Lanthanide-Coated Monocrystalline Cathode for Lithium Battery
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Solution Overview
Problem
Lithium secondary batteries with high energy density face safety concerns and reduced lifespan due to particle aggregation, reduced productivity, increased residual lithium, and decreased capacity and rate capability in the preparation of monocrystalline cathode active materials.
Innovation Solution
A composite cathode active material with a nickel-based active material containing 60 mol% or more nickel, coated with a lanthanide composite, is prepared through a method involving heat-treatments and mechanical milling, which includes a lanthanide precursor in specific weight ratios and heat-treatment conditions to form monocrystalline particles with improved lithium diffusion and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a monocrystalline cathode active material is prepared using related art methods, then lifespan characteristics are improved, but particle aggregation occurs and productivity decreases
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the core maintains monocrystalline structure for lifespan improvement while the shell consists of aggregated particles for better productivity. The cathode active material includes monocrystalline particles covered by a coating layer, creating distinct functional zones that resolve the contradiction between lifespan and productivity
2Reliability
If a monocrystalline cathode active material is prepared using related art methods, then lifespan characteristics are improved, but residual lithium increases and capacity decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the amount of lithium precursor (mixing molar ratio Li/Me of 0.2-0.4 in first mixture, 0.8-1.2 in second mixture) and heat treatment temperatures (600-1200°C for first heat treatment, 700-900°C for second heat treatment) to optimize the balance between lifespan and capacity, reducing residual lithium while maintaining monocrystalline structure benefits
3Use of energy by moving object
If high energy density is achieved in lithium secondary batteries, then energy density improves, but safety decreases
Solution Approach 1:
The patent applies composite materials by creating a composite cathode active material consisting of monocrystalline nickel-based particles coated with a specific coating layer. This composite structure enables high energy density through the nickel-based active material while the coating layer provides safety by suppressing particle aggregation and stabilizing the crystal structure during charging and discharging
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 composite cathode active material enhances the safety, rate capability, and lifespan of lithium secondary batteries by suppressing particle aggregation, reducing side reactions, and maintaining stable crystal structure during charging and discharging.
Implementation Method 1
a first heat-treatment on the first mixture in an oxidizing gas atmosphere to obtain a nickel-based lithium metal oxide
Implementation Method 2
performing a first heat-treatment on the first mixture in an oxidizing gas atmosphere
Implementation Method 3
maintaining stable crystal structure during charging and discharging
Data Source
AI summary
A composite cathode active material, a method of preparing the composite cathode active material, and a lithium secondary battery including a cathode including the composite cathode active material are provided. The composite cathode active material includes: a nickel-based active material including about 60 mol % or more of nickel; and a coating layer on a surface of the nickel-based active material, the coating layer including a lanthanide composite. The composite cathode active material includes or is in the form of single crystal particles having an average particle diameter in a range of about 2 μm to about 8 μm.