Multilayer Nanostructured Templates for High-Capacity Battery Electrodes
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Solution Overview
Problem
High capacity electrochemically active materials in batteries experience substantial volume changes during cycling, leading to pulverization and loss of electrical connections, which limits their cycling performance and capacity retention.
Innovation Solution
The development of battery electrode structures with high mass loadings of high capacity active materials, utilizing multiple template layers with controlled density and porosity, and a coating of electrochemically active materials that maintain electrical connections and mechanical support, including layers of metal silicides and carbon nanofibers, to enhance active material loading and cycling stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high capacity active materials are used to increase battery capacity, then the capacity per unit mass increases, but the materials undergo substantial volume changes during cycling causing pulverization and loss of electrical connections
Solution Approach 1:
The patent divides the active material into discrete nanoscale particles or structures (e.g., silicon nanowires, nanospheres, or nanocrystals) rather than using bulk material. This segmentation allows each nanoscale unit to independently accommodate volume changes during lithiation/delithiation cycles, preventing the pulverization that occurs in bulk materials while maintaining high capacity.
Solution Approach 2:
The patent introduces an intermediary buffer layer or coating (such as carbon coatings, oxide layers, or polymer matrices) around the high capacity active material nanosstructures. This intermediary layer acts as a mechanical buffer that absorbs and distributes the stress from volume changes, preventing direct contact between pulverized particles and maintaining electrical connections throughout cycling.
2Reliability
If nanostructures are used to reduce volume change damage, then cycling stability improves, but integrating multiple nanostructures into electrode layers with adequate active material loadings becomes difficult
Solution Approach 1:
The patent employs a hierarchical nested structure where nanoscale active material particles are embedded within a mesoscale conductive matrix or scaffold, which itself is integrated into the macroscale electrode layer. This nested architecture allows adequate active material loading at each scale while maintaining the cycling stability benefits of nanosstructures and simplifying integration through self-assembly or controlled deposition processes.
Solution Approach 2:
The patent utilizes porous conductive matrices or scaffolds (such as carbon foams, porous oxides, or interconnected nanofiber networks) with controlled porosity and surface area. These porous materials provide numerous anchoring sites for nanoscale active materials, facilitate electrolyte penetration and ion transport, and accommodate volume changes through their compressible porous structure, thereby simplifying the integration of high loadings of nanosstructures into functional electrode layers.
3Reliability
If nanofilms are deposited on conventional flat substrates to use nanostructures, then volume change damage is reduced, but adequate active material loading is not achieved because the nanofilm must be kept thin
Solution Approach 1:
The patent transitions from two-dimensional flat nanofilms on conventional substrates to three-dimensional nanoscale structures (such as nanowires, nanospheres, nanocrystals, or hierarchical assemblies) with significant volume-to-surface-area ratios. This dimensional change allows the active material to be distributed throughout a three-dimensional space, achieving adequate loading while maintaining thin overall electrode profiles and the structural integrity benefits of nanoscale dimensions that accommodate volume changes.
Data Source
AI summary
Provided are battery electrode structures that maintain high mass loadings (i.e., large amounts per unit area) of high capacity active materials in the electrodes without deteriorating their cycling performance. These mass loading levels correspond to capacities per electrode unit area that are suitable for commercial electrodes even though the active materials are kept thin and generally below their fracture limits. A battery electrode structure may include multiple template layers. An initial template layer may include nanostructures attached to a substrate and have a controlled density. This initial layer may be formed using a controlled thickness source material layer provided, for example, on a substantially inert substrate. Additional one or more template layers are then formed over the initial layer resulting in a multilayer template structure with specific characteristics, such as a surface area, thickness, and porosity. The multilayer template structure is then coated with a high capacity active material.