Silicon Anode Coating with Metal Powder for Over-Discharge Safety
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-ion secondary batteries using silicon-based materials face safety issues due to the formation of a solid electrolyte interface film that decomposes, leading to potential short circuits and degradation in safety performance.
Innovation Solution
Incorporating a metal powder with an electrode potential between 1.6 and 3.5 V into the negative electrode plate, along with a silicon-based material, to ensure metal evolution occurs before reaching the copper foil, causing a controlled short circuit and passing the over-discharge test without affecting capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon-based materials are used as negative electrode active material to meet high energy density requirements, then energy density is improved, but safety performance deteriorates due to SEI film formation and decomposition causing heat release
Solution Approach 1:
The patent introduces a metal powder with specific electrode potential (1.5-3.5V vs Li/Li+) that will oxidize first during over-discharge, converting the harmful over-discharge condition into a beneficial protective mechanism. The metal powder acts as a sacrificial component that triggers controlled short circuit before the copper current collector can oxidize, thereby preventing thermal runaway while maintaining high energy density from silicon-based materials
2Reliability
If metal powder with electrode potential between 1.5 and 3.5 V is added to enable over-discharge protection, then safety performance is improved, but device complexity increases due to additional components and composition control
Solution Approach 1:
The patent specifies precise parameter ranges for the metal powder (electrode potential 1.5-3.5V vs Li/Li+, content 1-20 wt%) to achieve the protective function. By controlling these parameters, the system achieves over-discharge protection without requiring complex structural modifications, maintaining relatively simple device architecture while improving safety
Solution Approach 2:
The negative electrode plate is designed as a composite material system combining silicon-based active material with metal powder additives. This composite approach integrates the high capacity of silicon with the protective oxidation characteristics of the metal powder, achieving both high energy density and enhanced safety through material composition rather than structural complexity
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 solution enhances safety performance by ensuring the lithium-ion secondary battery passes the over-discharge test without capacity loss, while maintaining high energy density.
Implementation Method 1
the metal powder can be oxidized to metal ions prior to a copper foil current collector
Implementation Method 2
the metal ions pass through a separator to allow reduction and metal evolution on the surface of the positive electrode plate
Implementation Method 3
the separator is pierced, causing a short circuit in the lithium-ion secondary battery
Data Source
AI summary
A negative electrode plate includes a current collector and a coating applied to at least one surface of the current collector, the coating comprising a negative electrode active material and a metal powder, wherein the electrode potential of the metal powder in the coating relative to lithium may be between 1.6 and 3.5 V, the negative electrode active material may be a silicon-based material, and relative to the total weight of the silicon-based material and the metal powder, the proportion by weight of the metal powder may be 5 to 20% and the proportion by weight of the silicon-based material may be 80 to 95%.