Composite Positive Electrode Material for Lithium Battery Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries for electric vehicles face challenges in achieving high energy density, long lifespan, and safety due to limitations in existing positive electrode active materials, such as LiCoO2's structural instability and LiNiO2's safety issues under charge and discharge, as well as the inefficiencies of lithium manganese oxides.
Innovation Solution
A positive electrode active material represented by Formula 1, including specific elements like Ru and transition metals, is developed to maintain structural stability at high voltages, preventing oxygen escape and enhancing capacity and rate characteristics, while being cost-effective by avoiding expensive cobalt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiCoO2 is used as positive electrode active material, then lifetime characteristics and charge-discharge efficiency are improved, but structural stability deteriorates and cost increases
Solution Approach 1:
The patent uses a composite material system consisting of Li2MnO3 layered structure combined with spinel LiMn2O4. This composite structure integrates the advantages of both materials: the layered Li2MnO3 provides high capacity and voltage, while the spinel LiMn2O4 provides structural stability. The coexistence of these two phases in a single crystal structure prevents the structural instability issues of pure LiCoO2 while maintaining high performance.
2Quantity of substance
If LiNiO2 is used to reduce cost and increase capacity, then discharge capacity improves, but safety deteriorates due to phase transition
Solution Approach 1:
The patent creates a composite structure where Li2MnO3 layered phase and spinel LiMn2O4 phase coexist. The spinel phase acts as a structural buffer that prevents abrupt phase transitions during charge-discharge cycles, thereby maintaining safety while the Li2MnO3 phase provides high discharge capacity. This composite approach eliminates the safety issues of pure LiNiO2 without sacrificing capacity.
3Reliability
If lithium manganese oxide is used for thermal safety and cost, then safety improves, but charge capacity deteriorates
Solution Approach 1:
The patent combines Li2MnO3 layered structure with spinel LiMn2O4 to create a composite material. The Li2MnO3 phase provides high charge capacity (exhibiting capacity of 270 mAh/g or more at 4.5V), while the spinel LiMn2O4 phase maintains thermal stability and structural integrity. This composite structure overcomes the low capacity limitation of pure lithium manganese oxide.
4Quantity of substance
If oxide with excessive lithium is used to achieve high capacity at high voltage, then charge capacity improves, but structural stability deteriorates due to oxygen escape
Solution Approach 1:
The patent designs a composite structure where Li2MnO3 layered phase coexists with spinel LiMn2O4 phase. The spinel phase acts as a structural stabilizer that prevents oxygen escape and structural collapse during high-voltage activation. This allows the Li2MnO3 phase to fully utilize excess lithium for high capacity (270 mAh/g or more at 4.5V) without suffering from the structural instability that would otherwise occur.
Data Source
AI summary
Disclosed herein are a positive electrode active material including at least one selected from among compounds represented by Formula 1 below and a lithium secondary battery including the same that is capable of improving lifetime characteristics and rate characteristics while exhibiting excellent safety: Li[LixMyM′(1-x-y)]O2-zAz (1), where M is at least one element selected from a group consisting of Ru, Mo, Nb, Te, Re, Ir, Pt, Cr, S, W, Os, and Po, M′ is at least one element selected from a group consisting of Ni, Ti, Co, Al, Mn, Fe, Mg, B, Cr, Zr, Zn, and second row transition metals, A is a negative monovalent or divalent anion, and 0<x<0.3, 0.2≤y≤0.5, 0≤z<0.5, and 0.2<x+y<0.8.