ISSN 1070-4272, Russian Journal of Applied Chemistry, 2015, Vol. 88, No. 5, pp. 898−899. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © A.A. Popovich, M.Yu. Maximov, A.M. Rumyantsev, P.A. Novikov, 2015, published in Zhurnal Prikladnoi Khimii, 2015, Vol. 88, No. 5,
Lithium cobaltate is among cathode materials widely
used in lithium-ion batteries [1, 2]. One of ways to
improve its stability is by deposition of passivating
coatings intended to preclude the gradual dissolution of
the cathode material because of the presence and gradual
formation of trace amounts of hydroﬂ uoric acid .
Aluminum oxide  is used as a material of protective
coatings deposited in various ways: by the sol-gel method,
by deposition from liquid and gas phases, etc.
The oxide can be deposited by the atomic-layer
deposition (ALD) method known in the Russian
literature as the molecular layering technique [5, 6].
The ALD is a self-controlled heterogeneous process.
In the general form, the method consists in successive
delivery of vapors of starting substances into the reaction
zone, which interact with the substrate surface to give
a monolayer of the compound in a single treatment
cycle. A multiple alternation of the reagent delivery
into the reactor with a substrate results in that the layer
of a substance grows, with its thickness determined by
the number of treatment cycles. Between the reagent
delivery pulses, the reactor is purged with an inert gas
to remove unreacted starting substances and gaseous
reaction products being formed.
Previously, experimental studies of the effect
of a passivating aluminum oxide coating on the
electrochemical properties of lithium cobaltate have been
carried out . The inﬂ uence exerted by the thickness
of the aluminum oxide coating deposited on powders
of the cathode material was examined and it was shown
that the cycling stability during 120 cycles increased by
40%. To assess the possibility of operation of ﬁ nished
electrode with a passivating coating under deep-autonomy
conditions, endurance tests during 1300 cycles were
performed in the present study.
Electrode samples were prepared from lithium
cobaltate LC08R (Shanghai Shanshan, China). To
preserve the electrical contact between the electrode
components , the coatings were deposited directly on
the resulting porous electrodes for lithium-ion batteries.
The active mass of the cathode, subsequently deposited
onto an aluminum foil to fabricate the electrodes under
study, was composed of 90 wt % LiCoO
, 5 wt % carbon
black (Timcal Super C65), and 5 wt % polyvinylidene
ﬂ uoride (Arkema Kynar 761A) in N-methylpyrrolidone.
Thin aluminum oxide ﬁ lms with various thicknesses
were deposited by using trimethylaluminum and distilled
water as starting reagents. The process was performed
on a Picosun R-150 atomic-layer deposition installation
Improvement of the Cycle Life of LiCoO
Used in Lithium-Ion Batteries
A. A. Popovich
, M. Yu. Maximov
, A. M. Rumyantsev
, and P. A. Novikov
Peter the Great Petersburg State Polytechnic University,
ul. Politekhnicheskaya 29, St. Petersburg, 195251 Russia
Ioffe Physical-Technical Institute, Russian Academy of Sciences,
ul. Politekhnicheskaya 26, St. Petersburg, 194021 Russia
Received October 14, 2014
Abstract—Effect of passivating aluminum oxide coatings of various thicknesses, formed by the atomic-layer
deposition method on porous lithium cobaltate electrodes, on the cycle life of lithium-ion batteries was studied.