Adding Graphene To Silicon Electrodes Double Lithium Batteries Life

New research led by WMG (academic department), at the University of Warwick (UK) 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 by greatly extending the operating lifetime of the electrode, and also increase the capacity delivered by those batteries.

Graphite has been the default choice of active material for anodes in lithium—ion batteries since their original launch by Sony but researchers and manufacturers have long sought a way to replace graphite with silicon, as it is an abundantly available element with ten times the gravimetric energy density of graphite. Unfortunately, silicon has several other performance issues that continue to limit its commercial exploitation.

Due to its volume expansion upon lithiation silicon particles can electrochemically agglomerate in ways that impede further charge-discharge efficiency over time. Silicon is also not intrinsically elastic enough to cope with the strain of lithiation when it is repeatedly charged, leading to cracking, pulverisation and rapid physical degradation of the anode’s composite microstructure. This contributes significantly to capacity fade, along with degradation events that occur on the counter electrode – the cathode. To use the mobile phones as an example, this is why we have to charge our phones for a longer and longer time, and it is also why they don’t hold their charge for as long as when they are new.

However new 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 been published in Nature Scientific Reports.


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