Lithium Metal Composite Oxide Powder Surface Treatment
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Solution Overview
Problem
Lithium metal composite oxides with a layered crystal structure used in lithium secondary batteries face issues with chemical reactions at high temperatures, leading to decreased capacity and charge-discharge cycle ability, and the surface treatment methods introduce impurities that reduce efficiency and low-temperature output characteristics.
Innovation Solution
A lithium metal composite oxide powder with a surface portion containing Al, Ti, or Zr, where the amount of surface LiOH and Li2CO3 is minimized, and the ratio of integral intensities of specific crystal planes is optimized to suppress electrolyte reactions and maintain low-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the particle surface of lithium metal composite oxide is coated with metal or metal oxide to suppress chemical reactions at high temperature, then the charge-discharge cycle ability is improved, but impurities remain on the particle surface reducing charge-discharge efficiency and low-temperature output characteristics
Solution Approach 1:
The patent applies parameter changes by precisely controlling the water washing conditions (temperature, time, pH) and heat treatment parameters (temperature range of 50-150°C, time range of 0.5-5 hours) to remove surface impurities while preserving the protective coating. This optimization of process parameters enables simultaneous achievement of low surface LiOH/Li2CO3 content and maintained cycle stability.
Solution Approach 2:
The patent employs composite materials by creating a surface coating composed of multiple metal oxides (Al, Ti, Zr) that work synergistically. This composite coating structure provides both protective function against high-temperature degradation and facilitates efficient ion transport, while the subsequent water washing removes harmful impurities without damaging the composite coating structure.
2Reliability
If surface treatment is applied to lithium metal composite oxide particles, then chemical reaction with electrolyte is suppressed, but low-temperature output characteristics deteriorate due to impurity formation
Solution Approach 1:
The patent optimizes process parameters by controlling water washing temperature (50-150°C) and heat treatment conditions to remove surface impurities that hinder low-temperature performance. This parameter optimization maintains the protective coating's chemical stability function while eliminating impurity-related resistance that degrades power output at low temperatures.
Solution Approach 2:
The patent applies the extraction principle by selectively removing harmful surface impurities (LiOH, Li2CO3) through controlled water washing and heat treatment processes. This extraction of detrimental substances preserves the beneficial protective coating while eliminating factors that reduce low-temperature output characteristics.
3Reliability
If aluminum is added to lithium metal composite oxide to form surface coating, then charge-discharge cycle ability improves, but rock salt layer forms on particle surface reducing performance
Solution Approach 1:
The patent controls the water washing temperature (50-150°C) and heat treatment parameters to prevent excessive formation of rock salt layer while effectively removing surface impurities. This parameter control maintains the protective coating's cycle-stability function without generating harmful rock salt phase that would degrade performance.
Solution Approach 2:
The patent applies local quality by creating a controlled surface coating with specific composition and structure that provides protection where needed while preventing unwanted phase transformation. The surface coating maintains its protective function locally without converting to harmful rock salt structure, achieving spatial differentiation of material properties.
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 solution enhances charge-discharge cycle ability and low-temperature output characteristics by reducing impurities and rock salt layer formation, improving the efficiency and performance of lithium secondary batteries, especially in vehicular applications.
Implementation Method 1
the particle surface of a lithium metal composite oxide having a layered crystal structure is coated with a metal or a metal oxide
Implementation Method 2
subjecting the dispersion to a heat treatment at 600° C.
Implementation Method 3
lithium dissolves out as ions from a positive electrode and migrates to a negative electrode and is intercalated therein
Data Source
AI summary
A positive electrode active material comprising a lithium metal composite oxide having a layered crystal structure provides a novel lithium metal composite oxide powder which can suppress the reaction with an electrolytic solution and raise the charge-discharge cycle ability of a battery, and can improve the output characteristics of a battery. A lithium metal composite oxide powder comprises a particle having a surface portion where one or a combination of two or more (“surface element A”) of the group consisting of Al, Ti and Zr is present, on the surface of a particle comprising a lithium metal composite oxide having a layered crystal structure, wherein the amount of surface LiOH is smaller than 0.10% by weight, and the amount of surface Li2CO3 is smaller than 0.25% by weight; in an X-ray diffraction pattern, the ratio of an integral intensity of the (003) plane of the lithium metal composite oxide to that of the (104) plane thereof is higher than 1.15; and the amount of S obtained by a measurement using ICP is smaller than 0.10% by weight of the lithium metal composite oxide powder (100% by weight).