Double-Layer Lithium Battery Anode for Fast Charging and Cycle Life
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Solution Overview
Problem
Lithium secondary batteries using silicon-based negative electrodes face challenges with rapid volume expansion during charging, leading to conductive path disconnection, surface degradation, and reduced cycle life, especially when high-capacity silicon-based compounds are used.
Innovation Solution
A negative electrode structure with a double-layer active material layer, comprising a carbon-based active material in the first layer and a silicon-based active material in the second layer, with the silicon-based material coated thinly to maximize rapid charging performance while suppressing volume expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If silicon-based active material is used to increase capacity, then rapid charging performance is improved, but volume expansion occurs during charging leading to conductive path disconnection
Solution Approach 1:
A thin film coating layer is formed on the silicon-based active material particles. This coating layer acts as a protective shell that accommodates volume expansion during charging while maintaining structural integrity and preventing conductive path disconnection. The thin film structure allows the silicon particles to expand and contract without breaking the conductive network.
Solution Approach 2:
The negative electrode uses a composite structure combining silicon-based active material particles with a coating layer material. This composite approach leverages the high capacity of silicon while the coating layer provides mechanical stability and prevents structural collapse during volume changes, resolving the contradiction between capacity and reliability.
2Quantity of substance
If silicon-based compound is used to increase capacity, then discharge capacity is improved, but surface degradation accelerates due to non-uniform lithium ion charging
Solution Approach 1:
The coating layer serves as an intermediary between the silicon-based active material and the electrolyte. This intermediate layer promotes more uniform lithium ion distribution during charging by preventing direct contact between the electrolyte and silicon surface, thereby reducing non-uniform charging effects and surface degradation while preserving high capacity.
3Quantity of substance
If high-capacity silicon-based material is used, then energy density is improved, but cycle life decreases due to structural change and collapse
Solution Approach 1:
The coating layer is applied beforehand to the silicon-based active material particles to provide structural support and prevent collapse during cycling. This pre-protective structure cushions the silicon particles against repeated volume changes during charging and discharging, maintaining structural integrity over multiple cycles while preserving high energy density.
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 structure enhances both rapid charging performance and cycle life by minimizing lithium precipitation and surface degradation, effectively addressing the limitations of silicon-based negative electrodes.
Implementation Method 1
The negative electrode includes a negative electrode active material for intercalating and deintercalating lithium ions to and from the positive electrode
Implementation Method 2
the fields that are being studied most actively are the fields of power generation and power storage using an electrochemical reaction
Data Source
AI summary
A negative electrode for a lithium secondary battery, a method for manufacturing the same, and a lithium secondary battery including the same are provided. The negative electrode includes a first negative electrode active material layer having a first negative electrode active material comprising one or more selected from the group consisting of a carbon-based active material, a silicon-based active material, a metal-based active material capable of forming an alloy with lithium, and a lithium-containing nitride; and a second negative electrode active material layer having a second negative electrode active material comprising one or more selected from the group consisting of Si, SiOx (0<x<2), and SiC, wherein the negative electrode satisfies 0.1≤[B/(A+B)]×100(%)≤15, where A is a total thickness of the first negative electrode active material layer and is 30 μm or greater and 150 μm or less, and B is a total thickness of the second negative electrode active material layer.