Lithium Titanium Oxide (Li4Ti5O12/LTO) is a promising candidate for graphite anode replacement. With its characteristics as a “zero-strain insertion compound” material, Li4Ti5O12 is safer to use as an anode material to replace graphite. This information was conveyed by Slamet Priyono at the promotion session of the Department of Metallurgical and Materials Engineering, FTUI which was held on Tuesday (28/6). Slamet was awarded a Doctorate with Cum Laude predicate and is the 53rd Doctor who graduated from the Department of Metallurgical and Materials Engineering and the 452nd Doctorate at FTUI.
“This material does not contain toxic elements, its availability is abundant and the price is relatively cheap. However, there are still obstacles, namely its lower capacity than graphite, low electronic conductivity and low lithium ion diffusion coefficient, causing this material to have the ability to withstand high rate conditions during the charge-discharge process which is also low. The poor conductivity and diffusion are caused by the lack of electrons in the 3d orbitals of Ti,” said Slamet.
The anode fabrication of lithium titanate (Li4Ti5O12) with Al3+ ion doping, and carbon coating using the sol-gel method has been successfully carried out. Al3+ ion doping, carbon coating, and surface modification are synergistically used to overcome the shortcomings of Li4Ti5O12. The sol-gel method in an acidic environment is a simple technique and is able to produce materials of small and uniform size which is seen as the best way to perform synergistically.
Gradual increase in pH can increase the impurity phase (rutile) and trigger agglomeration of particles and close the porous structure on the surface. Increasing the pH also decreases the diffusion coefficient, the value of the specific capacity and the rate of capability. Doping does not affect the phase, crystal structure and morphology. Al3+ ion doping tends to decrease the specific capacity at low C-rate (0.1C), but the addition of 0.03 mol Al3+ ion can increase the capability at high C-rate (5C and 10C). Carbon coating on the surface of Li4Ti5O12 did not change the phase and crystal structure of Li4Ti5O12 significantly.
Super P carbon coats Li4Ti5O12 evenly so it has the best specific capacity. Super P is light, porous and purer so the sample has a capacity of 249 mAh/g. Meanwhile, the sugar carbon blocked the pores of the electrode surface and still contained -OH groups so that it had a negative effect on electrochemical performance with a specific capacity of 100 mAh/g. Surface modification with sugar carbon on Al3+ doped Li4Ti5O12 with pyrolysis is able to make the surface rough, but the modification reduces the specific capacity value.
The doctoral promotion session was led by the Chair of the Session, Prof. Dr. Heri Hermansyah, ST., M.Eng., IPU. with the Promoter, Prof. Dr. Ir. Akhmad Herman Yuwono, M.Phil.Eng. and Co-Promoter, Dr. Wahyu Bambang Widayatno. The Examiner Team consists of Dr. Deni Ferdian, S.T., M.Sc., Drs. Nofrijon Sofyan, M.Sc., Ph.D, Dr. Ir. Bambang Priyono, MT, Prof. Dr. Ir. Anne Zulfia Syahrial, M.Sc., and Prof. Dr. Rike Yudianti.
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Public Communication Bureau
Faculty of Engineering, Universitas Indonesia