Fluorine-Boron Coated Cathode Material for Stable High-Rate Batteries
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Solution Overview
Problem
Existing overlithiated lithium manganese-based oxides suffer from low electrochemical properties and stability due to excessive manganese, leading to elution of transition metals and impurity formation, which reduces charge/discharge capacity and rate performance in lithium secondary batteries.
Innovation Solution
A positive electrode active material is developed by forming a coating layer containing fluorine and boron on the surface of lithium manganese-based oxide, which suppresses the elution of transition metals and enhances the electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If an overlithiated lithium manganese-based oxide is used as a positive electrode active material, then high capacity can be theoretically exhibited under high voltage operating environment, but electrical conductivity is relatively low due to excessive amount of Mn, resulting in poor rate performance
Solution Approach 1:
A coating layer containing fluorine and boron is introduced as an intermediary between the lithium manganese-based oxide and the electrolyte. This coating layer mediates the interaction by suppressing direct contact and harmful reactions while maintaining ionic conductivity, thereby improving rate performance without sacrificing capacity.
Solution Approach 2:
The positive electrode active material is transformed into a composite structure by combining lithium manganese-based oxide with a fluorine-boron containing coating layer. This composite material approach allows the core oxide to provide high capacity while the coating provides enhanced electrical conductivity and stability.
2Quantity of substance
If an overlithiated lithium manganese-based oxide with excessive Mn is used, then high capacity is achievable, but transition metals elute and impurities form, reducing charge/discharge capacity and rate performance
Solution Approach 1:
The fluorine-boron coating layer is applied in advance to prevent the elution of transition metals and formation of impurities. By establishing this protective barrier before electrochemical reactions occur, the coating preemptively counteracts the harmful effects of Mn elution and impurity formation during battery cycling.
Solution Approach 2:
The coating layer acts as an intermediary that blocks the direct interaction between the lithium manganese-based oxide and the electrolyte, preventing transition metal elution and impurity formation while still allowing lithium ion transport.
3Ease of manufacture
If Li by-products are generated due to cation mixing, then the positive electrode paste may gelate or gas may be generated during charging/discharging, but this degrades lifetime characteristics
Solution Approach 1:
The fluorine-boron coating is applied preliminarily to prevent cation mixing and suppress the generation of Li by-products such as LiOH and Li2CO3. By preventing these by-products from forming in the first place, the coating avoids gelation during electrode preparation and gas generation during cycling, thereby extending battery lifetime.
4Reliability
If a coating layer is formed to suppress transition metal elution, then electrochemical stability is improved, but manufacturing complexity increases
Solution Approach 1:
The coating formation process is merged with the existing electrode manufacturing process by incorporating fluorine and boron compounds into the slurry preparation stage. This integration allows the coating to be applied during normal manufacturing operations without requiring separate coating equipment or additional processing steps, thereby limiting the increase in manufacturing complexity.
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 proposed solution improves the discharge capacity, charge/discharge efficiency, and rate performance of lithium secondary batteries by reducing side reactions and maintaining high stability under high voltage conditions.
Implementation Method 1
forming a coating layer containing fluorine and boron on the surface of lithium manganese-based oxide, which suppresses the elution of transition metals
Implementation Method 2
A positive electrode active material is developed by forming a coating layer containing fluorine and boron on the surface of lithium manganese-based oxide
Implementation Method 3
when lithium ions are intercalated/deintercalated into/from a positive electrode and a negative electrode
Implementation Method 4
Batteries store electrical power by using materials facilitating an electrochemical reaction at a positive electrode and a negative electrode
Data Source
AI summary
The present invention relates to a positive electrode active material and a lithium secondary battery including the same, and more particularly, to a positive electrode active material including an overlithiated lithium manganese-based oxide, which can improve the electrochemical properties of a lithium secondary battery including discharge capacity and rate performance, which are reduced by lithium and manganese present in excess in the lithium manganese-based oxide, and a lithium secondary battery including the same.