Positive Electrode Segmentation for Lithium Battery Capacity
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Solution Overview
Problem
There is a need to improve the high-rate characteristics and capacities of positive electrode active materials in lithium batteries to meet the demands of advanced mobile electronic devices, as existing lithium batteries face limitations in capacity and electrical performance.
Innovation Solution
A positive electrode is developed using a combination of a first lithium compound with an open-circuit voltage less than 3 V and a second lithium compound with an open-circuit voltage of 3 V or greater, along with a metal oxide coating layer, to enhance chemical stability and prevent deterioration during charging and discharging, thereby improving electrical characteristics and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a positive electrode active material is used to increase capacity, then the battery capacity increases, but the high-rate characteristics and electrical performance deteriorate
Solution Approach 1:
The positive electrode active material is segmented into two distinct compounds: a first lithium compound with open-circuit voltage less than 3 V and a second lithium compound with open-circuit voltage of 3 V or greater. This segmentation allows each compound to contribute differently to the overall battery performance, with the first compound providing high capacity and the second compound maintaining electrical characteristics and preventing over-discharge.
2Reliability
If the open-circuit voltage is increased to improve electrical characteristics, then the electrical performance improves, but the capacity retention rate deteriorates
Solution Approach 1:
The voltage range is segmented into two zones: a first lithium compound operating below 3 V and a second lithium compound operating at 3 V or higher. This segmentation enables the battery to achieve good electrical characteristics through the second compound while maintaining high capacity retention through the first compound, resolving the trade-off between electrical performance and capacity retention.
3Device complexity
If a single lithium compound is used to simplify the electrode structure, then the device complexity decreases, but the cycle performance and stability deteriorate
Solution Approach 1:
The positive electrode uses a composite structure combining two different lithium compounds with distinct open-circuit voltages. The first lithium compound (e.g., Li2MoO3 or LiFeO2) provides structural stability and high capacity retention, while the second lithium compound (e.g., LiCoO2 or LiNiO2) provides excellent electrical characteristics and prevents over-discharge. This composite material approach enhances overall cycle performance and stability.
Data Source
AI summary
A positive electrode having a surface on which a positive electrode active material composition including a positive electrode active material is formed. The positive electrode includes a first lithium compound having an open-circuit voltage less than 3V with respect to lithium metal, and a second lithium compound having an open-circuit voltage of 3 V or greater with respect to lithium metal. The first lithium compound includes a solid solution represented by Formula 1:xLizM1-yM′yO2-(1−x)LiaM″bMocO3.