Tin is one of the most promising materials for sodium-ion battery negative anodes. Tin can store much larger amounts of sodium than hard carbon can, although tin’s rapid expansion shortens battery life. But Chinese scientists may be cracking the code with tin in sodium-ion chemistry, so do read on.
This discovery means that future sodium-ion batteries could hold more energy, without being larger or heavier. This advance could benefit electric vehicles and renewable energy storage installations. This step forward is part of an ongoing project to increase sodium-ion storage using tin, while still maintaining chemical stability.
What’s Wrong With Tin in Sodium-Ion Batteries?
Tin changes size dramatically as the battery charges and discharges. It expands as it absorbs sodium ions, and shrinks again when the sodium ions leave.
This repeated movement can crack tin over many charging cycles, reduce electrical contact and shorten battery life. These problems have thus far prevented widespread adoption of this otherwise promising material.
Researchers Exploring Ways to Sort Out Tin
Cracking the code to using tin in sodium-ion battery anodes, has not proven easy. One promising option involves combining tin with carbon and / or other materials, that provide strength and flexibility.
Another option is turning tin into tiny particles or porous structures, that are more able to absorb expansion. Protective coatings may also improve electrode durability.
A Fresh Discovery Could Make Tin Feasible
Researchers from Anhui Normal University in China, have developed a carbon-coated ‘superstructure’. This specially-engineered battery material combines zinc sulphide, tin disulphide, and tin oxide within a thin layer of carbon.
What Does This Do For Tin And Sodium-Ion?
The team at Anhui Normal University in China, may have cracked the code with tin in sodium-ion batteries, in terms of the following:
- The superstructure improved both electron transport and sodium-ion diffusion.
- The hollow carbon-coated architecture accommodated expansion during cycling.
- The prototype battery had a reversible capacity of 612 mAh after 100 cycles.
- It retained 471 milliampere-hours per gram after 400 charge-discharge cycles.
Steady On Before You Get Too Excited
This work is still at the research phase in a laboratory. Perhaps we should not read too much into the fact that Shenzhen BYD Lithium Battery Co. Ltd is keeping an eye on progress.
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