Russian Journal of Applied Chemistry, 2011, Vol. 84, No. 10, pp. 1744−1747.
Pleiades Publishing, Ltd., 2011.
Original Russian Text © K.S. Smirnov, N.A. Yashtulov, G.M. Kuz’micheva, V.A. Zhorin, 2011, published in Zhurnal Prikladnoi Khimii, 2011, Vol. 84, No. 10,
AND CORROSION PROTECTION OF METALS
Synthesis and Electrochemical Properties
of Lithium Iron Phosphate
K. S. Smirnov, N. A. Yashtulov, G. M. Kuz’micheva, and V. A. Zhorin
Moscow Institute of Power Engineering, Moscow, Russia
Received June 3, 2011
Abstract—Original method for synthesis of lithium iron phosphate was developed. The method includes two
stages: 1st, synthesis of iron phosphate from a mixture of ammonium dihydrophosphate and metal oxide; and 2nd,
synthesis of lithium iron phosphate by thermal lithiation of the product obtained in the 1st stage, with mechanical
activation of the precursor in the course of plastic deformation.
Recently, the demand for ﬁ lm-type lithium batteries
has increased, which is due both to the tendency toward
miniaturization of electronic boards and to the increased
requirements imposed by power consumers [1–4]. The
development of ﬁ lm batteries substantially expands the
opportunities of modern miniature devices, such as smart
cards, implanted medical devices, memory units, various
sensors, and converters. One of the main difﬁ culties in
creation of ﬁ lm batteries consists in development of
efﬁ cient cathode materials. Recently, much attention has
been given to inexpensive and nontoxic iron phosphates
, which have discharge
potentials of 3.4 and 2.8 V, respectively.
has a comparatively high theoretical capacity
(170 mA h g
), which can be nearly fully implemented in
practice. However, important disadvantages of LiFePO
are its low electronic and ionic conductivity, which
leads to a noticeable deterioration of electrochemical
characteristics at higher discharge current [1, 4].
Particular attention is being given to improvement of the
synthesis technology of LiFePO
, optimization of the
temperature of high-temperature synthesis, synthesis
in microwave ovens, mechanochemical synthesis, and
emulsion drying, which makes it possible to improve
parameters of electrodes based on this material [5–9].
The parameters are mostly improved because more
ﬁ nely dispersed powders are obtained.
is distinguished by a sufﬁ ciently
high conductivity. The practical capacity and cycling
ability of Li
are determined by its synthesis
conditions . The authors of  demonstrated
that, on being ground in a ball mill, Li
a capacity increased to 1.5–1.6 Li (120 mA h g
compared with 1.1 Li for the unground material.
Lithium iron phosphate (LFP) is presently
synthesized using expensive iron salts, which poses
certain problems in its mass production . Iron
is the least expensive and most readily
available reagent. An important advantage of Fe
that the product : reagent ratio is large (76.7%) and no
contaminating gases are formed .
In the methods known from the literature, synthesis
of lithium metal phosphates is a double-stage
thermal synthesis of ternary mixtures: ammonium
dihydrophosphate, metal oxide, and lithium compounds.
However, it has been found that its mechanism is rather
complicated and presumably includes several parallel
Therefore, the following two-stage process model
has been suggested: 1st, synthesis of metal phosphate
from a mixture of ammonium dihydrophosphate; and
2nd, synthesis of lithium metal phosphate by thermal
lithiation of the product obtained in the 1st stage [12,
It has been shown previously that the mechanical