Phosphorus-Carbon Composite Anode Material for Capacity and Cycle Life
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Solution Overview
Problem
Existing lithium secondary batteries require a negative electrode active material with improved durability and performance, including enhanced charge and discharge capacities, which is not adequately met by current materials.
Innovation Solution
A phosphorus-carbon composite material with a specific content ratio of phosphorus and carbon, characterized by a unique thermogravimetric profile and the presence of a P-C bond, is developed. This composite material is produced through a method involving mixing and grinding processes accompanied by compression, resulting in a core-shell structure with a carbon film covering a phosphorus core particle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If phosphorus is added to carbon material to improve charge and discharge capacities, then battery performance is improved, but durability deteriorates
Solution Approach 1:
The patent creates a phosphorus-carbon composite material where phosphorus atoms are incorporated into the carbon matrix at controlled ratios (10-95 mass% P, 5-90 mass% C). This composite structure combines the high capacity of phosphorus with the stability of carbon, resolving the contradiction between improved power and maintained reliability
Solution Approach 2:
The patent optimizes the phosphorus content ratio parameter to specifically 10-95 mass% and carbon content to 5-90 mass%, with the additional constraint that WL620/WL780 ratio falls between 0.1-0.9. These parameter changes transform the material properties to achieve both high capacity and durability simultaneously
2Power
If phosphorus content is increased to enhance battery performance, then charge and discharge capacities improve, but material stability worsens
Solution Approach 1:
By forming a phosphorus-carbon composite rather than using pure phosphorus, the patent maintains material stability while achieving high capacity. The carbon matrix provides structural stability even when phosphorus content is high (up to 95 mass%), preventing phosphorus from undergoing detrimental phase transformations
Solution Approach 2:
The patent establishes specific parameter ranges for phosphorus content (10-95 mass%) and carbon content (5-90 mass%), along with the thermogravimetric parameter WL620/WL780 (0.1-0.9). These parameter constraints ensure the material maintains stability while achieving desired performance
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 phosphorus-carbon composite material significantly enhances the performance of lithium secondary batteries by improving charge and discharge capacities and maintaining excellent cycle characteristics, thus addressing the need for a more durable and high-performance negative electrode active material.
Implementation Method 1
a ratio WL620/WL780 of a weight loss ratio WL620 at a measurement temperature of 620° C. and a weight loss ratio WL780 at a measurement temperature of 780° C., which are obtained by thermogravimetric measurement under the following conditions
Data Source
AI summary
A phosphorus-carbon composite material includes: phosphorus atoms; and carbon atoms, in which a content ratio of the phosphorus atoms in the phosphorus-carbon composite material is 10 mass % or more and 95 mass % or less, a content ratio of the carbon atoms in the phosphorus-carbon composite material is 5 mass % or more and 90 mass % or less, and a ratio WL620/WL780 of a weight loss ratio WL620 at a measurement temperature of 620° C. and a weight loss ratio WL780 at a measurement temperature of 780° C., which are obtained by thermogravimetric measurement under the following conditions, is 0.1 or more and 0.9 or less. (Thermogravimetric measurement) 10 mg of the phosphorus-carbon composite material is accurately weighed to prepare a sample, and using a thermogravimetric measuring device, a weight change when the sample is heated from 50° C. to 780° C. at a temperature rising rate of 10° C./min in N2 is measured. (Weight loss ratio) A ratio of a weight of the sample at the measurement temperature to a weight of the accurately weighed sample is defined as a weight loss ratio (weight %) at the measurement temperature.