Silicon Oxide Anode Composition for Uniform Current and Longer Cycle Life
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Solution Overview
Problem
Conventional lithium secondary batteries using silicon oxide-based negative electrodes face issues with low initial coulombic efficiency and poor battery life due to volume expansion and non-uniform current distribution, limiting their industrial usability and energy density.
Innovation Solution
A negative electrode comprising silicon oxide, lithium, and sodium/potassium, with specific elemental ratios, undergoes pre-lithiation and doping processes to enhance initial efficiency and life characteristics by ensuring uniform current distribution, utilizing lithium silicate and artificial graphite, and single-walled carbon nanotubes to improve performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based negative electrode material is used to increase energy density, then theoretical capacity increases from 372 mAh/g to 3580 mAh/g, but volume expansion reaches ~400% causing poor battery life
Solution Approach 1:
The patent uses a composite structure consisting of silicon oxide core particles coated with a lithium silicate layer. This composite material approach combines the high capacity of silicon-based materials with the volume stability of lithium silicate, achieving both high energy density and long cycle life by preventing the harmful volume expansion of pure silicon.
2Reliability
If silicon oxide-based negative electrode material is used to reduce volume expansion, then volume expansion rate decreases compared to Si, but initial coulombic efficiency becomes poor due to irreversible phase formation
Solution Approach 1:
The patent modifies the chemical composition and structure of the coating layer by controlling the lithium silicate formation through specific heat treatment parameters. By adjusting the lithium content and heat treatment conditions, the patent optimizes the balance between reducing irreversible phase formation and maintaining volume expansion control, thereby improving initial coulombic efficiency while preserving the volume stability benefits of silicon oxide.
3Reliability
If silicon oxide-based negative electrode material is used to reduce volume expansion, then volume expansion rate decreases, but electrical conductivity becomes low and current distribution becomes non-uniform
Solution Approach 1:
The patent applies a localized lithium silicate coating layer on the surface of silicon oxide particles. This creates a gradient structure where the core maintains the volume stability of silicon oxide while the surface coating provides enhanced electrical conductivity and uniform current distribution. The local modification of surface properties without altering the bulk composition resolves the contradiction between volume control and electrical conductivity.
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 approach significantly improves initial coulombic efficiency and battery life by optimizing elemental ratios and doping processes, leading to enhanced energy storage capabilities and industrial usability.
Implementation Method 1
a1) performing pre-lithiation by mixing a silicon-based material including a silicon oxide and a lithium precursor and heat treating the mixture to dope the silicon-based material with lithium
Implementation Method 2
heat treating the mixture to dope the silicon-based material with lithium
Data Source
AI summary
Provided are a negative electrode for a lithium secondary battery and a method of manufacturing the same. The negative electrode for a lithium secondary battery according to an embodiment of the present invention includes a negative electrode active material including: a silicon oxide, lithium, and sodium and/or potassium, wherein in ICP analysis of a negative electrode active material layer including the negative electrode active material, contents of elements in the negative electrode active material layer satisfy the following Relations (1) and (2): 300≤106*A/B2+C2≤12.0*106 800≤A≤140,000 wherein A is a Li content in ppm, B is a Na content in ppm, and C is a K content in ppm, based on the total weight of the ICP-analyzed negative electrode active material layer.