Ultralight and self-extinguishing Lithium-ion batteries

Researchers from SLAC National Accelerator Laboratory have proposed a new technology to boost efficiency and make fire retardant batteries .

lithium ion batteries
Due to its rechargeability, lithium-ion batteries find immense applications in electrical vehicle’s military purposes and aerospace applications.

In this modern era of technological advancement power generation is not the only problem we are facing but dealing with the storage of this power is too of major concern. Lithium-ion batteries have shown promising results as they offer higher energy density and are lighter as well when compared to conventional rechargeable batteries.

There has been a lot of talk about replacing the solid current collector with the fabricated current collectors. Researchers from SLAC National Accelerator Laboratory have tried reducing the weight of the charge collector and found the energy density changing from 16% to 20%.

What is Energy density?

Energy density is the measure of energy stored in the given mass of a substance or a system. A battery with a higher energy density will store higher energy in a smaller mass. Batteries with higher energy density find application in the electric vehicle, laptops, and many other electrical appliances.

energy density of Lithium-ion batteries
Energy Density of Various Cells
  • Gravimetric energy density(Wh/kg)- gravimetric analysis is done when the mass of the battery is a major concern.
  • Volumetric energy density(Wh/m3)- volumetric analysis is a quantitative chemical analysis in which volume is an important factor to be considered

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Reduction in the weight of the current collector

A battery has two current collectors which make up the 15%-50% weight of the battery.

weight distribution of lithium ion battery

Researchers have successfully reduced this weight and claim to achieve an energy density of 16-26% with an 80% reduction in the weight, which is a good development as in recent years we achieved an average of 3%.

reduction in weight of lithium ion battery

They made the current collector more porous and thinner. Producing lighter batteries have numerous advantages. The electric vehicles with lighter batteries will not have to carry heavier loads and they can go the longer distance in a single charge.

This modification to the current collector has its disadvantages as the thin current collector leads to a fragile battery and more electrolyte is needed which raises the cost of the battery.

To overcome these problem fire retardants were used as an option for reducing the fire. The fire retardant may be a good option but cannot be added in a large quantity as it increases the density of the electrolyte which affects the mobility of lithium-ion.

Polymer foil sandwich

Cui, Ye, and graduate student Yayuan Liu(from SLAC National Accelerator Laboratory ) developed and designed a lightweight polymer-based current collector. They used polyimide, which resists fire.

Polyimide is a polymer of imide monomer having high heat resistant properties and find application in high-temperature fuel cells and various other roles.

Triphenyl phosphate, or TPP – was embedded in the polymer which was coated on both the surfaces of the ultra-thin layer of copper. Apart from working as a normal current collector copper with polymer coated with TPP acts as a fire retardant.

Flammability test

Researchers claimed the results were promising when they exposed the new flame-retardant batteries to fire along with the pre-existing batteries.

During their experiment with the battery, the normal battery kept burning till all of its electrolyte was not finished.

Very interesting result was achieved by the burning of fire-retardant batteries, Ye said the battery never really caught fire, and even there was fire it went down in seconds. Even on re-lighting, it did not give any flares

Advantages of lighter and flame-retardant batteries

  • Lighter batteries reduce the cost of transportation
  • Such batteries are good for powering EV
  • Low risk of fire
  • Reducing the use of copper and replacing a portion of it with polymers will reduce the cost of battery manufacturing.
Abhinav

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