Al-P Coated High-Nickel Cathode Material for Stable Li-Ion Cycling
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Solution Overview
Problem
The demand for large-sized, high-capacity, or high-energy-density rechargeable lithium batteries has increased, but the supply of cobalt-based positive electrode active materials is limited due to the high cost and scarcity of cobalt, necessitating the development of cobalt-free or low-cobalt positive electrode active materials.
Innovation Solution
A positive electrode active material is developed, comprising core particles with a layered lithium nickel-manganese-based composite oxide and a coating layer containing Al and P, which improves the material's stability and performance at high temperatures and voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If cobalt-based positive electrode active materials are used to achieve high energy density, then battery performance is improved, but production cost increases and material scarcity becomes a problem
Solution Approach 1:
The patent changes the chemical composition parameters of the positive electrode active material by reducing cobalt content from traditional high levels to 0.5-5 mol%, and adjusting nickel content to 60-80 mol% and manganese content to 10-30 mol%. This parameter optimization maintains high energy density while reducing cobalt dependency and production cost
Solution Approach 2:
The patent creates a composite positive electrode active material with a layered lithium nickel-manganese-based composite oxide as the core and an aluminum-phosphorus coating layer. This composite structure combines the high capacity of nickel-based materials with the stability provided by the coating layer, achieving high energy density without requiring high cobalt content
2Quantity of substance
If high nickel content is used to increase capacity, then battery capacity is improved, but material stability deteriorates
Solution Approach 1:
The patent applies different properties to different parts of the positive electrode active material: the core region has high nickel content (60-80 mol%) for high capacity, while the surface coating layer contains aluminum and phosphorus for enhanced stability. This local differentiation allows the bulk material to maximize capacity while the surface protects against degradation
Solution Approach 2:
The aluminum-phosphorus coating layer acts as an intermediary between the high-nickel core material and the electrolyte environment. This coating layer prevents direct contact and harmful reactions between the unstable high-nickel material and the electrolyte, thereby maintaining material stability while preserving the high capacity of the nickel-based core
3Speed
If operating temperature is increased to improve reaction kinetics, then charge/discharge rate is improved, but side reactions increase and cycle life decreases
Solution Approach 1:
The patent applies an aluminum-phosphorus coating layer beforehand on the surface of the positive electrode active material to cushion and prevent harmful side reactions. This pre-protective coating reduces electrolyte decomposition and gas generation even at elevated temperatures, thereby extending cycle life while allowing improved reaction kinetics
Data Source
AI summary
A positive electrode active material, a method of preparing the same, a positive electrode, and a rechargeable lithium battery including the positive electrode are provided. The positive electrode active material includes core particles and a coating layer on the surface of the core particles. The core particles include a layered lithium nickel-manganese-based composite oxide having a nickel content (e.g., amount) of greater than, or equal to, about 60 mol % based on 100 mol % of a total metal amount excluding lithium. The coating layer includes Al and P.