Lithium Nickel Composite Oxide Cathode for High Capacity and Stability
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Solution Overview
Problem
Current lithium nickel composite oxide positive electrode materials for lithium secondary batteries lack satisfactory electrode density and capacity, limiting their cyclic stability and longevity.
Innovation Solution
A composite precursor represented by Formula 1 (aMn3O4-bM(OH)2) is mixed with a lithium compound and heat-treated to form a composite represented by Formula 2 (aLi2MnO3-bLiyMO2), which improves the cycle life properties by forming a uniform Li2MnO3 phase, enhancing electrode density and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium nickel composite oxide is used as positive electrode active material, then battery capacity is improved, but electrode density and cyclic stability deteriorate
Solution Approach 1:
The patent uses a composite precursor consisting of spinel Mn3O4 and metal hydroxide M(OH)2 mixed in specific molar ratios. This composite structure combines the advantages of both materials: Mn3O4 provides high capacity while the metal hydroxide component enhances structural stability during cycling. The composite precursor is then heat-treated to form a composite oxide that maintains both high capacity and improved cyclic stability, directly resolving the contradiction between capacity and reliability.
Solution Approach 2:
The patent introduces transition metals (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Al, Mg, Zr, or B) at specific positions in the lithium nickel composite oxide structure. These transition metals are added in controlled amounts (0.01-0.5 mol each) to locally enhance structural stability and reduce degradation. This local modification approach maintains the overall high capacity of lithium nickel composite oxide while improving cyclic stability through localized structural reinforcement.
2Reliability
If transition metal is added to lithium nickel composite oxide, then stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent prepares a composite precursor containing both Mn3O4 and metal hydroxide in specific ratios before heat treatment. This preliminary preparation ensures that the transition metals are pre-positioned and uniformly distributed in the precursor structure. During subsequent heat treatment, the composite precursor transforms into the final composite oxide with properly distributed transition metals, simplifying the manufacturing process by eliminating the need for multiple separate doping steps and ensuring uniform composition.
Solution Approach 2:
The patent optimizes the molar ratio parameters of Mn3O4 to M(OH)2 in the composite precursor (specific ratios of 1:1, 2:1, or 1:2) and controls the heat treatment temperature and atmosphere parameters. By optimizing these parameters, the patent achieves stable lithium nickel composite oxide with transition metal doping while maintaining relatively simple manufacturing conditions. The parameter optimization ensures that the transition metals are effectively incorporated without requiring excessively complex processing conditions.
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 resulting lithium secondary battery exhibits improved cycle life and capacity maintenance, with the composite precursor's heat treatment process optimizing the lithium composite oxide's properties for better performance.
Implementation Method 1
the composite represented by Formula 2 is prepared by mixing the composite precursor of Formula 1 and a lithium compound, and then heat-treating the mixture
Data Source
AI summary
A composite precursor represented by Formula 1, a composite prepared therefrom represented by Formula 2, a method of preparing a composite precursor and a composite, a positive electrode for lithium secondary battery including the same, and a lithium secondary battery employing the same.aMn3O4-bM(OH)2 Formula 1wherein in Formula 1, 0<a≦0.8, 0.2≦b<1and M is at least one metal selected from the group consisting of titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron, (Fe), cobalt (Co), nickel (Ni), copper (Cu), aluminum (Al), magnesium (Mg), zirconium (Zr), and boron (B)aLi2MnO3-bLiyMO2 Formula 2wherein in Formula 2, 0≦a≦0.6, 0.4≦b≦11.0≦y≦1.05,and M is at least one metal selected from the group consisting of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Al, Mg, Zr, and B.