Overlithiated Lithium Transition Metal Oxide Fluorine Doping
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Solution Overview
Problem
Current positive active materials for lithium batteries, such as transition metal compounds, have limited electrical capacity and low rate properties due to low electrical and ion conductivities, making them unsuitable for high-capacity and high-rate applications, particularly in vehicles.
Innovation Solution
A method involving acid-treating overlithiated lithium transition metal oxides and applying fluorine doping using a fluorine compound to improve the rate properties, which includes specific formulations and processing conditions to enhance the composite positive active material's performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a composite oxide with layer structure (Li2MO3—LiMeO2) is used as positive active material, then the electrical capacity is improved due to large amount of lithium ion intercalation/deintercalation, but the rate property deteriorates due to low electrical and ion conductivities
Solution Approach 1:
The patent applies fluorine doping to change the chemical composition and electronic structure of the composite oxide, thereby improving electrical conductivity and ion diffusion rates. The fluorine substitution modifies the material's parameters at the atomic level, enabling high capacity while achieving improved rate properties through enhanced charge transport
Solution Approach 2:
The patent creates a composite structure by doping fluorine into the Li2MO3—LiMeO2 layer structure, forming a new composite material that combines the high capacity characteristics of the layered oxide with the high conductivity benefits of fluorine incorporation, thus resolving the contradiction between capacity and rate
2Reliability
If traditional transition metal compounds (LiNiO2, LiCoO2, LiFePO4) are used as positive active material, then the manufacturing process is simple and reliable, but the electrical capacity is limited
Solution Approach 1:
The patent develops a composite oxide system (Li2MO3—LiMeO2) that combines multiple transition metal oxides in a layered structure, enabling lithium ion intercalation/deintercalation in fundamentally large amounts compared to traditional single-phase materials, thus achieving high capacity while maintaining manufacturing feasibility
Solution Approach 2:
The patent modifies the stoichiometric composition and crystal structure parameters of the composite oxide to optimize lithium ion accessibility and capacity, achieving superior electrical capacity compared to conventional transition metal compounds while maintaining structural stability for reliable manufacturing
3Speed
If fluorine doping is applied to improve rate property, then the electrical and ion conductivities are improved, but the manufacturing process complexity increases
Solution Approach 1:
The patent incorporates fluorine doping during the initial synthesis process of the composite oxide, rather than as a separate post-treatment step. This preliminary action integrates the doping process into the main manufacturing flow, improving rate properties while minimizing additional process complexity
Solution Approach 2:
The patent optimizes the fluorine doping level and synthesis conditions to achieve the desired conductivity improvement with minimal process complexity, by carefully controlling compositional parameters and processing conditions during the composite oxide formation
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 method results in a composite positive active material with improved rate properties and high capacity, suitable for lithium batteries, particularly for vehicles, by extending the c-axis relevant to the rate property and maintaining electrochemical stability.
Implementation Method 1
applying a fluorine doping onto the acid-treated overlithiated lithium transition metal oxide using a fluorine compound
Implementation Method 2
acid-treating an overlithiated lithium transition metal oxide
Data Source
AI summary
Provided are a method of manufacturing a composite positive active material, a composite positive active material manufactured by the method, and a positive electrode and a lithium battery including the composite positive active material. The method may include acid-treating an overlithiated lithium transition metal oxide; and applying fluorine onto the acid-treated overlithiated lithium transition metal oxide using a fluorine compound.