Boron-Rich Carbon Negative Electrode for High Capacity Lithium Batteries
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Solution Overview
Problem
Lithium ion batteries face a challenge in increasing the cruising distance of electric cars due to the limited capacity of negative electrode active materials, particularly in the voltage range of 0 to 2 V, where existing materials like graphite do not efficiently occlude and release lithium ions, leading to suboptimal discharge capacity.
Innovation Solution
A negative electrode active material with a layer structure composed of carbon, boron, and nitrogen or phosphorus, where lithium is present in the interlayer portions, denoted by the composition formula LixByCzMq, with a molar ratio of boron to carbon exceeding 0.6, enhancing discharge capacity density and electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If graphite is used as negative electrode active material, then the battery structure is simple and easy to manufacture, but the discharge capacity density is limited and cannot efficiently occlude and release lithium ions in the voltage range of 0 to 2 V
Solution Approach 1:
The patent employs composite materials by combining carbon, boron, and nitrogen or phosphorus elements to form a layered structure with composition formula LixByCzMq. This composite approach enables the material to achieve high discharge capacity density while maintaining structural stability and electrical conductivity, resolving the contradiction between ease of manufacture and discharge capacity density.
Solution Approach 2:
The patent applies parameter changes by optimizing the molar ratio of boron to carbon to be more than 0.6, and controlling the presence of nitrogen or phosphorus in specific ratios. These parameter optimizations enable the material to achieve superior lithium ion occlusion and release performance in the 0 to 2 V range while maintaining manufacturability.
2Quantity of substance
If the boron content is increased to improve discharge capacity density, then the electrical conductivity may deteriorate, but the patent achieves both high capacity and conductivity through optimized composition
Solution Approach 1:
The patent resolves this contradiction by precisely controlling the compositional parameters: maintaining a boron to carbon molar ratio greater than 0.6 while incorporating nitrogen or phosphorus at controlled ratios. This parameter optimization ensures that high boron content for capacity enhancement does not compromise electrical conductivity, achieving both high discharge capacity density and reliable conductivity.
Solution Approach 2:
The layered composite structure comprising carbon, boron, and nitrogen or phosphorus creates a synergistic effect where the composite material simultaneously provides high discharge capacity density through boron-rich composition and maintains electrical conductivity through the layered structure and nitrogen/phosphorus doping.
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 negative electrode active material achieves a higher discharge capacity density and improved electrical conductivity, effectively increasing the battery's energy storage capacity and range, while maintaining a balance between capacity and conductivity.
Implementation Method 1
lithium is present in the interlayer portions
Implementation Method 2
improved electrical conductivity
Data Source
AI summary
A negative electrode active material includes a plurality of layers and lithium located between the plurality of layers, each of the plurality of layers containing carbon and boron, and nitrogen or phosphorus, wherein a molar ratio of the boron to the carbon is more than 0.6.