Composite Cathode Material for High-Power Lithium Battery
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Solution Overview
Problem
Lithium manganese composite oxide cathodes in secondary batteries suffer from manganese ion elution at high temperatures and high-current charge/discharge cycles, leading to degradation and limited service life, especially in electric vehicles, where high-energy density and safety are critical.
Innovation Solution
A cathode active material comprising a mixture of lithium/manganese spinel oxide and lithium/nickel/cobalt/manganese composite oxide with specific particle size and mixing ratios, along with potential manganese substitution, to enhance stability and safety, ensuring more than 70% capacity retention after 300 cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium manganese composite oxide is used as cathode material, then cost and safety are improved, but charge density is reduced compared to lithium cobalt or lithium nickel composite oxides
Solution Approach 1:
The patent creates a composite cathode combining lithium manganese spinel oxide with lithium nickel cobalt manganese oxide (LNCM). The LNCM component provides high charge density while the lithium manganese spinel oxide component maintains safety and prevents manganese elution, thus achieving both high charge density and safety simultaneously.
Solution Approach 2:
The patent employs a core-shell structure where the lithium manganese spinel oxide forms an outer layer protecting the inner LNCM core. This local quality differentiation allows the inner core to provide high charge density while the outer shell provides safety and prevents manganese ion elution.
2Power
If high-current charge/discharge cycles are repeated, then power output is improved, but manganese ion elution increases leading to degradation
Solution Approach 1:
The composite cathode material combines lithium manganese spinel oxide with LNCM, where the LNCM component provides high power output capability through fast ion transport while the lithium manganese spinel oxide component prevents manganese ion elution even under high-current conditions, thereby maintaining service life.
Solution Approach 2:
The patent increases the particle size to 15 μm or more, which reduces the surface area exposed to the electrolyte and minimizes manganese ion elution during high-current charge/discharge cycles. This parameter change allows high power output to be achieved without sacrificing service life.
Data Source
AI summary
Provided is a non-aqueous electrolyte-based, high-power lithium secondary battery having a long service life and superior safety at both room temperature and high temperature, even after repeated high-current charging and discharging. The battery comprises a cathode active material composed of a mixture of lithium/manganese spinel oxide and lithium/nickel/cobalt/manganese composite oxide wherein the cathode active material exhibits the life characteristics that the capacity at 300 cycles is more than 70% relative to the initial capacity, in the provision of satisfying the condition (i) regarding the particle size and the condition (ii) regarding the mixing ratio.