Silicon-Based Anode Material for Li-Ion Batteries
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Solution Overview
Problem
Conventional silicon-based negative electrode materials for lithium-ion batteries suffer from poor coulombic efficiency, capacity retention, and rate capability due to the formation of a solid electrolyte interface that consumes lithium ions and causes volume expansion, leading to disintegration during charge and discharge cycles, especially at high C-rates.
Innovation Solution
A silicon-based material with specific X-ray diffraction peak characteristics is developed by mixing a metal source compound, a carbon source compound, and a silicon oxide raw material with water and subjecting the mixture to heat treatment, resulting in a material with improved alkalinity and structural stability, allowing for higher coulombic efficiency and capacity retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon-based material is used as negative electrode material to increase theoretical capacity, then energy density is improved, but first coulombic efficiency deteriorates due to SEI formation consuming lithium ions
Solution Approach 1:
The invention changes the chemical composition parameters of the silicon-based material by incorporating specific metal elements (Li, Na, K, Ca, Sr, or Ba) at controlled concentrations (0.1-10 wt%). This parameter modification adjusts the material's electrochemical properties to reduce SEI formation and improve first coulombic efficiency while maintaining high energy density
Solution Approach 2:
The invention creates a composite silicon-based material by combining silicon with metal oxides or hydroxides of alkali or alkaline earth metals. This composite structure leverages the high capacity of silicon while the metal components mitigate SEI formation, achieving both high energy density and improved coulombic efficiency
2Quantity of substance
If silicon-based material undergoes intercalation and deintercalation of lithium ions during charge and discharge, then battery capacity is achieved, but volume expansion and contraction cause structural disintegration
Solution Approach 1:
The composite structure of silicon with metal oxides/hydroxides provides a more stable framework that accommodates volume changes during lithium ion intercalation/deintercalation. The metal components act as structural buffers that prevent disintegration while allowing battery capacity to be achieved
Solution Approach 2:
By modifying the chemical composition and crystal structure parameters of the silicon-based material through metal element incorporation, the invention creates a more resilient structure that can withstand repeated volume expansion and contraction cycles without disintegrating
3Speed
If conventional silicon-based material is used for fast charge and discharge at high C-rate, then rate capability is tested, but structural disintegration becomes more prominent affecting capacity retention
Solution Approach 1:
The invention optimizes the chemical composition parameters (metal element type and concentration) to enhance the material's response to high-rate charge/discharge operations. This allows the material to maintain structural integrity and capacity retention even at high C-rates
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 silicon-based material exhibits enhanced first coulombic efficiency, high capacity retention, and improved rate capability, increasing energy density by at least 15% and maintaining >80% capacity after 800 cycles, with excellent fast charge performance and improved operability compared to conventional materials.
Implementation Method 1
subjecting the aqueous mixture to heat treatment
Implementation Method 2
The X-ray diffraction pattern obtained using Cu Kα rays of the silicon-based material has the following characteristic peaks
Data Source
AI summary
The invention provides a silicon-based material and a method for producing the same. In all X-ray diffraction pattern obtained by using Cu Kα rays, the silicon-based material includes the following characteristic peaks: (A) a characteristic peak at 2θ=23°±1° with an intensity IA; (B) a characteristic peak at 2θ=28°±0.5° with an intensity IB; (C) a characteristic peak at 2θ=48°±1° with an intensity IC; and (D) a characteristic peak at 2θ=56°±1° with an intensity ID, wherein: 1.2≤IB/IA≤1.7; 1.8≤IB/IC≤2.3; and 1.6≤IB/ID≤3.0. The present invention also provides a battery negative electrode including the silicon-based material.