Multilayer Silicon Anode Structure to Prevent Pulverization
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Solution Overview
Problem
Existing silicon anodes in lithium-ion batteries face issues such as high volume expansion, pulverization, loss of electrical contact, unstable surface, and poor conductivity due to the brittle nature of silicon, limiting their capacity and stability during lithium intercalation.
Innovation Solution
A silicon electrode with a multistratum structure comprising a copper current collector, an adhesion layer, and a conductive metal silicide matrix formed through rapid thermal annealing, which includes alternating layers of silicon and metal or a mixed system, ensuring stable adhesion and high electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as anode material to achieve high storage capacity, then capacity is improved, but volume expansion and pulverization occur during charging and discharging
Solution Approach 1:
The silicon anode is segmented into multiple thin strata (alternating silicon and metal layers) rather than using a single thick layer. This segmentation allows each thin stratum to accommodate volume expansion independently without causing overall structural failure, resolving the contradiction between achieving high capacity (requiring thick silicon) and maintaining structural stability.
Solution Approach 2:
The invention creates a composite structure by alternating silicon strata with metal strata (such as copper, aluminum, or titanium). The metal layers provide mechanical strength and structural stability while the silicon layers provide high lithium storage capacity. This composite approach allows the anode to achieve both high capacity and structural stability during cycling.
2Quantity of substance
If thick silicon layer is applied to increase capacity, then areal capacity is improved, but electrical contact is lost due to pulverization
Solution Approach 1:
The thick silicon layer is divided into multiple thin strata separated by conductive metal layers. Each thin silicon stratum maintains good electrical contact with the current collector through the adjacent metal layers, preventing the loss of electrical contact that occurs in thick monolithic silicon structures during pulverization.
Solution Approach 2:
The metal strata act as intermediary layers between the silicon active material and the current collector. These metal intermediaries maintain continuous electrical pathways even when silicon undergoes volume changes, ensuring reliable electrical contact is preserved throughout cycling while achieving high areal capacity.
3Quantity of substance
If pure silicon is used to achieve high capacity, then storage capacity is improved, but conductivity is reduced due to semiconductor properties
Solution Approach 1:
The alternating silicon and metal strata create a composite structure where the metal layers (copper, aluminum, or titanium) provide high electrical conductivity pathways. The silicon layers contribute high storage capacity while the metal layers compensate for silicon's poor conductivity, achieving both high capacity and good power performance.
Solution Approach 2:
The metal strata serve multiple functions simultaneously: they provide electrical conductivity to compensate for silicon's semiconductor properties, offer mechanical strength to prevent pulverization, and act as diffusion barriers to control lithium insertion. This multi-functionality allows the structure to achieve high capacity while maintaining good conductivity.
4Quantity of substance
If silicon anode is used to improve capacity, then energy density is improved, but surface instability causes continuous SEI formation
Solution Approach 1:
The silicon surface is segmented into thin strata rather than a continuous thick layer. This segmentation creates multiple stable interfaces with the electrolyte, reducing the total surface area exposed to electrolyte decomposition and minimizing continuous SEI formation while maintaining high energy density.
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 solution provides a silicon anode with a specific capacity over 2000 mAh/g, maintaining electrical contact and stability during cycling, reducing the formation of a solid electrolyte interface, and enabling high charge rates without capacity loss, thus enhancing battery performance.
Implementation Method 1
the multistratum structure being subjected to rapid thermal annealing and forming a conductive metal silicide matrix
Implementation Method 2
formed from at least one stratum composed of a metal and silicon or is formed from a mixed system consisting of silicon admixed with at least one metal
Implementation Method 3
forming a conductive metal silicide matrix
Data Source
AI summary
The invention relates to a silicon electrode suitable for use as an anode in a lithium ion battery, comprising a current collector, preferably made of copper, an adhesive layer arranged on the current collector, and a multi-layer structure arranged on the adhesive layer. The object of providing an Si electrode, which is not pulverised when lithium is incorporated and therefore does not lose the electrical contact with the current collector as a result, as well as having a stable surface and high intrinsic conductivity, is achieved in that the multi-layer structure, as an active layer of the Si electrode, is formed by at least one layer made of a metal and silicon or formed by a mixed system consisting of silicon mixed with at least one metal, wherein the multi-layer structure undergoes rapid tempering and forms a conductive metal silicide matrix, wherein the metal silicide matrix contains amorphous, nanocrystalline regions of the silicon.