New research led by the Warwick Manufacturing Group (WMG) at the University of Warwick has found an effective approach to replacing graphite in the anodes of lithium-ion batteries using silicon.
The research has found that reinforcing the anode’s structure with graphene girders could more than double the life of researchable lithium-ion based batteries by greatly extending the operating lifetime of the electrode. This will also increase the capacity of the batteries.
Graphite has been the default choice of active material for anodes in lithium-ion batteries since their launch. However, researchers and manufacturers have sought a way to replace graphite with silicon. The issues that surround silicon is that it has several performance issues that continue to limit its commercial exploitation.
Dr Melanie Loveridge at the University of Warwick’s WMG, has discovered, and tested, a new anode mixture of silicon and a form of chemically modified graphene which could resolve any issues previously posed and create viable silicon anode lithium-ion batteries.
This approach could be practically manufactured on an industrial scale, without any problems surrounding the nano-sizing of silicon.
Graphene is a single, one atom thick layer of mineral graphite. However, it is possible to separate and manipulate a few connected layers of graphene giving a material that researchers refer to as ‘few-layer graphene’ (FLG).
Previous research has tested the use of FLG with nano-sized silicon, but this new study has found that FLG can also dramatically improve the performance of larger micron-sized silicon particles when used in an anode. So much so that this mixture could significantly extend the life of lithium-ion batteries and also offer increased power capability.
The researchers created anodes that were a mixture of 60% micro silicon particles, 16% FLG, 14% Sodium/Polyacrylic acid, and 10% carbon additives, and then examined the performance (and the changes in structure of the material) over a 100 charge-discharge cycles.
Loveridge said: “The flakes of FLG were mixed throughout the anode and acted like a set of strong, but relatively elastic, girders. These flakes of FLG increased the resilience and tensile properties of the material greatly reducing the damage caused by the physical expansion of the silicon during lithiation. The graphene enhances the long range electrical conductivity of the anode and maintains a low resistance in a structurally stable composite.”