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Since the first demonstration of the lithium intercalation properties in lithium iron phosphate (LiFePO4) the interest for the material as a cathode for lithium-ion batteries has progressively increased. LiFePO4 represents a valid candidate to build large size batteries for powering electric vehicles or for realizing dispersed electrical power sources. Not only are the precursors relatively inexpensive, but iron is also less toxic compared to other materials used in lithium-ion technology such as cobalt, nickel, or manganese. In addition, the operating voltage of the LiFePO4 electrode (about 3.4 V vs. Li) is ideal to maximize energy while minimizing side reactions due to electrolyte decomposition. However, these positive aspects are counteracted by the low electronic conductivity of the material, resulting in considerable ohmic drop within the electrode. In addition, it has been noted that LiFePO4 displays limited high-rate capability, with considerable loss in utilization with increased current, suggesting lithium-ion transport limitations. Several methods such as doping, grain size reduction, and carbon coating have been proposed to improve the electrochemical properties of LiFePO4. In this chapter the chemical-physical characteristics of cathode materials for lithium-ion batteries are described and the main methods used to enhance the electrochemical performance of LiFePO4 are reported.

The surface engineering and the optimization of particle morphology have enhanced the LiFePO4 electrochemical performance, making this cathode material one of the most promising candidates to replace lithiated metal oxides in lithium-ion batteries. Many authors have attempted to improve the electrochemical performance of LiFePO4 by coating the surface with conducting particles (N. Ravet, J.B. Goodenough, S. Besner et al., Improved iron based cathode material. In Proceeding of 196th ECS Meeting, Hawaii, 17–22 Oct, 1999), or co-synthesizing the compound with conductive additives (Huang et al., Electrochem. Solid St. 4:A170–A172, 2001; Prosini et al., Electrochim. Acta 46:3517–3523, 2001). In both cases the conductive particles interfered with the grain coalescence determining the reduction of the grain size. Both particle size minimization and intimate carbon contact were claimed to be necessary to optimize the electrochemical performance. In this chapter we stress this concept reporting on a new reproducible synthetic route to prepare nano-particle LiFePO4/C composites, in which the phosphorus, iron and carbon atoms all originate from the same precursor. LiFePO4/C composites were prepared from thermal decomposition of Fe(II)organo-phosphonates Fe[(RPO3)(H2O)] (R = methyl or phenyl group) in presence of Li2CO3 at high temperature and under inert atmosphere (Bauer et al., Electrochem. Solid St. 7:A85–A87, 2004). The compounds were characterized by chemical analysis, TGA, DSC, X-ray powder diffraction, and SEM technique. Electrodes were fabricated for the electrochemical characterization. The cathode material obtained from Fe[C6H5PO3(H2O)] showed a specific energy evaluated at C/10 rate of about 550 Wh kg?1. The specific power calculated at 30C rate was in excess at 14000 W kg?1, while the specific energy was about 28% of the theoretical one. No capacity fading was observed upon cycling.

In the previous chapter it was shown that amorphous FePO4 was obtained by following a solution-based approach (Prosini et al., J. Electrochem. Soc. 149:A886–A890, 2002). Crystallization of the amorphous material at 650°C leads to the formation of hexagonal FePO4. The phase resulted was not isostructural with FePO4 (heterosite) formed on lithium extraction from LiFePO4 (triphylite) with ordered olivine-type structure. The amorphous FePO4 was chemically lithiated using lithium iodide as the reducing agent. In such a way it was possible to obtain a new phase, amorphous LiFePO4 , which was not previously accessible. In this chapter nano-crystalline LiFePO4 with ordered olivine-type structure was obtained by heating the amorphous nano-sized LiFePO4 precursor. The so-obtained material was characterized by chemical analysis, TG, DTA, X-ray powder diffraction, SEM, and BET. The material was tested as a cathode for lithium-ion batteries (Prosini, J. Electrochem. Soc. 149:A886–A890, 2002). Nano-crystalline LiFePO4 showed very good electrochemical performance delivering the full theoretical capacity (170 Ah kg?1) when cycled at 17 A kg?1 at room temperature. A capacity fade of about 0.25 % per cycle affected the material upon cycling.

Wet chemical methods, such as the hydrothermal, template, and precipitation process provide effective-cost preparation techniques, especially if compared to “high-temperature” methods (Dominko et al., J Power Sour. 153, 274–280, 2006; Yang et al., Electrochem. Commun. 3, 505–508, 2001; Zhang et al., Funct. Mater Lett. 3, 177–180, 2010; Palomares et al., J. Power Sour. 171, 879–885, 2007). Liquid-phase synthesis has the advantage to be carried out at low temperatures (low energy), to be flexible and controllable and to give materials with homogeneous nano-particle structures. An obvious disadvantage of the synthesis in liquid phase is that the so-obtained materials show low density. In this chapter a sol–gel route to prepare iron (II) phosphate is reported. Synthetic vivianite (Fe3(PO4)3×nH2O) (Scaccia et al., Thermochim. Acta. 397, 135–141, 2003) was obtained by adding phosphate ions to a solution of Fe2+. It is well known that natural ferrous phosphate (vivianite) rapidly oxidizes on exposure to air, passing through deepening shades of blue to finally become brown beraunite (3Fe2O3•2P2O5•10H2O). The vivianite obtained by the sol–gel route was dried in air at 100°C. The so-obtained material was characterized by TG/DTG/DTA, XRD, SEM and Mossbauer spectroscopy and its electrochemical behavior as a cathode in a non-aqueous lithium cell was evaluated (Prosini et al., J. Electrochem. Soc. 148, A1125–A1129, 2001) .

