Lithium Manganese Cathode Stabilization via Li3PO4 Coating
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Solution Overview
Problem
Lithium manganese composite oxides used in lithium secondary batteries for electric vehicles suffer from manganese release at high temperatures, leading to battery property deterioration and low capacity per unit weight, necessitating additional costly processes for stabilization.
Innovation Solution
A cathode with a transition metal layer containing lithium, specifically formulated as (1-x)Li(Li y M 1-y-z Ma z )O 2-w A w * xLi 3 PO 4, where M is Al, Mg, or B, A is a halogen or chalcogenide, and Li 3 PO 4 enhances ion conductivity and bonding, stabilizing the crystal structure without requiring additional processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium manganese composite oxide is used as cathode material, then cost is reduced and safety is improved, but manganese is released into electrolyte at high temperature causing battery property deterioration
Solution Approach 1:
A coating layer comprising Li3PO4 and a lithium transition metal oxide is applied on the surface of the lithium manganese composite oxide particles. This coating layer acts as an intermediary barrier that prevents direct contact between manganese and the electrolyte, thereby preventing manganese dissolution while maintaining the electrochemical performance and safety benefits of lithium manganese composite oxide.
2Reliability
If lithium manganese composite oxide is used as cathode material, then cost is reduced, but capacity per unit weight is lower compared to lithium cobalt or lithium nickel composite oxides
Solution Approach 1:
The cathode active material is formulated as a composite system combining lithium manganese composite oxide (Li1-x-yMnxBryO2) with surface coating materials (Li3PO4 and lithium transition metal oxide). This composite structure leverages the cost advantage of manganese-based materials while the surface coating enhances overall performance, achieving a balance between cost-effectiveness and capacity.
3Stability of the object's composition
If surface treatment is applied to lithium manganese composite oxide, then stability is improved, but manufacturing complexity and cost increase due to additional processes
Solution Approach 1:
The coating layer is formed by combining Li3PO4 and lithium transition metal oxide in a single integrated structure that is applied directly to the cathode particles. This merged coating approach provides dual functionality (preventing manganese dissolution and maintaining structural stability) in one process step, avoiding the need for multiple sequential treatments and reducing manufacturing complexity.
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 formulation significantly improves cycle and storage properties, reducing capacity deterioration and maintaining performance over extended cycles, making it suitable for high-temperature applications in electric vehicles.
Implementation Method 1
Li 3 PO 4 having a strong bonding force and ion conductivity is present on the surface of active material particles or inside the same
Implementation Method 2
stabilization of crystal structure caused by variation in oxidation number by Li (lithium) present in the transition metal layer
Data Source
Figure 1
AI summary
Disclosed is a cathode for secondary batteries comprising a compound having a transition metal layer containing lithium as at least one compound selected from the following formula 1: (1-x)Li(LiyM1-y-zMaz)O2-bAb*xLi3PO4 (1) wherein M is an element stable for a six-coordination structure, which is at least one selected from transition metals that belong to first and second period elements; Ma is a metal or non-metal element stable for a six-coordination structure; A is at least one selected from the group consisting of halogen, sulfur, chalcogenide compounds and nitrogen; 0<x<0.1; 0<y<0.3; 0 ≤ z<0.2; and 0 ≤ b<0.1.