Cathode Material Pore Structure for Capacity Retention in Li-Ion Batteries
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Solution Overview
Problem
Lithium-ion batteries face challenges in balancing short-term and long-term properties during charging and discharging due to inappropriate pore distribution in cathode materials, leading to surface structure collapse and reduced capacity retention.
Innovation Solution
A cathode material with specific pore diameter distribution and microcrystallite structure is developed, achieved through a method involving the co-precipitation of nickel, cobalt, and M salts with controlled pH phases, followed by sintering and heat treatment, to optimize pore distribution and crystal structure for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the pore diameter is larger and more pores are presented, then the initial capacity is improved, but the surface crystal structure collapses during charging and discharging, reducing capacity retention
Solution Approach 1:
The patent applies local quality by creating different porosity characteristics in different regions of the cathode material particles. The surface region has controlled porosity to facilitate electrolyte penetration and lithium ion diffusion, while the interior maintains structural integrity. This is achieved through specific preparation methods that create a gradient or differentiated pore structure, allowing the surface to provide high initial capacity while the interior supports long-term structural stability during cycling.
Solution Approach 2:
The patent utilizes porous materials by intentionally creating a controlled pore structure within the cathode material particles. The porosity is optimized to balance two competing requirements: sufficient pore diameter and connectivity for electrolyte access and lithium ion transport (improving initial capacity), and appropriate pore size distribution to prevent surface crystal structure collapse (maintaining capacity retention). The pore structure is engineered through preparation parameters such as sintering conditions, particle morphology control, and surface treatment.
2Productivity
If the pore diameter is larger and more pores are presented, then the electrolyte immersion and lithium ion deintercalation are enhanced, but the surface crystal structure collapses, decreasing service life
Solution Approach 1:
The patent applies parameter changes by optimizing the pore diameter within a specific range and controlling the porosity distribution to achieve the desired balance. By carefully adjusting the pore diameter parameter (not too small to block ion transport, not too large to cause structural collapse) and controlling other preparation parameters (temperature, time, atmosphere during sintering), the patent creates a pore structure that enables efficient lithium ion deintercalation while maintaining surface crystal structure stability for extended service life.
3Quantity of substance
If the exterior porosity is increased to increase initial capacity, then the surface may easily collapse during charging and discharging, causing dead lithium and capacity decrease
Solution Approach 1:
The patent applies local quality by creating different porosity characteristics in different regions of the cathode material particles. The surface region has controlled porosity to facilitate electrolyte penetration and lithium ion diffusion, while the interior maintains structural integrity. This is achieved through specific preparation methods that create a gradient or differentiated pore structure, allowing the surface to provide high initial capacity while the interior supports long-term structural stability during cycling.
Solution Approach 2:
The patent applies beforehand cushioning by pre-establishing a robust pore structure during material synthesis that can withstand the mechanical and chemical stresses of subsequent charging and discharging cycles. The pore structure is designed with appropriate wall thickness and structural support features that prevent collapse before it occurs during battery operation, thereby preventing dead lithium formation and 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 cathode material enhances both initial charge-discharge capacity and long-term capacity retention by regulating surface impedance and preventing surface crystal structure collapse, thereby extending battery life.
Implementation Method 1
provide sufficient interfaces for the immersion of the electrolyte and the deintercalation of lithium ions during the charging and discharging process
Implementation Method 2
provide sufficient interfaces for the immersion of the electrolyte
Implementation Method 3
a method involving the co-precipitation of nickel, cobalt, and M salts with controlled pH phases
Implementation Method 4
followed by sintering and heat treatment, to optimize pore distribution and crystal structure
Implementation Method 5
followed by sintering and heat treatment, to optimize pore distribution and crystal structure
Data Source
AI summary
The present invention relates to the field of lithium ion battery positive electrode materials, and discloses a positive electrode material, a preparation method therefor, a use thereof, and a lithium ion battery.