Thinner & Lighter Li-Ion Batteries

Researchers have found a new technique as a one step closer to create smaller and lighter batteries while storing the same amount of energy as compared to incumbent batteries.



Today lithium-ion batteries use graphite as one of the electrode. Graphite is a stable electrode but it can only store limited amount of energy/volume and energy/mass.

Germanium Anode

Germanium is one of the promising anodes for next-generation lithium-ion batteries. In theory, when storing the same amount of energy, graphite is 3.7 times heavier and 8.9 times bulkier than germanium. Thus, replacing graphite with germanium is a good idea.



However, germanium anode has problems of delamination, fracture and rupture during the battery operation, causing loss of electrical contact and decrease in battery performance after few cycles of charge and discharge.

A new technique of annealing post-treatment addressed the adhesion improvement of germanium film to its substrate. It prevented the delamination of thick germanium film which resulted in stable electrical contact and cycle life for up to 100 cycles.



The findings, published at Nano Energy (impact factor: 10.211), could have possible application in everyday life: 1) the development of thinner and lighter mobile phone or 2) mobile phone that can be charged twice a week instead of once a day.



However, the study is limited to the anode. Lithium-ion batteries have two electrodes of anode and cathode. Researchers need to develop better cathode to achieve a full impact to the world.

Motivation

I have three reasons to write this article: 1) to bridge the "research world" and the "layman world", 2) to disseminate our research results to reach wider audiences, and 3) to encourage fellow researchers to follow-up our works. If you like this post, please share it to your network. Thank you!

Further reading

Title: Influences of annealing on lithium-ion storage performance of thick germanium film anodes



Author: Rahmat Agung Susantyoko ‡, Xinghui Wang ‡, Leimeng Sun, Wardhana Sasangka, Eugene Fitzgerald and Qing Zhang*



Abstract: A high performance germanium (Ge) based anode is achieved through an appropriate air annealing post-treatment. Annealed Ge is fabricated by sputtering of Ge onto a stainless steel (SS) current collector and then annealed in air. It shows high specific and volumetric capacities of 1186 mA h g−1 and 5887.4 mA h cm−3, respectively, at the rate of 812 mA g−1 up to 50 cycles. These specific and volumetric capacities are approximately a factor of 20 higher than those from as-deposited Ge on the SS substrate. In addition, the annealed Ge has a higher initial Coulombic efficiency of 90.8% than the as-deposited Ge of 81%. The improved performance of the annealed Ge can be attributed to the enhanced adhesion of annealed Ge film to SS substrate through interdiffusion at the SS/Ge interface due to the annealing post-treatment.



‡These authors contributed equally to this work.



Link: http://dx.doi.org/10.1016/j.nanoen.2015.01.024

About me

Rahmat Agung Susantyoko received his B.Eng. from School of Materials Science and Engineering at Nanyang Technological University in 2008. He completed his M.Eng. in Materials Science and Engineering from Massachusetts Institute of Technology in 2009. Rahmat conferred a Ph.D. degree in Advanced Materials for Micro- and Nano-Systems at Nanyang Technological University in January 2015. Rahmat's research interests include but not limited to the fabrication and characterization of conversion- and alloying-based anodes for Li-ion battery: NiO, Si and Ge anodes.