Amorphous Silicon Oxide Anode Material for Stable Li-Ion Cycling
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Solution Overview
Problem
Conventional lithium batteries using metallic lithium anodes face issues such as dendrite formation, instability, and low capacity due to porosity in carbonaceous anodes, while materials like silicon and tin alloys suffer from volumetric expansion and irreversible capacity, hindering the development of high-capacity lithium-ion batteries.
Innovation Solution
A silicon oxide-based composite anode active material with an amorphous structure, characterized by specific X-ray photoelectron spectrometry peaks, is developed by sintering hydrogen silsesquioxane at high temperatures, which enhances lithium ion intercalation and deintercalation efficiency and reduces irreversible capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metallic lithium is used as anode material to achieve high initial battery capacity, then battery capacity is improved, but dendrite formation and internal shorts occur degrading charge-discharge efficiency and safety
Solution Approach 1:
A lithium fluoride (LiF) coating layer is introduced as an intermediary between the silicon oxide anode and the electrolyte. This coating layer acts as a protective barrier that prevents direct contact between lithium and the electrolyte, thereby eliminating dendrite formation and internal shorts while maintaining high battery capacity. The LiF coating is formed by reacting silicon oxide with lithium fluoride at high temperature (900-1300°C), creating a stable interface that ensures safe and efficient charge-discharge cycles.
2Reliability
If carbonaceous materials are used as anode materials to eliminate metallic lithium problems, then safety is improved, but battery capacity decreases due to porosity
Solution Approach 1:
A composite anode material is developed consisting of silicon oxide particles embedded in a carbonaceous matrix. The silicon oxide provides high theoretical capacity (exceeding 3860 mAh/g when fully lithiated to form Li22Si5O29), while the carbonaceous material ensures safety by preventing dendrite formation and providing structural stability. The composite structure allows lithium ions to intercalate into the silicon oxide phase, achieving both high capacity and safety characteristics.
3Quantity of substance
If materials that can alloy with lithium (Si, Sn, Al) are used as anode active materials to improve battery capacity, then battery capacity is improved, but volumetric expansion occurs during formation of lithium alloy
Solution Approach 1:
The invention changes the oxidation state parameter of silicon from elemental silicon (Si⁰) to silicon oxide (Si⁴⁺). This parameter change fundamentally alters the volume expansion behavior during lithium alloying. While elemental silicon expands by approximately 300% when forming Li15Si4, silicon oxide exhibits significantly reduced volumetric expansion because the silicon is already in its oxidized state and forms a different lithiated phase (Li22Si5O29) with more moderate volume changes. This parameter change enables high capacity while maintaining structural integrity.
4Volume of moving object
If silicon oxide is used as anode material to reduce volumetric expansion, then volumetric expansion is reduced, but irreversible capacity increases during initial charge-discharge cycling
Solution Approach 1:
A lithium fluoride (LiF) coating layer is introduced as an intermediary between the silicon oxide anode and the electrolyte. This coating layer serves multiple functions: (1) It acts as a protective barrier that prevents electrolyte decomposition and formation of thick solid electrolyte interphase (SEI) layers, thereby reducing irreversible capacity loss; (2) It facilitates lithium ion transport during initial cycles; (3) It maintains the structural integrity of silicon oxide particles during volume changes. The LiF coating is formed by reacting silicon oxide with lithium fluoride at high temperature (900-1300°C), creating a stable and conductive interface that minimizes energy loss during initial charge-discharge cycling.
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 novel anode active material improves charge and discharge efficiency, capacity retention, and cycling characteristics of lithium batteries, enabling higher energy density and stability compared to conventional silicon oxide-based anodes.
Implementation Method 1
sintering hydrogen silsesquoxane at high temperatures
Implementation Method 2
sintering hydrogen silsesquoxane at high temperatures
Implementation Method 3
lithium ions in the electrolytic solution intercalate/deintercalate in the carbonaceous material
Data Source
AI summary
Silicon oxide based composite anode active materials including amorphous silicon oxides are provided. In one embodiment, the amorphous silicon oxide is represented by SiOx (where 0<x<2), has a binding energy of about 103 to about 106 eV, a silicon peak with a full width at half maximum (FWHM) ranging from about 1.6 to about 2.4 as measured by X-ray photoelectron spectrometry, and an atomic percentage of silicon greater than or equal to about 10 as calculated from an area of the silicon peak. The anode active material is a composite anode active material obtained by sintering hydrogen silsesquioxane (HSQ). Anodes and lithium batteries including the anode active material exhibit improved charge and discharge characteristics.