Composite Cathode and High-Capacity Anode for EV Battery Energy Density
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Solution Overview
Problem
Conventional lithium secondary batteries with layered lithium cobalt composite oxide cathodes are expensive and prone to safety issues due to volume changes during Li ion intercalation/deintercalation, while batteries with spinel lithium manganese composite oxide cathodes lack sufficient energy density for electric vehicles, and amorphous carbon anodes have low energy density.
Innovation Solution
A high-energy lithium secondary battery is developed with a cathode comprising a mixture of layered lithium transition metal oxides and spinel lithium manganese oxides, combined with amorphous carbon anodes having a capacity of 300 mAh/g or more, and a separator with specific physical properties to enhance energy density and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium cobalt composite oxide with layered structure is used as cathode active material, then discharge voltage and energy density are improved, but safety deteriorates due to volume changes and structural collapse during Li ion intercalation/deintercalation
Solution Approach 1:
The patent uses a composite cathode material consisting of lithium cobalt oxide (layered structure) and lithium manganese oxide (spinel structure). The layered structure provides high discharge voltage and energy density, while the spinel structure provides structural stability during Li ion intercalation/deintercalation, preventing collapse and improving safety. This composite approach allows both materials to complement each other's advantages.
2Reliability
If lithium manganese composite oxide with spinel structure is used as cathode active material, then safety and structural stability are improved, but energy density deteriorates making it unsuitable for EV applications
Solution Approach 1:
The patent combines lithium manganese oxide (spinel structure) with lithium cobalt oxide (layered structure) in a composite cathode material. The spinel structure contributes structural stability and safety, while the layered structure contributes high discharge voltage and energy density. By merging these two materials, the composite achieves both structural stability and high energy density suitable for EV applications.
3Power
If amorphous carbon is used as anode active material, then output characteristics are improved, but energy density deteriorates to less than 300 mAh/g
Solution Approach 1:
The patent changes the key parameter of amorphous carbon by controlling its specific surface area to be within a specific range (0.0035 to 0.0170 m²/mAh). This parameter optimization allows the amorphous carbon to achieve both good output characteristics and high energy density (300 mAh/g or more), resolving the contradiction between output performance and energy storage capacity.
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 battery achieves high energy density and output characteristics suitable for electric vehicles, with improved lifespan and safety, outperforming conventional amorphous carbon batteries in energy storage capacity and stability.
Implementation Method 1
the layered structure thereof undergoes changes in volume according to repeated intercalation and deintercalation of Li ions
Implementation Method 2
an anode including amorphous carbon having a capacity of 300 mAh/g or more
Data Source
AI summary
Disclosed is a high-energy lithium secondary battery including: a cathode including, as cathode active materials, a first cathode active material represented by Formula 1 below and having a layered structure and a second cathode active material represented by Formula 2 below and having a spinel structure, wherein the amount of the first cathode active material is between 40 and 100 wt % based on a total weight of the cathode active materials; an anode including amorphous carbon having a capacity of 300 mAh/g or more; and a separator.