Multiphase Lithium-Ion Cathode Material for Thermal Stability
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Solution Overview
Problem
Current lithium-ion battery cathode materials face challenges with thermal stability and rate performance, particularly the spinel material's capacity degradation at elevated temperatures and lower capacity compared to layered oxides.
Innovation Solution
Development of a cathode active material with multiphase structures, specifically a compound with the formula Li1-a[NixCoyMz]O2-wGw, combining hexagonal and spinel structures, where M includes elements like Mn, Al, and others, and a method involving heating a metal-containing precursor with a lithium salt to create a stable multiphase structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If spinel material is used as cathode material, then rate capability is improved, but capacity is reduced and capacity degradation occurs at elevated temperature
Solution Approach 1:
The patent employs a composite cathode material comprising both spinel phase (LiM2O4) and layered phase (LiMO2) components. The spinel phase provides superior rate capability and thermal stability, while the layered phase contributes higher capacity. This composite structure resolves the contradiction by combining materials with complementary properties, allowing the cathode to achieve both fast charging/discharging rates and good capacity retention at elevated temperatures.
2Quantity of substance
If layered oxide material is used as cathode material, then capacity is improved, but rate capability is reduced
Solution Approach 1:
The composite cathode material combines layered oxide (providing high capacity) with spinel phase (providing fast ion transport). The layered structure offers higher lithium storage capacity, while the spinel component provides three-dimensional diffusion pathways that enhance rate capability. This composite approach allows the material to achieve both high capacity and fast charging/discharging performance.
Solution Approach 2:
The cathode material exhibits local structural differentiation where different phases are distributed throughout the structure. The layered regions provide high capacity zones, while spinel regions provide fast ion transport channels. This local quality variation allows different parts of the material to perform specialized functions, resolving the capacity-rate capability trade-off.
3Temperature
If spinel material is used as cathode material, then thermal stability is improved, but capacity degradation occurs at elevated temperature
Solution Approach 1:
The composite cathode material leverages the thermal stability of the spinel phase while mitigating its capacity degradation issue at elevated temperatures through the presence of the layered phase. The spinel component provides structural stability and thermal resistance, while the layered component maintains capacity performance. This composite strategy allows the material to withstand elevated temperatures without significant capacity loss.
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 multiphase cathode material demonstrates improved thermal stability and rate performance, maintaining capacity retention and superior cycling ability at elevated temperatures compared to conventional materials.
Implementation Method 1
heating a metal-containing precursor with a lithium salt to create a stable multiphase structure
Data Source
AI summary
A lithium deficient cathode active material for lithium-ion batteries is described. More particularly, the lithium deficient cathode active material can have multiphase structures, including both a layered or hexagonal structure (e.g., having an R-3m space group) and a spinel structure (e.g., having a Fd-m space group). Batteries including the cathode active material and methods of preparing the cathode active material are also described.