Silicon-Silicon Oxide-Lithium Composite Anode for Battery Volume Stability
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Solution Overview
Problem
Silicon-based anodes for lithium-ion batteries face challenges such as high irreversible capacity loss, poor cyclic performance, and significant volume change during charge-discharge cycles, which limit their energy density and compatibility with conventional manufacturing processes due to high chemical reactivity.
Innovation Solution
A silicon-silicon oxide-lithium composite material with nano silicon particles embedded in a porous, plastically deformable silicon-lithium silicate matrix is produced through a cyclical ex situ prelithiation-delithiation process, minimizing volume change and enhancing cyclic stability, and is delithiated before use to reduce reactivity and improve compatibility with battery manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon anode loading density is increased to increase energy density, then battery energy density improves, but electrode collapse occurs and cyclic performance deteriorates
Solution Approach 1:
A flexible polymer binder system is used to create a resilient matrix that can accommodate silicon's volume expansion and contraction during lithiation-delithiation cycles. The binder forms a flexible coating around silicon particles, maintaining electrode structural integrity even at high loading densities, thereby preventing electrode collapse while preserving cyclic performance.
Solution Approach 2:
The invention creates a composite anode structure combining silicon particles with a polymer binder matrix and conductive carbon network. This composite architecture allows the silicon to expand and contract within the flexible polymer framework, maintaining both high energy density and structural stability for improved cyclic performance.
2Stability of the object's composition
If silicon anode volume expansion is accommodated by increasing packaging structure size, then volume change during cycling is managed, but battery packaging structure becomes larger than desired
Solution Approach 1:
The flexible polymer binder creates a compliant matrix that dynamically adapts to silicon's volume changes during cycling. This flexible framework allows the anode to expand and contract in-situ without requiring excessive clearance in the packaging structure, maintaining volume stability while minimizing overall battery size.
Solution Approach 2:
The polymer binder system provides dynamic mechanical properties that allow the anode structure to flex and adapt during lithiation-delithiation cycles. This dynamic response enables the electrode to accommodate volume changes internally rather than requiring fixed external constraints, reducing packaging structure volume.
3Reliability
If prelithiated anode material is used to reduce irreversible capacity loss, then capacity retention improves, but chemical reactivity increases and compatibility with manufacturing processes decreases
Solution Approach 1:
The polymer binder is applied to silicon particles before lithiation, creating a protective flexible coating that moderates the chemical reactivity of prelithiated material. This preliminary bonding allows the use of prelithiated silicon (which has reduced irreversible capacity loss) while the polymer matrix controls its reactivity, maintaining compatibility with conventional manufacturing processes.
Solution Approach 2:
The polymer binder acts as an intermediary between the highly reactive prelithiated silicon particles and the manufacturing environment. This flexible polymer layer mediates the chemical interactions, reducing the direct reactivity of prelithiated silicon with moisture and other substances in the manufacturing process while still allowing lithium ion transport.
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 process results in a composite that achieves reduced volume change, improved cyclic performance, and increased energy density, with a reversible capacity greater than 1100 mAh/g and irreversible capacity loss less than 15%, making it suitable for high-energy-density lithium-ion batteries with reduced manufacturing complexities.
Implementation Method 1
The very large volume change leads to mechanical failure and capacity fading. Moreover, for an as-fabricated battery having a silicon anode, the battery packaging structure or container must be sufficiently large to accommodate the maximum volumetric expansion exhibited by the silicon anode material therein
Implementation Method 2
producing a further prelithiated SSLC material by way of a spontaneous lithiation procedure including: compressing the partially prelithiated SSLC material matrix material; and exposing the compressed partially prelithiated SSLC material to a lithium based electrolyte, wherein spontaneous lithiation procedure completes reaction of unreacted lithium and SiOx in the partially prelithiated SSLC material, until unreacted lithium disappears and a uniform composition of lithium silicides is achieved in the SSLC material by lithium diffusion
Data Source
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Figure 3A~3C
AI summary
A method for producing a volume change compensated silicon: silicon oxide: lithium composite (SSLC) material is disclosed. The method includes producing an initially prelithiated SSLC material; delithiating the initially prelithiated material to produce a delithiated SSLC material; and performing at least one iteration of a volume change compensation process involving: (a) re-prelithiating the delithiated SSLC material to produce a re-prelithiated SSLC material; and (b) delithiating the re-prelithiated SSLC material produced in (a), wherein at least one of the following is satisfied: (i) prior to performing the at least one iteration of the volume change compensation process the initially prelithiated SSLC material is essentially completely lithiated; and (ii) at least one iteration of the volume change compensation process produces a re-prelithiated SSLC material that is essentially completely prelithiated. In a final iteration of the volume change compensation process, delithiating the re-prelithiated SSLC material produced in (a) completely delithiates the re-prelithiated SSLC material to produce the volume change compensated SSLC material. The aforesaid process is performed prior to, or ex situ with respect to, the fabrication of an anode that contains the produced volume change compensated SSLC material.