How To Extend The Charge-to-charge Life of Phones And Electric Cars By 40 %

The need to store energy for portable devices, vehicles and housing is ever increasing.The transformation from fossil fuels to renewable energy sources need to be hastened to decrease greenhouse gases and limit global warming. The utilization of wind and solar power requires effective storage system to ensure continuous energy supply as a part of smart grid. Li-ion batteries are considered to be the best route for many advanced storage applications related to the clean electricity due to their high energy density.

The latest lithium-ion batteries on the market are likely to extend the charge-to-charge life of phones and electric cars by as much as 40 percent. This leap forward, which comes after more than a decade of incremental improvements, is happening because developers replaced the battery’s graphite anode with one made from silicon. Research from Drexel University and Trinity College in Ireland now suggests that an even greater improvement could be in line if the silicon is fortified with a special type of material called MXene.

Regarding the present Li-ion batteries, one of the limiting factors in their performance is the anode material that most commonly is graphite. Silicon is a promising material for Li-ion battery anodes: By using silicon instead of graphite, the energy density of a battery cell ccould be increased by 30 %. To achieve this, several obstacles have to be overcome: First, silicon experiences a volume expansion of 300 % when lithiated. During discharging, the particles tend to fracture and lose contact. Secondly, the volume expansion prevents the formation of a stable electrode-electrolyte interface resulting in a continuous decomposition of the electrolyte. These two reasons are main causes for the limited use of silicon in commercial batteries.

The image shows PSi microparticles connected to each other with CNTs to improve the conductivity of the material

Both of the above mentioned problems with silicon material can be avoided by designing optimal porous structures of mesoporous silicon (PSi). Porosity of PSi needs to be high enough for the material to be able to withstand the volume expansion but also low enough so that the volumetric capacity/energy density is still better than for graphite anodes.


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