Cathode Active Material Composition for Cobalt-Reduced Li-Ion Batteries
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Solution Overview
Problem
Lithium secondary batteries face limitations in increasing energy density and high output performance due to the high cost and instability of cobalt-based materials, and the low capacity and efficiency of graphite-based negative electrodes.
Innovation Solution
A composition for a positive electrode active material layer using a lithium composite transition metal compound with high nickel content, combined with a specific additive represented by Chemical Formula A, and a silicon-based oxide as the negative electrode material to enhance energy density and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cobalt-based positive electrode active material is used, then high operating voltage and excellent capacity characteristics are achieved, but rising prices and unstable supply of cobalt limit large-scale usage
Solution Approach 1:
The patent changes the compositional parameters of the positive electrode active material by substituting cobalt with nickel and manganese in specific ratios (Ni: 30-80 mol%, Co: 10-50 mol%, Mn: 10-50 mol%). This parameter change allows maintaining high capacity characteristics while reducing dependence on cobalt, thereby resolving the contradiction between reliability and quantity of substance.
Solution Approach 2:
The patent creates a composite nickel-cobalt-manganese lithium oxide material that combines the advantages of different metals. The composite structure enables high operating voltage from cobalt, high capacity from nickel, and improved thermal stability from manganese, resolving the contradiction by distributing functions across multiple elements.
2Quantity of substance
If nickel content in NCM-based lithium composite transition metal oxide is increased to increase capacity, then capacity is improved, but resistance increases and thermal stability deteriorates causing increased gas generation
Solution Approach 1:
The patent optimizes the nickel content parameter within a specific range (30-80 mol%) rather than maximizing it. This parameter change balances capacity improvement with thermal stability maintenance. Additionally, the patent controls the ratio between nickel and manganese to prevent excessive resistance and gas generation while maintaining high capacity.
Solution Approach 2:
The patent applies different elemental compositions to different functional requirements within the same material system. Nickel is concentrated in regions responsible for capacity, while manganese is distributed to maintain thermal stability and reduce resistance. This local quality differentiation resolves the contradiction between capacity and thermal stability.
3Reliability
If graphite is used as negative electrode active material, then good initial efficiency is achieved, but small capacity per unit mass (372 mAh/g) limits battery capacity increase
Solution Approach 1:
The patent merges graphite with silicon-based materials in the negative electrode. Graphite provides good initial efficiency and structural stability, while silicon-based materials contribute high capacity per unit mass. This combination resolves the contradiction by integrating the advantages of both materials into a unified electrode system.
Solution Approach 2:
The patent creates a composite negative electrode using graphite and silicon-based materials. The composite structure enables the battery to achieve both good initial efficiency from graphite and high capacity per unit mass from silicon, thereby resolving the contradiction between reliability and quantity of substance.
4Quantity of substance
If non-carbon-based negative electrode materials (silicon, tin, oxides) are used to increase capacity, then large capacity is achieved, but large amount of lithium is consumed and irreversible capacity loss increases due to low initial efficiency
Solution Approach 1:
The patent merges non-carbon-based materials (silicon, tin, or oxides) with graphite in the negative electrode. The non-carbon-based materials provide large capacity, while graphite maintains good initial efficiency and reduces irreversible capacity loss. This merging resolves the contradiction between capacity and energy loss.
Solution Approach 2:
The patent creates a composite negative electrode structure where non-carbon-based materials are combined with graphite or carbon coatings. This composite approach enables achieving large capacity from silicon/tin/oxides while maintaining low irreversible capacity loss through the graphite component, thereby resolving the contradiction between quantity of substance and loss of energy.
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 increases energy density, improves high output performance, and enhances battery cycle performance while maintaining stability and efficiency, reducing the reliance on cobalt and improving the efficiency matching between positive and negative electrodes.
Implementation Method 1
The lithium secondary battery generates electric energy by oxidation and reduction reactions during intercalation and deintercalation of lithium ions
Data Source
AI summary
The present disclosure relates to a composition for a positive electrode active material layer of a lithium secondary battery, including a positive electrode active material including a lithium composite transition metal compound which includes nickel, cobalt and manganese and includes 80 mol % or more and less than 100 mol % of nickel among the metals except for lithium and an additive represented by Chemical Formula A. The present disclosure also relates to a positive electrode, a lithium secondary battery, a battery module, and a battery pack, all of which including the disclosed positive electrode active material layer.