Lithium Composite Oxide Cathode Material for High-Temperature Stability
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Solution Overview
Problem
Conventional lithium secondary battery positive electrode active materials face challenges with high-temperature storage stability and lifespan characteristics due to structural instability and issues with cation mixing, leading to reduced capacity and increased swelling.
Innovation Solution
A positive electrode active material comprising lithium composite oxide with primary and secondary particles and a lithium alloy oxide at the interface and surface, which enhances structural stability through concentration gradients, preventing structural collapse and improving lithium ion migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiCoO2 is used as positive electrode active material, then charge/discharge efficiency and lifespan characteristics are improved, but cost increases due to cobalt resource limitations
Solution Approach 1:
The patent modifies the chemical composition parameters of the positive electrode active material by incorporating multiple transition metals (Ni, Co, Mn, Al) in specific ratios. The formula Li1+xNi0.8-y-z-Co0.1-y-Al0.05-yMn0.05MO4-z represents a systematic parameter change approach where x, y, z control the stoichiometry to achieve both low cost and high reliability, reducing cobalt content while maintaining structural stability and charge/discharge efficiency
Solution Approach 2:
The patent creates a composite material system combining multiple transition metals (Ni, Co, Mn, Al, and additional metal M) in a spinel structure. This composite approach leverages the advantages of each metal: Ni for high capacity, Co for stability, Mn for cost-effectiveness and thermal safety, Al for structural reinforcement, and M for additional performance enhancement, achieving both cost reduction and reliability improvement simultaneously
2Quantity of substance
If LiMnO2 or LiMn2O4 is used as positive electrode active material, then cost decreases and thermal safety improves, but capacity and high-temperature characteristics deteriorate
Solution Approach 1:
The patent optimizes the manganese content and oxidation state by adjusting the formula parameters (Li1+xNi0.8-y-z-Co0.1-y-Al0.05-yMn0.05MO4-z), controlling the Mn3+/Mn4+ ratio to prevent Jahn-Teller distortion at high temperatures. The additional metal M and its concentration z are specifically tuned to enhance high-temperature structural stability while maintaining the cost advantage of manganese-based materials
Solution Approach 2:
The patent creates a composite spinel structure incorporating Mn with Ni, Co, Al, and M metals. This composite material approach combines the low cost and thermal safety of Mn-based materials with the high capacity of Ni, the stability of Co, the structural reinforcement of Al, and the high-temperature performance enhancement of M, simultaneously achieving cost reduction and improved high-temperature characteristics
3Quantity of substance
If LiNiO2-based positive electrode active material is used, then discharge capacity increases, but cation mixing between Li and transition metal occurs making synthesis difficult and rate characteristic deteriorates
Solution Approach 1:
The patent carefully controls the stoichiometric parameters to prevent cation mixing. The formula Li1+xNi0.8-y-z-Co0.1-y-Al0.05-yMn0.05MO4-z uses specific ranges for x, y, z to maintain Li layer integrity while achieving high Ni content for high capacity. The presence of Co, Al, and M at specific concentrations creates a synthesis pathway that avoids the cation mixing problems of pure LiNiO2, making the material manufacturable while retaining high discharge capacity
Solution Approach 2:
The patent creates a composite spinel structure where Ni is combined with Co, Al, Mn, and M metals. This composite approach mitigates the cation mixing issue of pure LiNiO2 by introducing elements with different ionic radii and charges (Co3+, Al3+, Mn4+, M) that stabilize the Li layers and prevent Ni migration into Li sites. The synergistic combination maintains high discharge capacity from Ni while improving ease of manufacture through more stable synthesis conditions
4Quantity of substance
If cation mixing intensifies in LiNiO2-based material, then Li by-products (LiOH and Li2CO3) increase causing gelation in paste preparation and gas generation during charge/discharge, but this is an unintended harmful effect
Solution Approach 1:
The patent controls the chemical composition parameters (x, y, z in Li1+xNi0.8-y-z-Co0.1-y-Al0.05-yMn0.05MO4-z) to minimize residual Li that would form LiOH and Li2CO3 by-products. By optimizing the stoichiometry and ensuring complete reaction, the patent reduces the formation of harmful by-products that cause gelation during paste preparation and gas generation during battery operation, transforming the process from one that generates harmful excess Li to one that achieves complete utilization
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 high-temperature storage stability and lifespan characteristics of lithium secondary batteries by maintaining structural integrity and enhancing lithium ion efficiency.
Implementation Method 1
A positive electrode active material comprising lithium composite oxide with primary and secondary particles and a lithium alloy oxide at the interface and surface, which enhances structural stability through concentration gradients, preventing structural collapse and improving lithium ion migration
Data Source
AI summary
The present invention relates to a positive electrode active material and a lithium secondary battery comprising the same.