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Wednesday, 18 September 2019
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Raw materials & technologies

Glue-like material improves lifetime of lithium-ion batteries

Thursday, 22 August 2013

Improving the lifetime of lithium-ion batteries up to 500 cycles? It’s possible, simply by using lithium sulfide, carbon particles and a glue-like material as the binder.

The glue acts as a binder between the carbon particles and the sulfide

Source: Chrionny / Fotolia

The glue acts as a binder between the carbon particles and the sulfide

Source: Chrionny / Fotolia

When it comes to improving the performance of lithium-ion batteries, no part should be overlooked – not even the glue that binds materials together in the cathode, researchers at SLAC National Accelerator Laboratory and Stanford University have found. Tweaking that material, which binds lithium sulfide and carbon particles together, created a cathode that lasted five times longer than earlier designs.

 

Glue-like material acts as a binder between carbon particles and sulfide

Cui's group was exploring how to create a better cathode by using lithium sulfide rather than sulfur. The lithium atoms it contains can provide the ions that shuttle between anode and cathode during the battery's charge/discharge cycle; this in turn means the battery's other electrode can be made from a non-lithium material, such as silicon. Unfortunately, lithium sulfide is also electrically insulating, which greatly reduces any battery's performance. To overcome this, electrically conducting carbon particles can be mixed with the sulfide; a glue-like material, the binder, holds it all together.

Long-lived battery reaches 500 cycles and more

 

The experimental battery using the new binder, known by the initials PVP, retained 94 % of its original energy-storage capacity after 100 charge/discharge cycles, compared with 72 % for cells using a conventionally used binder, known as PVDF. After 500 cycles, the PVP battery still had 69 % of its initial capacity.

 

Binder and lithium sulfide improve battery’s capacity

Cui said the improvement was due to PVP's much stronger affinity for lithium sulfide; together they formed a fine-grained lithium sulfide/carbon composite that made it easier for lithium ions to penetrate and reach all of the active material within the cathode. In contrast, the previous binder, PVDF, caused the composite to grow into large clumps, which hindered the lithium ions' penetration and ruined the battery within 100 cycles.

Aim: Extend the battery’s lifetime to more than 1000 cycles

Even the best batteries lose some energy-storage capacity with each charge/discharge cycle. Researchers aim to reduce such losses as much as possible. Further enhancements to the PVP/lithium sulfide cathode combination will be needed to extend its lifetime to more than 1,000 cycles, but Cui said he finds it encouraging that improving the usually overlooked binder material produced such dramatic benefits.

Please find further information here:

Chemical Science, 2013, 4, 3673-3677.

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