Bio-Derived SiOC Composite Anodes for Stable High-Capacity Batteries
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Solution Overview
Problem
Existing lithium ion batteries face challenges with high energy density and power density, particularly due to the limitations of graphite anodes, and silicon-based anodes suffer from significant expansion and stability issues, hindering their performance and lifespan.
Innovation Solution
A bioderived carbon-polymer derived ceramic composite electrode is formed by mixing bioderived carbon with a polymer derived ceramic resin, processed to create a SiOC ceramic composite with optimal specific surface area, which is then milled and used as an anode in lithium ion batteries, offering improved conductivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is added to graphite anodes to increase specific capacity, then the theoretical specific capacity increases, but the electrode expands and contracts by 300% during charge-discharge cycles, causing cracking and delamination that diminish battery lifetime
Solution Approach 1:
The patent applies this principle by coating silicon particles with a flexible carbonaceous material shell that can accommodate the 300% volume expansion during lithiation. This shell acts as a buffer that prevents cracking and delamination while allowing the silicon to expand and contract, thereby maintaining electrode integrity and extending battery lifetime despite the high capacity gains from silicon addition
Solution Approach 2:
The patent applies this principle by creating a composite anode structure that combines silicon particles with graphite and carbonaceous materials. This composite approach allows the system to benefit from silicon's high specific capacity (4200 mAh/g) while using graphite and carbon to provide structural stability and accommodate volume changes, thus resolving the contradiction between achieving high capacity and maintaining electrode stability
2Duration of action of stationary object
If LTO is used instead of graphite to achieve longer lifetime, then the battery lifetime increases, but the theoretical specific capacity decreases from 372 mAh/g to about 175 mAh/g
Solution Approach 1:
The patent applies this principle by merging multiple anode materials (graphite, silicon, and carbonaceous materials) into a single composite electrode structure. This combination allows the electrode to achieve both long cycle life (inherited from graphite's stability) and high specific capacity (contributed by silicon's 4200 mAh/g theoretical capacity), thereby resolving the trade-off between lifetime and capacity that exists when using LTO alone
3Reliability
If coal dust is used as carbon source for PDC composite electrodes, then the electrode performance is improved, but the carbon source depends on extraction of coal which is not renewable
Solution Approach 1:
The patent applies this principle by changing the parameter of carbon source from non-renewable coal dust to renewable biomass-derived carbon, while maintaining the electrochemical performance through optimized processing parameters such as pyrolysis temperature, carbonization conditions, and compositional ratios. This allows the system to achieve both renewability and reliable electrode 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 bioderived carbon composite electrodes achieve comparable energy and power densities to coal-derived sources, providing enhanced cycling stability and longer lifespan, utilizing renewable carbon sources effectively.
Implementation Method 1
a bioderived carbon source that, when mixed with a selected polymer derived ceramic resin and pyrolyzed, forms an electrically conductive ceramic composite
Data Source
AI summary
A composite electrode is made by combining a compatible polymer derived ceramic resin with a bioderived source of carbon and pyrolyzing the mixture. The resulting composite may be milled into a spherodized particulate powder and formed into an electrode of a battery with or without preionization of the electrode. For example, the bioderived source of carbon is selected from a polysaccharide.