Sodium-ion batteries are potentially a safer and less expensive alternative to lithium-ion batteries for large-scale energy storage, but current versions don't last long enough yet for practical use.
Lithium and sodium have similar properties in many ways, but sodium ions are much larger than lithium ions. Large volume change and sluggish diffusion kinetics are generally considered to be responsible for sodium-ion batteries’ fast capacity degradation.
The researchers developed a simple approach to making a high performance anode material by binding an antimony-based mineral onto sulphur-doped graphene (SGS) sheets.
Computational calculations are said to demonstrate that SGS has a stronger affinity for antimony sulphide than pure graphene, resulting in a robust composite architecture.
According to the team, incorporating the anode into a sodium-ion battery allowed it to perform at 83% capacity over 900 cycles.
The researchers say this is the best reported performance for a sodium-ion battery with an antimony-based anode material. They aim to commercialise their technology.