Coated High-Nickel Cathode Material for High-Voltage Cycle Life
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Solution Overview
Problem
The increasing demand for high-capacity, high-energy-density rechargeable lithium batteries is hindered by the scarcity and high cost of cobalt, and existing cobalt-free materials face challenges in maintaining structural stability, capacity, and high-voltage performance due to side reactions with electrolytes.
Innovation Solution
A positive electrode active material comprising a mixture of lithium nickel-manganese composite oxide secondary particles and single particles, coated with specific amounts of aluminium and yttrium, enhances structural stability and suppresses side reactions, achieving high capacity and long cycle-life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If cobalt-based positive electrode active materials are used, then high capacity and high energy density are achieved, but production cost increases and supply security deteriorates
Solution Approach 1:
The patent extracts cobalt from the positive electrode active material composition, developing cobalt-free lithium nickel-manganese composite oxide materials. This removes the expensive and scarce cobalt element while maintaining the electrochemical performance through optimized nickel-manganese combinations and surface coating strategies
Solution Approach 2:
The patent employs composite material strategies by combining lithium nickel-manganese composite oxide with specific surface coatings containing aluminum, magnesium, and other elements. This composite approach maintains high capacity and energy density while eliminating cobalt dependency
2Quantity of substance
If nickel content is increased to achieve high capacity, then energy density improves, but side reactions with electrolyte increase at high voltage
Solution Approach 1:
The patent applies local quality modification by implementing surface coatings on the lithium nickel-manganese composite oxide particles. The coatings are strategically applied only at the particle surfaces where electrolyte contact occurs, providing localized protection against side reactions while preserving the high-nickel core's capacity-generating properties
Solution Approach 2:
The patent introduces surface coating layers containing aluminum, magnesium, and other elements as intermediary barriers between the high-nickel active material and the electrolyte. These intermediary layers prevent direct contact and harmful side reactions while allowing ionic transport, thus protecting the high-voltage performance
Data Source
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AI summary
A positive electrode active material includes: a first positive electrode active material including a lithium nickel-manganese composite oxide having a nickel content of at least about 60 mol% based on a total metal excluding lithium and being in a form of secondary particles each including a plurality of primary particles; and a second positive electrode active material including a lithium nickel-manganese-based composite oxide having a nickel content of at least about 60 mol% based on a total metal excluding lithium and being in a form of single particles and a coating layer on the surface of the single particle and containing aluminium and yttrium, an aluminium content of the coating layer being about 0.1 mol% to about 2 mol% and an yttrium content of the coating layer being about 0.1 mol% to about 1 mol%, based on a total metal excluding lithium in the second positive electrode active material.