Composite Electrode Active Material for High-Voltage Lithium Secondary Batteries
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Solution Overview
Problem
Lithium secondary batteries face challenges with lithium-containing cobalt oxides due to safety concerns, resource limitations, and high costs, while lithium manganese oxides suffer from poor cycle characteristics and electrolyte decomposition, limiting their energy density and stability.
Innovation Solution
A composite electrode active material with specific molar ratios of lithium to metals and manganese, combined with conductive coatings and particle shapes, is used to enhance high-voltage stability and energy density in lithium secondary batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium-containing cobalt oxides (LiCoO2) are used as positive electrode active materials, then excellent cycle properties and overall physical properties are achieved, but safety is low and cost is high due to resource limitations
Solution Approach 1:
A coating layer comprising at least one of a metal oxide, metal hydroxide, metal carbonate, or metal oxyhydroxide is applied to the surface of the lithium-containing cobalt oxide particles. This coating layer acts as an intermediary between the LiCoO2 and the electrolyte solution, preventing direct harmful interactions while maintaining the excellent cycle properties of LiCoO2, thereby improving safety without sacrificing reliability
Solution Approach 2:
The invention changes the surface parameters of LiCoO2 particles by applying a coating layer with specific composition and thickness (0.1-10 μm). This parameter change modifies the surface chemistry and stability, improving safety characteristics while preserving the bulk material's excellent cycle properties
2Ease of manufacture
If lithium manganese oxides (LiMnO2, LiMn2O4) are used as positive electrode active materials, then cost is reduced and environmental friendliness is improved, but cycle characteristics are poor and electrolyte decomposition occurs at high temperatures
Solution Approach 1:
A coating layer comprising metal oxide, metal hydroxide, metal carbonate, or metal oxyhydroxide is applied to the surface of lithium manganese oxide particles. This coating layer acts as a protective intermediary that prevents electrolyte decomposition and manganese elution at high temperatures, thereby improving cycle characteristics while maintaining the cost and environmental advantages of manganese-based materials
Solution Approach 2:
The invention creates a composite structure by combining lithium manganese oxide core particles with a protective coating shell. This composite material approach leverages the cost and environmental benefits of manganese oxides while adding the stability and protective properties of the coating layer, resulting in improved cycle characteristics
3Stability of the object's composition
If Li2MnO3 is used as positive electrode active material, then structural stability is excellent, but electrochemical activity is poor due to inactivity at normal operating voltages
Solution Approach 1:
The invention changes the surface parameters of Li2MnO3 particles by applying a coating layer that facilitates electrochemical reactions. The coating layer modifies the surface chemistry to enable ion and electron transport while preserving the bulk structural stability of Li2MnO3, thereby activating electrochemical activity without compromising structural integrity
Data Source
AI summary
Disclosed are an electrode active material having improved energy density and a lithium secondary battery including the same. More particularly, provided is an electrode active material including a first electrode active material and a second electrode active material, each of the first electrode active material and the second electrode active material having a composition represented by Formula (1) below, a ratio of lithium to metals in the first electrode active material being 1.4 to 1.7, and a ratio of lithium to metals in the second electrode active material being 1.2 or more and less than 1.4:(1−x)LiM′O2−yAy−xLi2MnO3−y′Ay′ (1)wherein M′ is MnaMb; M is at least one selected from the group consisting of Ni, Ti, Co, Al, Cu, Fe, Mg, B, Cr, Zr, Zn and Period II transition metals; A is at least one selected from the group consisting of anions such as PO4, BO3, CO3, F and NO3; 0<x<1; 0<y≤0.02; 0<y′≤0.02; 0.5≤a≤1.0; 0≤b≤0.5; and a+b=1.