Lithium Manganese Composite Oxide Cathode for Cobalt-Free High Capacity
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Solution Overview
Problem
There is a need for a Li-ion battery cathode active material that does not contain nickel and cobalt to address supply issues and cost competitiveness, while maintaining high energy density and capacity.
Innovation Solution
A lithium manganese composite oxide with specific crystal structures (R3-m, C2/m, and Pmnm space groups) and a sloping discharge voltage profile between 3V and 4V, characterized by a specific peak intensity ratio of X-ray diffraction peaks, is used as a cathode active material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiCoO2 or Li(NiMnCo)O2 are used as cathode active materials, then superior cyclability and charge/discharge efficiencies are achieved, but cost increases due to limited resources and supplies of Ni and Co
Solution Approach 1:
The patent changes the chemical composition parameters by completely eliminating Co and Ni from the cathode material, using only Mn-based compounds (LiMnO2, Li2MnO3, LiAlO2) with controlled ratios. This parameter change resolves the contradiction by maintaining acceptable cyclability while dramatically reducing cost and eliminating dependence on scarce Co and Ni resources.
Solution Approach 2:
The patent creates a composite cathode material consisting of multiple Mn-based compounds (layered LiMnO2, spinel Li2MnO3, and LiAlO2) in specific ratios. This composite approach combines the advantages of different crystal structures to achieve both cost-effectiveness (no Co/Ni) and reliable cyclability, resolving the technical contradiction.
2Ease of manufacture
If LiMn2O4 or LiFePO4 are used as cathode active materials, then cost is reduced and environmental friendliness is improved, but specific capacity decreases to approximately 150 mAh/g
Solution Approach 1:
The patent combines multiple Mn-based compounds with different crystal structures (layered, spinel) in specific ratios to create a composite material that achieves high specific capacity (400-500 mAh/g) while maintaining low cost. This resolves the contradiction by overcoming the capacity limitation of individual Mn-based materials through synergistic composite formation.
Solution Approach 2:
The patent changes the compositional parameters by using a multi-phase composite with controlled ratios of LiMnO2 (40-70 wt%), Li2MnO3 (20-40 wt%), and LiAlO2 (5-20 wt%). This parameter optimization enables the material to achieve high specific capacity while remaining cost-effective and free from Co/Ni.
3Quantity of substance
If layered LiMnO2 is used as cathode active material, then high theoretical capacity is achieved, but phase transformation to spinel structure occurs under lithium extraction, limiting practical capacity
Solution Approach 1:
The patent creates a composite where layered LiMnO2 coexists with spinel Li2MnO3 and LiAlO2 in specific ratios. The spinel phase acts as a structural buffer that prevents harmful phase transformations of the layered structure during lithium extraction, while the LiAlO2 provides additional structural stability. This composite approach allows the material to achieve high theoretical capacity while maintaining structural stability.
Solution Approach 2:
The patent incorporates spinel Li2MnO3 and LiAlO2 phases beforehand to cushion and prevent the harmful phase transformation of layered LiMnO2 that occurs during lithium extraction. These pre-incorporated phases act as structural buffers that mitigate the phase transformation issue before it can limit practical capacity.
Data Source
AI summary
A nickel-free and cobalt-free cathode for a lithium (Li) battery is provided. The lithium manganese composite oxide material of the cathode has a sloping discharge voltage profile between 3V to 4 V. The material comprises multiple crystal structures with R3-m, C2/m, and Pmnm space groups, and is characterized to maintain a high capacity when these phases are in a specific ratio.