Nickel Cathode Core-Shell Cladding for Faster Lithium-Ion Diffusion

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Solution Overview

Problem

Nickel-based electrode active materials for lithium ion batteries have a low lithium ion diffusion coefficient, leading to low charging and discharging efficiency and poor electrochemical performance due to limited lithium ion migration performance.

Innovation Solution

A positive electrode material with a core-shell structure, where a rock-salt phase cladding layer is applied to the surface of secondary particles formed by stacking primary particles, enhancing lithium ion migration and structural stability by enriching diffusion paths and improving electrolyte retention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If nickel-based electrode active materials are used, then high specific capacity and high energy density are achieved, but lithium ion diffusion coefficient is low leading to poor charging and discharging efficiency

Engineering Contradiction:

Improveenergy densityVSAvoidlithium ion diffusion coefficient

Core Design Contradiction:

Use of energy by moving objectVSSpeed

Solution Approach 1:

The electrode material is divided into hierarchical structures with primary particles aggregated into secondary particles, creating multiple diffusion pathways that shorten the distance lithium ions must travel, thereby improving diffusion coefficient while maintaining high capacity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the electrode material are designed with different properties - the hierarchical structure provides optimized local diffusion paths, while the overall composition maintains high nickel content for energy density

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If particle size is increased to improve capacity, then energy density improves, but lithium ion migration performance deteriorates

Engineering Contradiction:

ImprovecapacityVSAvoidlithium ion migration rate

Core Design Contradiction:

Quantity of substanceVSSpeed

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The diffusion path is extended from one-dimensional radial diffusion in spherical particles to three-dimensional hierarchical networks, allowing lithium ions to migrate through multiple pathways simultaneously, effectively increasing migration rate without reducing capacity

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 solution significantly improves lithium ion migration rate and electrochemical performance, leading to enhanced charge and discharge rates and capacity retention, suitable for high-energy density secondary batteries.

Implementation Method 1

enriching diffusion paths and improving electrolyte retention

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS20250023043A1Positive electrode material and application thereof

Publication Date: 2025.01.16 BYD CO LTD

AI summary

A positive electrode material and an application thereof are provided. The positive electrode material comprises a secondary particle formed by stacking a plurality of primary particles. The positive electrode material further comprises a rock-salt phase cladding layer disposed on a surface of the secondary particle. A ratio of a particle size of the secondary particle to an average particle size of the primary particles is greater than or equal to 1.5; and the primary particles and the rock-salt phase cladding layer respectively comprise a nickel-based active material.