High-Ni NCM Positive Electrode With Metal Oxide Thermal Stabilization
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Solution Overview
Problem
High-Ni NCM-based lithium oxide positive electrodes in secondary batteries face limitations in thermal stability due to reduced structural and chemical stability as nickel content increases, particularly when exceeding 80 atm%, leading to rapid heat generation and safety concerns.
Innovation Solution
Incorporating a metal oxide with a lower binding potential to lithium within the positive electrode active material layer, specifically using metallic elements like molybdenum, vanadium, titanium, and tungsten, to delay heat generation and minimize calorific values, thereby enhancing thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high nickel content (80 at% or more) is used in the positive electrode active material to achieve high capacity, then capacity achievement is improved, but thermal stability is rapidly reduced due to deteriorated structural and chemical stability
Solution Approach 1:
The patent uses a composite material system consisting of high-Ni NCM (LiNi0.8Co0.075Mn0.075O2) as the primary active material combined with metal oxide coatings (such as Al2O3, TiO2, ZrO2, or Ta2O5) on the particle surfaces. This composite structure allows the core high-Ni material to provide high capacity while the oxide coating layer provides thermal stability and structural protection, resolving the contradiction between capacity and thermal stability.
Solution Approach 2:
The patent modifies the chemical composition parameters by incorporating metal oxides with specific properties (high melting point, low reactivity with electrolyte) as coatings. By changing the surface composition parameters and controlling the thickness of the coating layer (0.1-5 nm), the material achieves both high capacity retention and improved thermal stability, effectively managing the trade-off between capacity and safety.
2Stability of the object's composition
If metal oxide coating is applied to improve structural stability, then structural stability is improved, but sufficient thermal stability cannot be secured
Solution Approach 1:
The patent specifies precise parameter ranges for the metal oxide coating, including thickness (0.1-5 nm) and composition ratios, to optimize both structural and thermal stability. By carefully controlling these parameters, the coating provides sufficient thermal protection without compromising the underlying high-Ni active material's capacity, resolving the insufficiency of previous coating approaches.
Solution Approach 2:
The patent employs specific metal oxides (Al2O3, TiO2, ZrO2, Ta2O5) selected for their high melting points and chemical inertness, creating a composite structure where the oxide layer acts as a thermal barrier while maintaining electrical conductivity pathways. This specific composite material selection achieves sufficient thermal stability that previous generic coatings failed to provide.
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 inclusion of these metal oxides significantly increases self-heating time and reduces instantaneous calorific values, resulting in improved thermal stability and reduced risk of explosion, with self-heating time increased by 30% and instantaneous calorific values remaining 0.3 or less, demonstrating enhanced safety and performance.
Implementation Method 1
a metal oxide including a metallic element having a binding potential with lithium of 0.5 V to 4 V
Data Source
AI summary
A positive electrode for a secondary battery includes a positive electrode active material layer, which includes a positive electrode active material including a lithium transition metal oxide which contains nickel, cobalt, and manganese and has an atomic ratio of nickel in total transition metals of 80 atm % or more, and a metal oxide including a metallic element having a binding potential with lithium of 0.5 V to 4 V. A secondary battery including the positive electrode is also provided.