Positive Electrode Material Coating for High-Nickel Thermal Stability
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Solution Overview
Problem
Lithium nickel composite metal oxides used in lithium secondary batteries face limitations in high-temperature life characteristics, resistance, and gas generation due to poor thermal stability and surface defects caused by washing processes, which affect battery performance and safety.
Innovation Solution
A method involving primary and secondary sintering steps with specific temperature and composition control, followed by a boron-containing coating layer formation, to enhance the doping degree of aluminum on the surface of the positive electrode active material, improving thermal stability and gas generation characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the amount of nickel is increased to achieve high capacity, then capacity characteristics are improved, but thermal stability deteriorates and surface defects occur due to washing process
Solution Approach 1:
The patent applies local quality by creating a dual-layer coating structure where the inner layer (Al-containing) provides thermal stability at the core surface, while the outer layer (B-containing) provides additional protection and surface passivation. This localized functional differentiation resolves the contradiction by protecting the high-nickel core material from thermal degradation without reducing capacity.
Solution Approach 2:
The patent uses composite materials by combining aluminum-containing compounds and boron-containing compounds to form a multi-component coating layer on the positive electrode active material surface. This composite coating provides both thermal stability (from Al) and surface protection (from B), resolving the contradiction between high nickel content for capacity and thermal stability requirements.
2Manufacturing precision
If washing process is performed to remove unreacted lithium, then purity is improved, but surface defects occur and life characteristics are degraded
Solution Approach 1:
The patent applies preliminary action by forming the Al-containing coating layer on the surface before the washing process. This pre-formed protective layer prevents surface defect generation during washing while still allowing effective removal of unreacted lithium, thus maintaining both purity and life characteristics.
Solution Approach 2:
The patent uses beforehand cushioning by introducing the Al-containing coating layer as a protective buffer before the harsh washing process. This coating cushions the surface against mechanical and chemical damage during washing, preventing surface defect formation while enabling effective lithium removal.
3Ease of manufacture
If conventional low-temperature coating is applied after washing, then surface treatment is achieved, but high-temperature life characteristics and resistance characteristics are not sufficiently improved
Solution Approach 1:
The patent applies parameter changes by conducting the coating formation process at high temperature (secondary sintering temperature range) rather than low temperature. This high-temperature processing enables proper crystallization and bonding of the coating layer, significantly improving high-temperature life characteristics and resistance properties while maintaining manufacturing feasibility.
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 significantly enhances high-temperature life characteristics, resistance, and gas generation performance of lithium secondary batteries by controlling the aluminum doping degree and forming a stable coating layer, leading to improved capacity retention and reduced resistance increase rates.
Implementation Method 1
preparing a pre-sintered product by performing primary sintering on a mixture in which a positive electrode active material precursor and a lithium-containing raw material are mixed
Implementation Method 2
preparing a lithium transition metal oxide by mixing the pre-sintered product and an aluminum-containing raw material, performing secondary sintering
Implementation Method 3
dry mixing the lithium transition metal oxide and a boron-containing raw material and performing a heat treatment to form a coating layer
Data Source
AI summary
A method of preparing a positive electrode active material, a positive electrode and a lithium battery including a positive electrode active material prepared by the same are disclosed herein. In some embodiments a method includes (A) sintering on a mixture of a positive electrode active material precursor and a lithium-containing raw material to prepare a pre-sintered product, (B) sintering a mixture of the pre-sintered product and an aluminum-containing raw material to prepare a lithium transition metal oxide, and (C) heating treating a dry mixture of the lithium transition metal oxide and a boron-containing raw material to form a coating layer.