Cathode Active Material Gradient Structure to Limit Particle Strain
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Solution Overview
Problem
Lithium secondary batteries face challenges with limited energy density, lifetime, and stability due to issues with existing positive electrode active materials like LiCoO2, LiMnO2, and LiNiO2, which suffer from high costs, thermal safety concerns, and difficulties in synthesis, leading to reduced cycle life and swelling.
Innovation Solution
A positive electrode active material with primary particles exhibiting an aspect ratio gradient increasing from the core to the surface of secondary particles, optimized by doping with metal elements like niobium and adjusting calcination conditions, to improve lithium intercalation/deintercalation efficiency and reduce strain during charging/discharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiCoO2 is used as positive electrode active material, then charge/discharge efficiency and lifetime characteristics are improved, but cost increases due to limited cobalt resource
Solution Approach 1:
The patent changes the chemical composition parameters by replacing cobalt with nickel and manganese in specific ratios (LiNi1-x-yMnxO2 where 0.5<x<0.95 and 0.05<y<0.5), thereby reducing material cost while maintaining electrochemical performance through optimized stoichiometry
Solution Approach 2:
The patent creates a composite positive electrode active material combining nickel-rich lithium composite oxide with specific crystal structures, integrating the advantages of high capacity (from nickel) and stability (from controlled manganese content and crystal structure) to achieve both performance and cost-effectiveness
2Ease of manufacture
If LiMnO2 or LiMn2O4 is used as positive electrode active material, then thermal safety and cost are improved, but capacity and high-temperature characteristics deteriorate
Solution Approach 1:
The patent optimizes the manganese content parameter (y) to a specific range (0.05<y<0.5) in the LiNi1-x-yMnxO2 composition, balancing the thermal stability contribution from manganese with the capacity contribution from nickel, thereby achieving both safety and high capacity
3Quantity of substance
If LiNiO2-based positive electrode active material is synthesized, then discharge capacity is improved, but synthesis difficulty increases due to cation mixing between Li and transition metal
Solution Approach 1:
The patent adjusts the nickel content parameter (x) to a specific range (0.5<x<0.95) and combines it with optimized manganese content and crystal structure control, enabling high-capacity performance while reducing cation mixing through compositional optimization that facilitates easier synthesis
Solution Approach 2:
The patent develops a composite material system where nickel-rich lithium composite oxide is combined with specific crystal structures, creating a material that achieves high discharge capacity while maintaining synthesis feasibility through structured composite design that mitigates cation mixing issues
4Ease of manufacture
If cation mixing between Li and transition metal is intensified, then synthesis becomes easier, but Li by-products increase causing gelation and gas generation
Solution Approach 1:
The patent optimizes the compositional parameters (x and y values) to achieve a balance where moderate cation mixing occurs during synthesis, facilitating material formation while the specific composition range limits excessive by-product generation that would cause gelation and gas evolution
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 enhances energy density, lifetime, and stability of lithium secondary batteries by minimizing strain and improving electrochemical characteristics, such as charge capacity and efficiency, while maintaining a spherical shape gradient to prevent cracking and side reactions.
Implementation Method 1
a lithium secondary battery storing electrical energy due to a difference in chemical potential when lithium ions are intercalated/deintercalated into/from a positive electrode and a negative electrode
Implementation Method 2
primary particles exhibiting an aspect ratio gradient increasing from the core to the surface of secondary particles, optimized by doping with metal elements like niobium and adjusting calcination conditions, to improve lithium intercalation/deintercalation efficiency and reduce strain during charging/discharging
Implementation Method 3
optimized by doping with metal elements like niobium and adjusting calcination conditions, to improve lithium intercalation/deintercalation efficiency and reduce strain during charging/discharging
Implementation Method 4
optimized by doping with metal elements like niobium and adjusting calcination conditions
Data Source
AI summary
The present invention relates to a positive electrode active material having improved electrical characteristics by adjusting an aspect ratio gradient of primary particles included in a secondary particle, a positive electrode including the positive electrode active material, and a lithium secondary battery using the positive electrode.