Carbon-Coated Cathode Particles With Controlled Cracking for Cycle Life
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Solution Overview
Problem
Traditional secondary batteries face challenges in achieving both high capacity and long-cycle performance, limiting their application in energy storage due to issues with compaction density, conductivity, and structural stability.
Innovation Solution
The secondary battery design includes cathode active particles with controlled cracking, featuring cracks of 10-30 nm width and 300-800 nm length, which enhances compaction density, specific surface area, and pore volume, exposing active sites for improved lithium ion intercalation and deintercalation, while maintaining structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If compaction treatment is applied to increase capacity, then discharge specific capacity is improved, but structural stability deteriorates causing poor cycle performance
Solution Approach 1:
The cathode active material particles are segmented into multiple size ranges (D10: 0.3-0.6 μm, D50: 0.6-1.2 μm, D90: 2-4 μm), creating a distributed particle size structure that balances compaction density and structural integrity, allowing improved capacity while maintaining cycle stability
Solution Approach 2:
Different regions of the particle size distribution are assigned different functions: small particles (D10) fill voids to increase compaction density and capacity, while larger particles (D90) maintain structural framework stability, creating local quality differentiation that resolves the capacity-stability contradiction
2Quantity of substance
If compaction density is increased to improve capacity, then energy density is improved, but conductivity deteriorates
Solution Approach 1:
The compaction density is optimized to a specific range (2.4-2.8 g/cm³) rather than maximized, and particle size parameters (D10, D50, D90) are adjusted to maintain appropriate inter-particle spacing that preserves conductivity pathways while achieving high enough compaction density for improved capacity
3Speed
If particle size is reduced to increase specific surface area, then lithium ion intercalation rate is improved, but structural stability deteriorates
Solution Approach 1:
The particle population is segmented into a broad size distribution rather than using uniform fine particles, allowing small particles to provide high surface area for fast lithium ion intercalation while larger particles maintain the structural framework
Solution Approach 2:
The cathode active material is combined with a carbon coating layer to form a composite structure that enhances both the rate capability (through improved conductivity and surface area) and structural stability (through the protective carbon shell) of the particles
4Quantity of substance
If capacity is increased through compaction, then energy density is improved, but cycle life deteriorates
Solution Approach 1:
The compaction density is changed to an optimized range (2.4-2.8 g/cm³) that achieves high capacity while avoiding excessive stress that would damage particle structure during cycling, and particle size parameters are adjusted to balance capacity and cycle stability
Solution Approach 2:
A carbon coating layer is applied to the cathode active material particles to form a composite structure that protects the particles from mechanical degradation during cycling, thereby extending cycle life while maintaining high capacity
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 approach improves discharge specific capacity and cycle performance, enabling batteries to achieve high capacity and long-cycle life, suitable for energy storage applications.
Implementation Method 1
subjecting the precursor to a staged compaction treatment to obtain cathode active particles
Implementation Method 2
The cathode active particles include a core and a carbon layer coating the core
Implementation Method 3
exposing active sites for improved lithium ion intercalation and deintercalation
Data Source
AI summary
The present disclosure relates to a secondary battery and a method for preparing the same, a battery pack, an energy storage system, and an electric apparatus. The secondary battery includes cathode active particles. The cathode active particles include a core and a carbon layer coating the core, and the core includes at least one of a lithium transition metal phosphate and a lithium transition metal oxide. Part of the cathode active particles are cracked, an average width of cracks is in a range of 10 nm to 30 nm, and an average length thereof is in a range of 300 nm to 800 nm.