Composite Cathode Material for Fast-Charging Lithium Battery Life
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Solution Overview
Problem
Lithium nickel cobalt manganese oxide-based positive electrode materials in lithium secondary batteries experience degradation in life performance during fast charging due to overload, especially when nickel content is high, leading to reduced cycle life and efficiency.
Innovation Solution
A positive electrode material comprising a lithium cobalt oxide and a lithium nickel cobalt manganese oxide, where the latter is prepared using a solid-phase method to control its electrical conductivity within a specific range (0.1 µS/cm to 150 µS/cm) and mixed with lithium cobalt oxide in a specific weight ratio, enhancing charge resistance and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium nickel cobalt manganese oxide is used as positive electrode active material to reduce cost and increase capacity, then cost competitiveness and energy density are improved, but life performance is degraded due to overload during fast charging
Solution Approach 1:
The positive electrode active material is segmented into two distinct components: lithium cobalt composite metal oxide (providing stable voltage and charge efficiency) and lithium nickel cobalt manganese oxide (providing capacity and cost benefits). This segmentation allows each material to perform its optimal function without the other's drawbacks, resolving the contradiction between capacity and life performance
Solution Approach 2:
The electrical conductivity of lithium nickel cobalt manganese oxide is controlled within a specific range (0.1 μS/cm to 150 μS/cm) through compositional adjustments and solid-phase preparation methods. This parameter control prevents excessive current uptake during fast charging, thereby improving life performance while maintaining capacity benefits
2Quantity of substance
If high content of nickel is included in lithium nickel cobalt manganese oxide to increase capacity, then energy density is improved, but life performance is further degraded due to increased overload susceptibility
Solution Approach 1:
The nickel content in lithium nickel cobalt manganese oxide is optimized within specific ranges (0.3 ≤ b < 0.8) while adjusting cobalt and manganese contents accordingly. This compositional parameter change balances capacity enhancement with overload resistance, preventing excessive degradation during fast charging
Solution Approach 2:
Lithium nickel cobalt manganese oxide is used as a composite material combining multiple metal elements (Ni, Co, Mn) in specific ratios. This composite structure leverages the advantages of each element: nickel for capacity, cobalt for stability, and manganese for cost and structural support, resolving the contradiction between high nickel content benefits and overload susceptibility
3Productivity
If lithium cobalt composite metal oxide is used to achieve high operating voltage and fast charging capability, then charge efficiency is improved, but manufacturing cost increases due to expensive cobalt
Solution Approach 1:
The positive electrode active material merges two compounds: lithium cobalt composite metal oxide (LiCo 1-a M a O 2) and lithium nickel cobalt manganese oxide (Li(Ni b Co c Mn d ) 1-x M 2 x O 2). This combination allows the system to achieve the charge efficiency of cobalt-based materials while reducing overall cobalt content through the nickel-cobalt-manganese component, thereby lowering manufacturing cost
Solution Approach 2:
Lithium nickel cobalt manganese oxide, which is cheaper than pure lithium cobalt oxide, is incorporated into the composite positive electrode active material. This substitution reduces the amount of expensive cobalt required while maintaining adequate charge efficiency, addressing the cost barrier
Data Source
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AI summary
The present invention relates to a positive electrode material, a method for manufacturing the same, a positive electrode for a lithium secondary battery and a lithium secondary battery comprising the same. According to the present invention, the positive electrode material comprises: a first positive active material represented by chemical formula 1 below and a second positive active material represented by chemical formula 2 below, wherein the positive electrode material has an electrical conductivity of 0.1 µS/cm to 150 µS/cm, which is measured after compressing the second positive active material with a rolling density of 400kgf to 2,000 kgf and manufacturing the second positive active material in the form of a pellet. [Chemical formula 1] LiCo1-aM1aO2 wherein, M1 is at least one selected from the group consisting of Al, Ti, Mg, and Zr, and 0≤a≤0.2 [Chemical formula 2] LiNibCocMndM2eO2 wherein, M2 is at least one selected from the group consisting of Al, Ti, Mg, Zr, Y, Sr, and B, and 0<b≤0,6, 0<c≤0,35, 0<d≤0,35 and 0<e≤0,1