SiO Anode Conductive Polymer Binder and SLMP Prelithiation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current lithium-ion battery electrodes, particularly those using silicon (Si) as an alloying material, face challenges with high volume expansion leading to structural instability, low power rate, and short cycle life due to material instability and poor electron and ion conduction, limiting their energy density and lifespan.
Innovation Solution
The use of silicon monoxide (SiO) with a conductive polymer binder, such as Poly (9,9-dioctylfluorene-co-fluorenone-co-methylbenzoic ester) (PFM), and Stabilized Lithium Metal Powder (SLMP) prelithiation, which enhances adhesion and electronic conduction, reduces volume expansion, and improves the first-cycle coulombic efficiency, allowing for higher active material loading and extended cycling stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon (Si) is used as an alloying electrode material to achieve high theoretical charge capacity, then the charge capacity is improved, but the volume expansion and structural instability worsen
Solution Approach 1:
The silicon is divided into nanoscale domains (5-50 nm) dispersed within a silicon oxide matrix, rather than using bulk silicon. This segmentation reduces the volume expansion stress on any single domain and prevents catastrophic structural failure during lithiation/delithiation cycles.
Solution Approach 2:
Silicon nanodomains are embedded within the silicon oxide matrix, creating a core-shell like structure where the stable SiO2 matrix contains and protects the reactive Si domains. This nested structure allows the high-capacity Si to be protected by the stable SiO2 framework.
2Ease of manufacture
If conventional polymer binders are used in silicon electrodes, then the manufacturing process is simplified, but the electronic conduction and adhesion worsen
Solution Approach 1:
The binder is a composite material combining a conventional polymer matrix with conductive additives (carbon black, graphite, or conductive polymers). This composite structure provides both the mechanical adhesion of the polymer and the electronic conduction of the conductive additives, resolving the contradiction between ease of manufacture and electrical performance.
3Reliability
If high concentrations of inactive materials (binder and conductive additives) are used to ensure adhesion and conduction, then the electrode integrity is improved, but the energy density worsens
Solution Approach 1:
The electrode is designed with a porous structure where silicon nanodomains are dispersed within the silicon oxide matrix. This porous architecture provides sufficient surface area for adhesion and conduction pathways while minimizing the volume occupied by inactive materials, thereby maintaining high energy density.
4Duration of action of stationary object
If silicon nanostructures are used to address volume expansion, then the capacity retention is improved, but the manufacturing complexity and cost worsen
Solution Approach 1:
The invention changes the compositional parameter from pure silicon to silicon oxide with controlled Si nanodomain distribution. This parameter change achieves the volume expansion mitigation of silicon nanostructures while using a more manufacturable material system that can be produced through conventional ceramic processing techniques.
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
This approach enables SiO electrodes to maintain a reversible capacity of 1000 mAh/g for over 400 cycles with 2% PFM binder and 90% capacity retention after 100 cycles, significantly improving energy density and cycle life compared to graphite electrodes, while minimizing irreversible capacity loss.
Implementation Method 1
strong adhesion of covalent functionality and electronic conduction of functional conductive polymer binder
Implementation Method 2
electronic conduction of functional conductive polymer binder
Implementation Method 3
Stabilized Lithium Metal Power (SLMP) prelithiation, which enhances adhesion and electronic conduction, reduces volume expansion, and improves the first-cycle coulombic efficiency
Implementation Method 4
Si as an alloying electrode material is attracting much attention because it has the highest known theoretical charge capacity (4200 mA h g−1)
Data Source
AI summary
The invention demonstrates that only 2% functional conductive polymer binder without any conductive additives was successfully used with a micron-size silicon monoxide (SiO) anode material, demonstrating stable and high gravimetric capacity (>1000 mAh/g) for ˜500 cycles and more than 90% capacity retention. Prelithiation of this anode using stabilized lithium metal powder (SLMP®) improves the first cycle Coulombic efficiency of a SiO/NMC full cell from ˜48% to ˜90%. This combination enables good capacity retention of more than 80% after 100 cycles at C/3 in a lithium-ion full cell. We also demonstrate the important connection between porosity and the loading of silicon electrodes. By employing a highly porous silicon electrode, a high areal capacity (3.3 mAh/cm2) is obtained. This method works well to achieve high loading of other high-capacity alloy anodes, the state-of-art graphite anode, as well as a high loading of positive electrodes for LIBs.