Dual-Layer Coated NCM Cathode for High-Temperature Stability
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Solution Overview
Problem
Ni-rich NCM ternary materials in lithium-ion batteries exhibit unstable surface structures and accelerated side reactions at the Ni-rich cathode/electrolyte interface due to high oxidative activity, impacting safety and performance.
Innovation Solution
A modified positive electrode active material is developed, comprising a substrate coated with a first oxide layer from elements like Li, Al, Zr, and a second oxide layer with a continuous structure from elements like Li, B, P, As, Pb, V, and Sn, which reduces side reactions and improves high-temperature storage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating layer is applied to the surface of Ni-rich NCM ternary material, then side reactions between the material and electrolyte are inhibited, but the coating is difficult to uniformly cover the surface
Solution Approach 1:
The coating is divided into two distinct layers: a first coating layer containing Ni-rich NCM ternary material particles, and a second coating layer containing oxide particles formed on the surface of the first layer. This segmentation allows each layer to perform its function optimally - the first layer provides the base structure while the second layer ensures uniform coverage and enhanced protection against side reactions.
Solution Approach 2:
The first coating layer is formed first as a preliminary step, providing a substrate for the subsequent formation of the second coating layer. This preliminary action ensures that the oxide particles in the second layer have a proper foundation to adhere to, achieving uniform coverage that would be difficult to obtain with a single-layer coating applied directly to the Ni-rich NCM ternary material.
2Ease of manufacture
If conventional coating methods are used, then the coating can be applied to the surface, but the coating has very limited inhibition effects on side reactions
Solution Approach 1:
The invention uses a composite coating structure where the first layer contains Ni-rich NCM ternary material particles and the second layer contains oxide particles (such as Al2O3, TiO2, ZrO2, or SiO2) formed on the first layer. This composite structure combines the benefits of the Ni-rich NCM ternary material with the protective properties of the oxide layer, achieving superior inhibition of side reactions compared to conventional single-material coatings.
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 modified material enhances structural stability, reduces gas production, improves safety and cycling performance, and extends the service life of lithium-ion batteries.
Implementation Method 1
mixing homogeneously a positive electrode active material substrate with first oxide layer itself or the precursor thereof followed by sintering, to coat the surface of the positive electrode active material substrate with the first oxide layer
Data Source
AI summary
The disclosure provides a modified positive electrode active material, a preparation method thereof, and an electrochemical energy storage device. The modified positive electrode active material comprises positive electrode active material substrate; first oxide layer, coated on the surface of the positive electrode active material substrate and selected from one or more of oxides of element M being selected from the group of one or more of Li, Al, Zr, Mg, Ti, Y, Si, Ca, Cr, Fe, Zn, Nb, Sn, Ba, and Cd; and second oxide layer having a continuous layered structure, coated on the surface of the first oxide layer and selected from one or more of oxides of element M′ being selected from one or more of Li, B, P, As, Pb, V, Mo, and Sn. High temperature storage performance and cycling performance of electrochemical energy storage device are improved by the modified positive electrode active material.