Lithium-Manganese Composite Oxide for High-Capacity Battery Anodes
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Solution Overview
Problem
Current lithium-ion secondary batteries face challenges with high production costs due to the use of expensive cobalt in positive electrode active materials, limited lithium ion capacity, and inadequate ion and electron conductivity, which hinder achieving high energy density and reliability.
Innovation Solution
A lithium-manganese composite oxide with a layered rock-salt or spinel crystal structure is developed, incorporating metals like nickel, which allows for increased lithium ion capacity, high ion and electron conductivity, and reduced production costs through a simple synthesis process involving ball milling and high-temperature firing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If LiCoO2 is used as positive electrode active material, then high capacity and energy density are achieved, but production cost increases due to expensive cobalt
Solution Approach 1:
The patent substitutes expensive cobalt with cheaper manganese-based materials (LiMn2O4 spinel and Li2MnO3 layered rock-salt) to reduce production cost while maintaining acceptable battery performance and cycle life
Solution Approach 2:
The patent creates a composite structure by coating Li2MnO3 particles with LiMn2O4 spinel layer, combining the high capacity advantage of layered rock-salt structure with the high conductivity advantage of spinel structure to achieve both cost reduction and performance maintenance
2Quantity of substance
If Li2MnO3 with layered rock-salt structure is used, then cost is reduced and capacity is increased, but ion conductivity and electron conductivity decrease
Solution Approach 1:
The patent forms a composite where Li2MnO3 particles are coated with LiMn2O4 spinel, combining the high capacity of layered rock-salt structure with the high conductivity of spinel structure to resolve the conductivity deficiency
Solution Approach 2:
The patent applies different functional properties to different parts of the composite material: the inner Li2MnO3 core provides high capacity while the outer LiMn2O4 spinel shell provides high ion and electron conductivity, allowing each region to optimize its local function
3Reliability
If LiMn2O4 with spinel structure is used, then ion conductivity and electron conductivity are improved, but lithium ion capacity is limited
Solution Approach 1:
The patent creates a core-shell composite where the LiMn2O4 spinel outer layer provides high conductivity while the Li2MnO3 layered rock-salt core provides high lithium ion capacity, achieving both conductivity improvement and capacity enhancement simultaneously
Data Source
AI summary
The amount of lithium ions that can be received and released in and from a positive electrode active material is increased, and high capacity and high energy density of a secondary battery are achieved. Provided is a lithium-manganese composite oxide represented by LixMnyMzOw, where M is a metal element other than Li and Mn, or Si or P, and y, z, and w satisfy 0≦̸x/(y+z)<2, y>0, z>0, 0.26≦̸(y+z)/w<0.5, and 0.2<z/y<1.2. The lithium manganese composite oxide has high structural stability and high capacity.