Negative Electrode Tungsten Molybdenum Compounds Large-Current Output
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Solution Overview
Problem
Existing nonaqueous electrolyte secondary batteries do not adequately enhance output characteristics during large-current charging and discharging, despite previous techniques using graphite and carbon-based materials.
Innovation Solution
Incorporating a tungsten compound and/or a molybdenum compound into the negative electrode active material, which facilitates the formation of a quality film with improved lithium ion diffusibility, reducing resistance and enhancing output characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If graphite particles and carbonaceous particles are used as negative electrode active material, then capacity is improved, but output characteristics during large-current charging and discharging remain insufficient
Solution Approach 1:
The patent uses a composite material consisting of graphite particles coated with a pitch-carbon black mixture, combined with carbonaceous particles obtained by calcining the pitch-carbon black mixture. This composite structure provides both high capacity from the graphite and improved output characteristics from the carbon black components, resolving the contradiction between capacity and power.
Solution Approach 2:
The patent applies local quality by coating only the surface of graphite particles with a pitch-carbon black mixture rather than using bulk composite materials. This surface coating approach enhances output characteristics at the electrode surface while maintaining the high capacity of the graphite core, addressing the power-ccapacity trade-off.
2Quantity of substance
If a carbon material is used as negative electrode active material, then capacity is maintained, but lithium ion diffusibility on the surface is insufficient for large-current operation
Solution Approach 1:
The patent changes the surface parameters of the carbon material by coating with pitch-carbon black mixture and subjecting to calcination. This modifies the surface properties to enhance lithium ion diffusibility while preserving the bulk capacity of the graphite particles, enabling better large-current performance.
Solution Approach 2:
The pitch-carbon black mixture acts as an intermediary layer on the graphite particle surface. This intermediate coating facilitates lithium ion transport between the electrolyte and the graphite core, improving surface diffusibility without compromising the underlying capacity-storing graphite structure.
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 use of tungsten and molybdenum compounds enhances lithium ion mobility and prevents excessive coverage by poor diffusibility films, resulting in improved output characteristics during large-current charging and discharging.
Implementation Method 1
the incorporation of a tungsten compound and/or a molybdenum compound to the negative electrode results in the formation of a quality film having excellent lithium ion diffusibility on the surface of the negative electrode active material
Implementation Method 2
enhancement in the diffusibility of lithium ions on the surface of the negative electrode active material
Data Source
AI summary
The invention provides nonaqueous electrolyte secondary batteries having excellent output characteristics during large-current charging and discharging. A nonaqueous electrolyte secondary battery according to one aspect of the invention includes a positive electrode including a lithium transition metal oxide, a negative electrode including a negative electrode active material capable of storing and releasing lithium ions, and a nonaqueous electrolyte, the negative electrode active material including a carbon material as a main component, the negative electrode including a tungsten compound and/or a molybdenum compound. The tungsten compound and/or the molybdenum compound is preferably attached to the surface of the carbon material.