Cathode Active Material Stabilizing Lithium Layer for Battery Lifespan
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional cathode active materials for lithium secondary batteries face challenges such as low structural stability, limited price competitiveness, and poor high-temperature characteristics, which affect their cycle and rate performance, especially in applications like electric vehicles that require long lifespan and high power density.
Innovation Solution
A cathode active material with a layered-crystal structure, specifically formulated with a transition metal layer containing less than 20% Li and a Ni cation mixing ratio of 1% to 4.5% in the lithium layer, which stabilizes the crystal structure by inserting Ni ions into the lithium layer, preventing structural collapse and enhancing cycle and rate characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiCoO2 is used as cathode active material, then charge/discharge efficiency and lifespan are improved, but structural stability deteriorates and cost increases due to cobalt resource limitation
Solution Approach 1:
The patent changes the compositional parameters by controlling Li content in transition metal layer to less than 20% and Ni cation mixing ratio to 1-4.5%, which stabilizes the layered crystal structure while maintaining charge/discharge efficiency. This parameter optimization resolves the contradiction between lifespan and structural stability.
Solution Approach 2:
The patent creates a composite cathode material with specific layered structure containing Li, Mn, Ni, and Co elements in controlled ratios. The composite structure combines the advantages of different elements to achieve both structural stability and long lifespan without relying solely on expensive cobalt.
2Quantity of substance
If LiNiO2-based cathode active material is used, then battery discharge capacity increases, but synthesis difficulty increases and rate characteristics deteriorate
Solution Approach 1:
The patent optimizes synthesis parameters by controlling sintering temperature (900-950°C) and time (10-20 hours) to achieve complete reaction and desired crystal structure. The controlled Li content and Ni mixing ratio enable simple solid phase reaction to produce high-capacity material with good rate characteristics.
3Object-affected harmful factors
If lithium manganese oxides are used, then thermal safety and cost are improved, but capacity and high-temperature characteristics deteriorate
Solution Approach 1:
The patent creates a composite material combining Li, Mn, Ni, and Co elements in a layered structure. This composite approach maintains the thermal safety of lithium manganese oxide while incorporating Ni and Co to enhance capacity and high-temperature characteristics, resolving the contradiction between safety and performance.
Solution Approach 2:
The patent introduces local compositional variations within the layered structure, with specific Li content in transition metal layer and controlled Ni cation mixing, to locally enhance capacity and high-temperature performance while maintaining overall thermal stability of the manganese oxide framework.
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 material achieves superior cycle stability, high capacity, and thermal stability, improving the performance of lithium secondary batteries, particularly in electric vehicles, by maintaining a well-grown layered structure and preventing structural collapse during charge/discharge cycles.
Implementation Method 1
a ratio of Ni positioned in a lithium layer, that is, a cation mixing ratio, in the layered-crystal structure, is 1% to 4.5%, based on a total amount of a lithium site in the lithium layer to stably support the layered-crystal structure
Implementation Method 2
lithium ions are intercalated and deintercalated between a mixed transition metal oxide layer
Data Source
AI summary
Disclosed is a cathode active material for secondary batteries comprising one or more compounds having a layered-crystal structure, represented by the following Formula 1, wherein a transition metal layer contains Li, in an amount lower than 20%, based on a total amount of a transition metal site, and a ratio of Ni positioned in a lithium layer, that is, a cation mixing ratio is 1% to 4.5%, based on a total amount of a lithium site in the lithium layer to stably support the layered-crystal structure: (1-s-t)[Li(LiaMn(1-a-x-y)NixCoy)O2]*s[Li2CO3]*t[LiOH] (1), wherein 0<a<0.2; 0<x<0.9; 0<y<0.5; a+x+y<1; 0<s<0.03; and 0<t<0.03. The cathode active material exhibits long lifespan and superior stability at room temperature and high temperatures in spite of repeated charge and discharge at a high current.