Imagine a phone battery that could charge faster, last longer, and remain durable even after years of use. This is the goal being pursued by materials researchers around the world, including Dr. drg. Bambang Priyono, S.U., and a team from the Department of Metallurgical and Materials Engineering at Universitas Indonesia. In a study presented at the i-TREC 2018 international conference, they investigated a new combination of anode materials for lithium-ion batteries: activated carbon combined with silicon oxycarbide (SiOC). The results open up promising opportunities for developing more reliable batteries, particularly for electronic devices, electric vehicles, and renewable energy storage systems.
The Long-Standing Problem Behind Modern Batteries
Lithium-ion batteries have long been the backbone of modern technology. From smartphones and laptops to electric scooters and solar power systems, almost everything relies on this technology. However, one fundamental challenge remains unresolved: silicon-based anode materials.
Silicon has tremendous potential. Its theoretical capacity reaches 4,200 mAh/g, far exceeding that of graphite, which has traditionally been the industry standard. The problem is that silicon expands by more than 300% during battery charging and discharging. Such substantial expansion causes electrodes to crack, reduces capacity, and accelerates battery degradation.
The solution proposed by the research team is conceptually simple but technically complex: encapsulating silicon with carbon. More specifically, they synthesized silicon oxycarbide (SiOC) and combined it with activated carbon as a supporting layer. This composite material was designated SiOC@C.
The Complex Process Behind the Black Powder
Producing SiOC@C is no simple task. The process involved two synthesis stages, each requiring a high degree of precision.
Activated carbon was prepared from commercially available carbon powder, which was heated, immersed in a NaOH solution, and then heated again under a nitrogen gas flow at 700°C. The carbon was subsequently rinsed with HCl solution and hot water until the pH reached 6.5. The resulting porous carbon had a substantially larger surface area, increasing from 224.847 m²/g before activation to 490.007 m²/g afterward.
Meanwhile, SiOC was synthesized from phenyl-rich silicone oil through pyrolysis at 900°C under an argon gas flow. The two materials were then mixed with SiOC concentrations of 4 wt.% and 10 wt.% before being fabricated into coin-cell electrodes for testing.
The result? A black powder with a slight metallic sheen and considerable potential.
The Numbers Speak for Themselves
The researchers used a series of characterization methods, including BET to measure surface area, SEM-EDS to examine morphology, XRD to analyze crystal phases, and cyclic voltammetry (CV), charge-discharge testing, and electrochemical impedance spectroscopy (EIS) to evaluate battery performance.
The sample containing 10 wt.% SiOC demonstrated the best performance across nearly all parameters. Its surface area reached 542.738 m²/g, its highest discharge capacity was 223.3 mAh/g, and its resistance was the lowest at 84.86 Ω. Lower resistance indicates higher electrical conductivity, meaning that lithium-ion transfer occurs more efficiently.
“The highest specific surface area, discharge capacity, and conductivity is obtained in 10wt.% SiOC sample.” — Dr. drg. Bambang Priyono, S.U., et al., E3S Web of Conferences, 2018
The porous structure observed in the SEM images further supported these findings. Small pores within the material shorten the distance traveled by lithium ions, allowing charging and discharging to occur more rapidly.
One interesting anomaly emerged at a low C-rate in the 7 wt.% sample, where the discharge capacity unexpectedly increased to 247 mAh/g. This phenomenon requires further investigation and opens up opportunities for future research.
The Long Road Toward Better Batteries
This research has not yet produced a commercial product. The researchers themselves acknowledged several limitations that still need to be addressed, including imperfect coulombic efficiency caused by the formation of the solid electrolyte interface (SEI) layer and irreversible trapping of lithium ions.
Nevertheless, the direction of the research is clear: SiOC@C is a serious candidate for replacing graphite as the anode material in next-generation lithium-ion batteries. If these technical challenges can be overcome, the impact could extend across consumer electronics, electric vehicles, and energy storage systems powered by renewable sources such as wind and solar.
As the global energy transition becomes increasingly urgent, research such as this is more than an academic exercise. It is part of the foundation being built to enable the world to move away from its dependence on fossil fuels.
Authors: Achmad Zam Zam Aghasy, DDS, M.Kes.; Hazra Alifia Muharam
Photo: Freepik
Source DOI: https://doi.org/10.1051/e3sconf/20186703027