Sodium Tin Oxide Anodes for High-Density Sodium Batteries
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Solution Overview
Problem
Existing sodium secondary batteries using hard carbon-based negative electrodes suffer from low volumetric energy density and poor capacity retention due to the low density of carbon-based materials, while tin-based electrodes exhibit low first cycle reversible coulombic efficiency and significant volume changes during charge and discharge.
Innovation Solution
The use of sodium tin oxide (NaxSnOy) compounds, compositions, and composite materials as negative electrode active materials, which are amorphous and have specific molar ratios, improve electrical conductivity and mitigate volume changes, enhancing battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hard carbon-based negative electrode active material is used, then the battery structure is stable, but the volumetric energy density is low and capacity retention is poor
Solution Approach 1:
The patent changes the chemical composition parameters by using sodium tin oxide (NaxSnOy) with specific stoichiometric ratios (where 0.5 < x ≤ 1.5 and 1.5 < y ≤ 2.5) instead of conventional hard carbon. This parameter change enables both high volumetric energy density and good capacity retention by optimizing the Na:Sn:O ratio to achieve reversible sodium insertion/extraction while maintaining structural stability.
Solution Approach 2:
The patent employs composite material design by combining sodium, tin, and oxygen in specific proportions to form sodium tin oxide compounds. This composite approach leverages the high capacity of tin-based materials while using oxygen to mitigate volume expansion, thereby achieving both high volumetric energy density and improved capacity retention.
2Quantity of substance
If tin-based electrode material is used, then the volumetric energy density is high, but the first cycle reversible coulombic efficiency is low and volume changes significantly
Solution Approach 1:
The patent optimizes the stoichiometric parameters of sodium tin oxide by controlling the ratios of Na, Sn, and O atoms. By adjusting these parameters within specific ranges (0.5 < x ≤ 1.5 and 1.5 < y ≤ 2.5), the material achieves high volumetric energy density while improving first cycle reversible coulombic efficiency and reducing volume changes during cycling.
Solution Approach 2:
The patent introduces oxygen as an intermediary element in the sodium tin oxide structure. Oxygen acts as a mediator that buffers the volume expansion of tin during sodium insertion, thereby maintaining structural integrity and improving coulombic efficiency while preserving high volumetric energy density.
3Quantity of substance
If tin-based electrode material is used, then the volumetric energy density is high, but the volume changes significantly during charge and discharge
Solution Approach 1:
The patent creates a composite material system (sodium tin oxide) where oxygen is integrated into the tin-based structure. This composite design allows the material to maintain high volumetric energy density from the tin component while the oxygen component provides structural stability and mitigates volume changes during electrochemical cycling.
Solution Approach 2:
The patent modifies the compositional parameters by incorporating oxygen in specific amounts (1.5 < y ≤ 2.5 relative to Sn). This parameter adjustment transforms the material from pure tin (which undergoes large volume changes) to sodium tin oxide with controlled stoichiometry, achieving both high volumetric energy density and improved volume stability.
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 sodium tin oxide materials enhance battery capacity and density, achieving higher performance and smaller battery size by improving reversibility and reducing volume changes, with coulombic efficiencies above 95% in the first few cycles.
Implementation Method 1
improve electrical conductivity and mitigate volume changes, enhancing battery performance
Implementation Method 2
uses an organic liquid electrolyte to ensure sodium ionic conductivity between the positive electrode and the negative electrode
Implementation Method 3
Batteries comprise one or more electrochemical cell, such cells generally comprising a cathode, an anode and an electrolyte
Data Source
AI summary
Provided herein are high performance compounds, compositions, and composite materials of sodium (Na), tin (Sn), and oxygen (O). Electrodes and batteries incorporating the compounds, compositions, and composite materials are disclosed. Methods of manufacturing the compounds, compositions, and composite materials are also disclosed.