Amorphous 3Fe 2 O 3 .2P 2 O 5 .10H 2 O was prepared by oxidation of iron(II) phosphate, obtained by spontaneous precipitation from iron(II) and phosphate aqueous solutions, by heating in air at 100°C. The material was characterized by thermal analysis, Mossbauer spectroscopy, X-ray powder diffraction, and scanning electron micrograph analysis. The material, tested as cathode in a nonaqueous lithium cell, exhibited a specific capacity of about 140 mAh g -1 at a current density of 25 mA g -1 . The utilization was reduced to about 76% by a tenfold increase of the discharge current. It showed an excellent cyclability. More than 1000 cycles were performed at about 50% of depth of discharge, with a capacity fade lower than 0.025%.

Nanocrystalline LiFePO 4 was obtained by heating amorphous nanosized LiFePO 4 . The amorphous material was obtained by lithiation of FePO 4 synthesized by spontaneous precipitation from equimolar aqueous solutions of Fe(NH 4 ) 2 (SO 4 ) 2 .6H 2 O and NH 4 H 2 PO 4. using hydrogen peroxide as the oxidizing agent. The materials were characterized by chemical analysis, thermogravimetric and differential thermal analysis, X-ray powder diffraction, and scanning electron microscopy. The Brunauer- Emmett-Teller method was used to evaluate the specific surface area. Nanocrystalline LiFePO 4 showed very good electrochemical performance delivering about the full theoretical capacity (170 Ah kg -1 ) when cycled at the C/10 rate. A capacity fade of about 0.25% per cycle affected the material upon cycling.

The hydrogen storage properties of doped and undoped NaAlH4 samples are studied after mixing them with different percentages of high surface carbon. Manually mixed samples are compared with ball milled ones; it was found that manual mixing was a simple and effective way to dope NaAlH4. A morphological and micro-structural analysis has been carried out in order to understand the effect of carbon. Carbon added samples show a marked enhancement of hydrogen desorption rate. The desorption temperature and the total hydrogen content remain almost unchanged for undoped sample. The desorption temperatures of Ti-doped samples increase with carbon content. (C) 2006 Elsevier B.V. All rights reserved.

A sustainable energy economy will be demanding primary energy sources, preferably renewable and mainly domestically available, using energy carriers, such as hydrogen and electricity, able to solve environmental problems and to assure adequate energy security. Instrumental to such goals will be the research and development of storage systems with performance characteristics compatible with major application requirements. Lithium or nickel are replacing lead in batteries, in order to better meet the extremely varying technical and economical requirements in fast growing conventional and new applications. Moreover, few technologies now permit to store hydrogen by modifying its physical state in gaseous or liquid form. The variety of hydrogen needs in the energy systems and in the vehicular sector is justifying the effort on solid state (metal hydrides and carbon nanostructures) or chemical systems (chemical hydrides). In this overview, emphasis is given to the major achievements in the field of electrical energy and hydrogen storage, in relation to the technological goals, which have been proposed in the major public research and collaborative programs throughout the world.

LiFePO 4 /C composites were prepared from thermal decomposition of Fe(II) organophosphonates Fe[(RPO 3 )(H 2 O)] (R = methyl or phenyl group) in the presence of Li 2 CO 3 at high temperature and under inert atmosphere. The compounds were characterized by chemical analysis, thermogravimetric analysis and differential scanning colorimetry, X-ray powder diffraction, and scanning electron microscopy. Electrodes were fabricated for the electrochemical characterization. The cathode material obtained from Fe[C 6 H 5 PO 3 (H 2 O)] showed a specific energy evaluated at C/10 rate of about 550 Wh kg - 1 . The specific power calculated at 30C rate in excess at 14,000 W kg - 1 , while the specific energy was about 28% of the theoretical one. No capacity fading was observed upon cycling.

Amorphous iron(III) phosphate was synthesized by spontaneous precipitation from equimolar aqueous solutions of and using hydrogen peroxide as the oxidizing agent. The material was characterized by chemical analysis, thermogravimetrical analysis, differential thermoanalysis, X-ray powder diffraction, and scanning electron microscopy. The material was tested as a cathode in nonaqueous lithium cells. Galvanostatic intermittent titration technique was used to follow the lithium intercalation process. The effect of firing on the specific capacity was also tested. The material fired at 400°C showed the best electrochemical performance, delivering about 0.108 Ah g−1 when cycled at C/10 rate. The capacity fade upon cycling was found as low as 0.075% per cycle. © 2002 The Electrochemical Society. All rights reserved.

