Silicon Negative Electrode Conductive Additive Ratio
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Solution Overview
Problem
Lithium-ion secondary batteries using carbon as a negative active material face limitations in discharge capacity enhancement and cycle performance due to the pulverization of silicon-based materials during charge/discharge, leading to reduced capacity and short cycle life.
Innovation Solution
A non-aqueous electrolyte secondary battery design incorporating a negative active material composed of silicon-containing particles coated with electronic conductive additives and carbon, with a specific weight ratio of conductive additives between 0.5 wt.% to 60 wt.% to improve cycle life and discharge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon material is used as a negative active material to enhance discharge capacity, then the discharge capacity increases, but the cycle performance deteriorates due to pulverization
Solution Approach 1:
The patent uses a composite particle structure where silicon-containing particles are coated with carbon material and mixed with electronic conductive additives. This composite structure allows silicon to provide high discharge capacity while the carbon coating and conductive additives prevent pulverization and maintain structural integrity during charge/discharge cycles, thus improving cycle performance.
Solution Approach 2:
The patent applies different materials to different parts of the composite particle: silicon-containing particles are coated with carbon material on their surface, and electronic conductive additives are distributed within the particle structure. This local differentiation allows the silicon core to provide high capacity while the carbon coating and conductive additives locally prevent pulverization and maintain conductivity.
2Reliability
If silicon is coated with carbon material to improve cycle performance, then cycle performance improves, but contact conductivity between particles deteriorates
Solution Approach 1:
The patent applies carbon coating locally on the silicon particle surface to prevent pulverization, while simultaneously introducing electronic conductive additives in specific amounts (0.5-60 wt%) to restore and enhance contact conductivity between particles. This local quality differentiation resolves the contradiction between protection and conductivity.
Solution Approach 2:
The patent changes the parameter of electronic conductive additive content to an optimal range (0.5-60 wt%) to balance the protective effect of carbon coating with the need for adequate contact conductivity. By adjusting this parameter, the patent achieves both improved cycle performance and maintained conductivity.
3Manufacturing precision
If electronic conductive additive content is increased to improve contact conductivity, then contact conductivity improves, but discharge capacity per active material weight decreases
Solution Approach 1:
The patent optimizes the parameter of electronic conductive additive content to a specific range (0.5-60 wt%) to achieve the best balance between contact conductivity and discharge capacity. This parameter optimization ensures adequate conductivity without excessive additive content that would reduce the proportion of active silicon material.
Solution Approach 2:
The patent distributes electronic conductive additives locally within the composite particle structure rather than uniformly throughout, allowing concentrated conductivity enhancement at critical interfaces while minimizing the overall additive content to preserve discharge 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 proposed battery configuration enhances cycle life and discharge capacity by maintaining contact conductivity and preventing conductive pathway breakdown, resulting in improved performance compared to conventional lithium-ion batteries.
Implementation Method 1
it is very likely that the presence of the electronic conductive additive (B) and the carbon material (D) causes the enhancement of the contact conductivity between the silicon-containing particle A) and between the composite particle (C), respectively
Data Source
AI summary
The present invention provides a non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode having a negative active material, and a non-aqueous electrolyte; characterized in that said negative active material contains composite particle (C), which has silicon-containing particle (A) and electronic conductive additive (B), and carbon material (D), wherein the weight of said electronic conductive additive (B) falls within the range of 0.5 wt. % to 60 wt. % to the weight of said composite particle (C).The negative active material contains silicon which is capable of performing high discharge capacity, so that a non-aqueous electrolyte secondary battery having a large discharge capacity can be obtained. In addition, since the negative active material contains the electronic conductive additive (B) and the carbon material (D), the contact conductivity between the silicon-containing particle (A) or between the negative active material improves and, as a result, a non-aqueous electrolyte secondary battery having satisfactory cycle performance can be attained.