Dual-Layer Coated Lithium Ion Active Material for Low Internal Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium ion secondary cells face challenges in reducing internal resistance, which limits their performance and efficiency in charge and discharge cycles.
Innovation Solution
A lithium ion secondary cell configuration with a positive electrode active material coated with two layers: a metal oxide layer and an ion conductive layer, where the electronegativity difference between the central elements of the metal oxide and lithium ion conductor promotes the formation of lithium-rich and lithium-deficient regions, facilitating low-resistance lithium ion insertion and removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the surface of active material particles is coated with a lithium ion conductive material, then lithium ions can be smoothly inserted in and removed from all directions, but the internal resistance of the cell cannot be sufficiently reduced
Solution Approach 1:
The patent applies local quality by creating a dual-layer coating structure where the metal oxide layer and lithium ion conductive layer are positioned at different locations on the active material particle surface. The metal oxide layer is placed at regions where lithium ion insertion/removal occurs, while the lithium ion conductive layer covers other surface areas. This spatial differentiation of coating materials optimizes both lithium ion transport smoothness and internal resistance reduction by assigning specific functional zones on the particle surface.
2Reliability
If a single lithium ion conductive coating layer is used, then lithium ion conductivity is improved, but the formation of lithium-rich and lithium-deficient portions is insufficient for optimal performance
Solution Approach 1:
The patent segments the coating structure into two distinct layers: a metal oxide layer and a lithium ion conductive layer. This segmentation allows each layer to perform its specific function - the metal oxide layer facilitates lithium ion insertion and removal by creating lithium-rich and lithium-deficient portions, while the lithium ion conductive layer ensures smooth lithium ion transport across the particle surface. The segmented structure resolves the contradiction by separating the functions of ion conductivity and lithium ion concentration gradient formation.
Solution Approach 2:
The patent employs composite materials by combining metal oxide and lithium ion conductive material in a dual-layer coating system. This composite structure leverages the complementary properties of both materials - the metal oxide's ability to form lithium concentration gradients and the lithium ion conductive material's high ionic conductivity - to simultaneously achieve optimal charge/discharge rates and lithium ion conductivity without sacrificing either performance metric.
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
This configuration significantly reduces the internal resistance of the cell, enhancing its capacity retention ratio and enabling high-rate charging and discharging with maintained energy density.
Implementation Method 1
where an electronegativity of a central element of the metal oxide is denoted by χM and an electronegativity of a central element of the lithium ion conductor is denoted by χM′, these satisfy χM>χM′
Data Source
AI summary
The art disclosed herein provides a lithium ion secondary cell in which the internal resistance of the secondary cell is further reduced. A lithium ion secondary cell includes electrodes including an active material. The active material includes, on the surface, two coating layers of a metal oxide layer including a metal oxide and an ion conductive layer including a lithium ion conductor. The metal oxide layer and the ion conductive layer are adjacent to each other.