High performance electrodes for Li-ion battery

Patent filing number: 613/KOL/2014

Technology title: Porous nanostructured tin-animony-copper intermetallic electrodes as anode material for lithium ion batteries

1.    A brief description of the technology

The technology is capable of fabricating Tin-Antimony- Copper based open-pore three dimensional nanostructure anodes for lithium ion batteries, which display high discharge capacity as well as good cyclability. The fabrication was carried out through electrodeposition route and devoid of any post-plating treatment except vacuum drying. The developed anode did not contain any binder or additive which take up lithium and add to capacity.

2.    Commercial aspects of the technology & Industries benefiting from it

Electronics industries are heavily dependent on high capacity batteries.Various automobile companies are looking forward to launch electric vehicles to conserve fossil fuels. However they are stuck with performance of the battery especially the specific capacity. This technology has come up with a cheap fabrication process to increase battery capacity and will definitely be in the eye of those companies.This methodology can also be implemented to design and fabricate power sources for MEMS devices which are currently finding its use in diverse fields like biomedical instrumentation.

3.    Advantages of this technology over the already existing methods

Currently, most commercial lithium - ion batteries use graphite as the anodic material and lithium mixed oxide (e.g. LiCoO₂) as the cathodic material. Graphite, though readily available at an economical price, has a low theoretical gravimetric capacity (372mAh/g). This, in turn, reduces the overall discharge capacity of the battery. Recently, tin has emerged as one of the novel materials which have the potential to replace carbonaceous anode materials as it has a very high theoretical capacity (993 mAh/g). It however suffers from the drawback of a very high volume change during the lithiation/delithiation process (about 300%). This high volumetric expansion can lead to the gradual detachment of the anodic material from the current collector as well as its pulverization which ultimately results in a poor cyclability performance of the battery.

Various efforts have been made in this direction to overcome this particular shortcoming of tin based anodes. Alloying or forming mixtures with other active metals, notably antimony, is one of the most tried methods. While antimony is an active element, it reacts with lithium at a potential different from tin and hence buffers the expansion of the latter when it reacts with lithium.

Various efforts have been made in this direction to overcome this particular shortcoming of tin based anodes. Alloying or forming mixtures with other active metals, notably antimony, is one of the most tried methods. While antimony is an active element, it reacts with lithium at a potential different from tin and hence buffers the expansion of the latter when it reacts with lithium.

4.    A summary of the technical details involved.

This method uses an aqueous solution of inorganic salts of tin, antimony and copper and does not consist of any kind of surfactant or detergent. Deposition was done at very high overvoltage to facilitate hydrogen evolution in order to obtain a porous structure. The anode material shows a consistent capacity over 1100mAh. This is possible because of the presence of intermetallics in the material and open-pore morphology.

          5.    Future prospects of the technology.

To further increase the electronic conductivity of the anode and hence improve the rate capability, we plan to incorporate carbon nanotubes or graphene into our alloy system. This methodology is expected to show a drastic increase in the power density of the anode. We further plan to use this system as the anode for a battery along with the cathode which has been developed by our collaborators and improve on the results which we will obtain.

Inventors: Prof. Siddhartha Das, Prof. Karabi Das, Mr. Abhinav Kumar, Mr. Srijan Sengupta, Mr. Arijit Mitra