics are achieved, but poor thermal properties occur due to unstable crystal structure caused by delithiation
Solution Approach 1:
The patent applies local quality by substituting nickel at specific positions in the LiNiO2 crystal structure with cobalt and manganese elements. This creates local regions with different properties: nickel provides high capacity, while cobalt and manganese provide thermal stability. The substitution is not uniform but targeted at specific crystallographic sites to optimize both performance and stability locally.
Solution Approach 2:
The patent creates a composite material system by combining multiple transition metal elements (Li, Ni, Co, Mn) in a single oxide structure. The multi-element composition LiNi0.8Co0.05Mn0.15O2 integrates the advantages of each element: lithium for ion transport, nickel for capacity, cobalt for voltage stability, and manganese for thermal stability, achieving a synergistic effect that resolves the contradiction between power and stability.
2Quantity of substance
If LiNiO2 is used to achieve large capacity battery, then high reversible capacity of about 200 mAh/g is obtained, but poorer thermal stability occurs and decomposition causes rupture and ignition upon internal short circuit
Solution Approach 1:
The patent applies preliminary anti-action by pre-substituting nickel with cobalt and manganese during the synthesis process to prevent thermal decomposition before it can occur. The cobalt and manganese elements are incorporated into the crystal structure in advance to stabilize it, preventing the harmful decomposition reaction that would otherwise occur during charging or upon internal short circuit.
Solution Approach 2:
The patent changes the compositional parameters of the positive electrode material by adjusting the ratios of transition metal elements. Specifically, it uses LiNi0.8Co0.05Mn0.15O2 where the nickel content is reduced from pure LiNiO2 and replaced with cobalt and manganese. This parameter change maintains high capacity while fundamentally altering the thermal stability characteristics to prevent decomposition.
3Productivity
If conventional preparation methods are used for positive electrode active material precursor, then production is achieved, but uncontrolled crystal orientation leads to growth of (001) plane which affects electrochemical properties
Solution Approach 1:
The patent changes the chemical parameters of the precipitation process by controlling pH and ammonium cationic complexing agent concentration. These parameter changes create specific chemical conditions that influence crystal growth kinetics, suppressing the growth of the (001) plane and promoting desired crystal orientations. This allows conventional production methods to maintain productivity while achieving precise control over crystallographic characteristics.
Solution Approach 2:
The patent introduces ammonium cationic complexing agents as intermediaries in the precipitation process. These agents mediate the interaction between metal ions and precipitating agents, controlling the nucleation and growth of precursor particles. The complexing agents temporarily bind metal ions, regulating their availability for crystal growth and thereby controlling the crystal orientation and morphology of the precursor, which subsequently affects the electrochemical properties of the final product.
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 effectively suppresses the growth of the (001) plane, enhancing electrochemical properties and thermal stability of the positive electrode active material, leading to improved lithium ion mobility and capacity characteristics in lithium secondary batteries.
Implementation Method 1
adjusting pH and ammonium cationic complexing agent concentrations to improve electrochemical properties
Implementation Method 2
a stabilization step is included during preparation of a positive electrode active material precursor, a crystal orientation of the positive electrode active material precursor is controlled to minimize growth of a specific crystal plane
Data Source
Figure 1A~2
AI summary
The present invention relates to a method of preparing a positive electrode active material precursorin which particle growth of a (001) plane is suppressed, a positive electrode active material precursor prepared by the above method, a positive electrode active material prepared by using the positive electrode active material precursor, and a positive electrode and a lithium secondary battery which include the positive electrode active material.