Silicon-Based Hydrogen Storage Electrodes for High Capacity
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Solution Overview
Problem
Conventional rechargeable metal hydride electrochemical cells have limitations in achieving lighter weight, higher capacity, and higher gravimetric energy density, particularly in their negative electrodes, which are typically based on heavy metal alloys like AB5 and A2B7.
Innovation Solution
The development of a rechargeable electrochemical cell utilizing a stable silicon-based hydrogen storage negative electrode with a solid electrolyte interface (SEI) capable of proton transport, incorporating modifying elements to enhance physical, chemical, and electrochemical properties, such as structural modifiers, hydrogen bond strength modifiers, and SEI modifiers, to achieve improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional metal hydride alloys (AB5, A2B7) are used for the negative electrode, then the electrode provides stable hydrogen storage capacity, but the electrode weight increases and gravimetric energy density decreases
Solution Approach 1:
The patent changes the fundamental material parameter from metal-based alloys to silicon-based materials, transitioning from heavy metal hydride chemistry to lighter silicon hydride chemistry. This parameter change enables achieving high discharge capacity (≥800 mAh/g) with significantly reduced electrode weight, directly resolving the contradiction between reliability and weight.
Solution Approach 2:
The patent employs composite material structures including silicon-based materials combined with modifying elements (B, alkaline earth metals, transition metals, rare earth metals) and carbon materials. These composites optimize both the hydrogen storage capacity and weight characteristics, achieving high gravimetric energy density while maintaining stable electrochemical performance.
2Weight of moving object
If silicon-based hydrogen storage material is used for the negative electrode, then the gravimetric energy density increases, but the electrode stability and cycle life may deteriorate
Solution Approach 1:
The patent introduces modifying elements as intermediaries between silicon and the electrolyte. Elements such as B, alkaline earth metals, transition metals, and rare earth metals form stable surface layers that mediate the interaction between silicon and the electrochemical environment, preventing direct degradation while maintaining hydrogen storage functionality. This intermediary layer ensures long-term stability and cycle life.
Solution Approach 2:
The patent applies different modifying elements at different locations and functions within the electrode structure. For example, boron may be used for structural modification, while rare earth metals provide surface stabilization. This localized optimization of material properties ensures both weight reduction and stability enhancement throughout the electrode.
3Productivity
If modifying elements are added to enhance electrode performance, then the discharge capacity and energy density improve, but the device complexity increases
Solution Approach 1:
The patent selects modifying elements that perform multiple functions simultaneously. For example, boron serves both as a structural modifier to stabilize the silicon phase and as an SEI modifier to improve interface stability. Rare earth metals provide both hydrogen bond strength modification and surface protection. This multi-functionality reduces the need for additional separate components, managing complexity while enhancing performance.
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 hydrogen storage negative electrode achieves a discharge capacity of ≥ 800 mAh/g over 20 charge/discharge cycles and exhibits a gravimetric energy density of > 100 Wh/kg and volumetric energy density of > 250 Wh/L, surpassing conventional metal hydride batteries.
Implementation Method 1
comprises a solid electrolyte interface (SEI) capable of allowing proton transport
Implementation Method 2
a negative electrode comprising a hydrogen storage material based on one or more group IV elements is highly effective as a hydrogen charge/discharge component
Implementation Method 3
The hydrogen storage material is for example based on silicon and/or carbon
Data Source
Figure 1
AI summary
Hydrogen storage negative electrodes based on group IV elements, for example hydrogen storage negative electrodes based on silicon and/or carbon, are highly effective towards reversibly charging/discharging hydrogen in an hydride electrochemical cell.