Nickel-Based Cathode Particle Structure for Crack-Resistant Li-Ion Cells
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Solution Overview
Problem
Lithium secondary batteries using lithium nickel manganese cobalt composite oxide or lithium cobalt oxide suffer from reduced lifespan due to crack formation in active material particles during charge/discharge cycles, leading to increased battery resistance and unsatisfactory capacity characteristics.
Innovation Solution
A nickel-based active material with a secondary particle structure featuring a radially arranged outer portion and an irregularly porous inner portion, prepared through a method involving heat treatments in oxidative gas atmospheres, is used to reduce crack formation and enhance lithium diffusion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If conventional lithium nickel manganese cobalt composite oxide or lithium cobalt oxide is used as positive active material, then battery capacity can be achieved, but crack formation occurs in active material particles during charge/discharge cycles reducing lifespan
Solution Approach 1:
The patent introduces a porous coating layer on the surface of the active material particles. This porous structure allows for buffer space during lithium insertion/extraction cycles, accommodating volume changes and preventing crack formation in the particles, thereby improving battery lifespan and reliability
Solution Approach 2:
The patent creates a composite structure by coating the active material particles with a porous material layer. This composite approach combines the high capacity benefits of lithium nickel manganese cobalt composite oxide or lithium cobalt oxide with the protective and buffer properties of the porous coating, resolving the contradiction between capacity and lifespan
2Use of energy by moving object
If positive active material is used for high capacity, then energy density improves, but battery resistance increases due to particle cracking
Solution Approach 1:
The porous coating layer maintains low battery resistance by providing continuous ion transport pathways while protecting the active material particles from cracking. The porous structure allows efficient lithium ion diffusion without the resistance increase caused by particle degradation, thus maintaining both high energy density and low resistance
3Duration of action of moving object
If charge/discharge cycles are repeated to achieve operational duration, then battery usage time increases, but crack formation reduces capacity characteristics
Solution Approach 1:
The porous coating layer prevents crack formation during repeated charge/discharge cycles, maintaining the structural integrity of active material particles. This preservation of particle structure ensures that battery capacity characteristics remain satisfactory throughout the operational duration, allowing repeated cycling without significant capacity loss
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 nickel-based active material improves the lifespan and reduces resistance of lithium secondary batteries by minimizing crack formation and optimizing lithium diffusion, resulting in enhanced cell performance and capacity retention.
Implementation Method 1
performing a first heat treatment on a mixture of a lithium precursor and a metal hydroxide at a temperature of about 600° C. to about 800° C. in an oxidative gas atmosphere
Implementation Method 2
performing a first heat treatment on a mixture of a lithium precursor and a metal hydroxide at a temperature of about 600° C. to about 800° C. in an oxidative gas atmosphere
Data Source
AI summary
A nickel-based active material for a lithium secondary battery, a method of preparing the nickel-based active material, and a lithium secondary battery including a positive electrode including the nickel-based active material, the nickel-based active material comprising a secondary particle having an outer portion with a radially arranged structure and an inner portion with an irregular porous structure, wherein the inner portion of the secondary particle has a larger pore size than the outer portion of the secondary particle.