New Research into Silicon anode Lithium Batteries could double the life of lithium batteries and increase power capability.

Adding graphene girders to silicon electrodes could double the life of lithium batteries

New research led by WMG, at the University of Warwick has found an effective approach to replacing graphite in the anodes of lithium-ion batteries using silicon, by reinforcing the anode's structure with graphene girders. This could more than double the life of rechargeable lithium-ion based batteries and also increase the capacity delivered by those batteries.

From article, (New research led by WMG, at the University of Warwick has found an effective approach to replacing graphite in the anodes of lithium-ion batteries using silicon, by reinforcing the anode's structure with graphene girders. This could more than double the life of rechargeable lithium-ion based batteries and also increase the capacity delivered by those batteries.

research, led by Dr Melanie Loveridge in WMG at the University of Warwick, has discovered, and tested, a new anode mixture of silicon and a form of chemically modified graphene which could resolve these issues and create viable silicon anode lithium-ion batteries. Such an approach could be practically manufactured on an industrial scale and without the need to resort to nano sizing of silicon and its associated problems. The new research has just been published on Tuesday 23rd January 2018) in Scientific Reports in a paper entitled Phase-related Impedance Studies on Silicon-Few Layer Graphene (FLG) Composite Electrode Systems.

Graphene is of course a single, one atom thick layer of the mineral graphite (an allotrope of carbon). However, it also possible to separate and manipulate a few connected layers of graphene giving a material 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 .

Dr Melanie Loveridge, who led the research and is a Senior Research Fellow in WMG at the University of Warwick 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 elasticity 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."

"More importantly, these FLG flakes can also prove very effective at preserving the degree of separation between the silicon particles. Each battery charge cycle increases the chance that silicon particles become electrochemically welded to each other. This increased agglomeration increasingly reduces and restricts the electrolyte access to all the particles in the battery and impedes effective diffusion of lithium ions, which of course degrades the battery's life and power output. The presence of FLG in the mixture tested by the WMG University of Warwick led researchers to hypothesize that this phenomenon is highly effective in mitigating electrochemical silicon fusion. This has been supported by systematic investigations"

The WMG research team have already begun further work on this technological advance which will include further study and research as part of the graphene spearhead two year project led by Varta Micro-innovations, WMG at the University of Warwick is a partner along with Cambridge University, CIC, Lithops and IIT (Italian Institute of Technology). The main goal of that project is to advance in pre-industrial production of silicon/graphene composites and their subsequent processing into lithium-ion batteries for high-energy and high-power applications. As part of that project WMG at Warwick will be optimising the electrode research, scale up and pouch cell manufacture of the optimised Li-ion batteries.)

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