LiFePO4 was synthesized in the presence of high-surface area carbon-black. The carbon was added to the precursors before the formation of the crystalline phase. SEM micrographs confirmed that the addition of the fine carbon powder reduces the LiFePO4 grain size. The carbon is uniformly dispersed between the grains, ensuring a good electronic contact. Electrochemical tests showed that the material obtained by adding 10 wt. % of carbon gives enhanced performance in terms of improved practical capacity and charge/discharge rate. The specific capacity was seen to increase on increasing temperatures. The full capacity (170 mAh g-1) was delivered when discharging the cell at 80°C and C/10 rate. The cyclability of the material was tested at room temperature and C/2 rate. The cell was cycled for over 230 cycles with an average specific capacity of about 95 mAh g-1.

Nuclear hydrogen production is a technically feasible and economically viable option for addressing future energy needs. Several projects have been started on the co-generation of hydrogen and electricity from nuclear energy. In this report, the nickel sulphur iodine (NIS) cycle, a thermochemical water splitting cycle originally developed in ENEA for solar hydrogen production was studied to be coupled with a new generation nuclear reactor for massive hydrogen production.

To evaluate the possibility to use molten carbonate fuel cell technology for high temperature electrolysis, the factors affecting the electrode reactions have been examined by surveying the published literature. The literature results showed that H2, CO2 and CO evolved as cathode off-gases and O2 as anode gas. At low polarisation, the discharge of oxide ions to O2 was the only anodic process; increasing polarisation and current densities, the discharge of carbonate ions contributed to the anodic reaction and CO2 was concurrently produced at the anode. Molten Li2CO3 at 850°C–900°C readily absorbed the produced CO2 (the CO2 concentration in the anode compartment was lower than 0.5%). In this condition, titanium cathode enhanced CO production. The co-production of CO represents a serious disadvantage to power a polymer electrolyte membrane fuel cell. On the other hand, the production of syngas could offer attractive applications such as synfuel production and carbon dioxide regeneration.

To explain the lithium insertion/deinsertion in LiFePO4 Padhi et al. (J. Electrochem. Soc. 144:1188–1194, 1997) proposed that the lithium motion proceeds from the surface of the particle moving inward through a two-phase interface (shrinking core model). During this process lithium ions and electrons have to move out through the newly formed FePO4 phase. Andersson et al. in addition to the “radial model” (Andersson et al., Electrochem. Solid St. 3:66–68, 2000) proposed a “mosaic model” (Andersson and Thomas, Electrochem. Solid St. 3:66–68, 2001) that invokes a mosaic character within each particle. The idea is that lithium insertion/deinsertion can occur in many sites within a given particle. More recently Newman studied the lithium insertion in LiFePO4 using the shrinking core model (Srinivasan and Newman, J. Electrochem. Soc. 151:A1517–A1529, 2004). Upon charge a Li-rich core is covered by a Li-deficient shell while the Li-rich shell is formed on the Li-deficient core upon discharge. Delmas et al. (Nat. Mater. 7:665–671, 2008) proposed a “domino-cascade model” in which the existence of structural constraints, occurring just at the reaction interface, lead to the minimization of the elastic energy thus enhancing the deintercalation (intercalation) process. To date, the lithium/insertion reaction mechanism in LiFePO4 is not completely understood. The flat discharge plateau exhibited by two-phase systems makes it difficult to use the voltage to predict the state of charge of the material. The purpose of the study is to propose a model to correlate the voltage profiles to the physical and chemical processes that give rise to the discharge curves. The proposed model is based on chemical and physical processes in terms of crystallographic data and electronic/ionic diffusion and physical representation of lithium insertion/deinsertion in the material. LiFePO4 is isostructural with the delithiated form, FePO4. The cell parameters change by removing lithium from the structure, the a and b parameters decrease upon delithiation while the c parameter increases. As a consequence the cell volume decreases from 291.33 to 273.36 A3 (Padhi et al., J. Electrochem. Soc. 144:1188–1194, 1997). Starting from the claim that by growing from the center the delithiated phase can reduce the stress originating from volume contraction, a general equation describing the voltage profile as a function of the intercalation degree was developed for C/10 discharge rate (Prosini, J. Electrochem. Soc. 152:A1925–A1929, 2005). The voltage profile of LiFePO4 was described as the sum of three individual contributions: (i) the rapid segregation of lithium on the grain surface during the first stage of the intercalation process, (ii) the flat voltage region characteristic of a two-phase system, (iii) the decay of the voltage at the end of the intercalation process. The equation was successfully used to describe the voltage profile of LiFePO4 for increasing discharge rates up to 10C. The proposed equation could be used to evaluate the state of charge of the material by fitting the discharge curve with an appropriate algorithm. Fongy et al. (J. Electrochem. Soc. 157:A885–A891, 2010) used the proposed model to extract from the LiFePO4 discharge curves two parameters. The parameters were used to determine the optimal electrode engineering and to interpret the origins of the electrode performance limitations.

In this paper the electrochemical characterization of a composite electrode based on β-lithium nitride (β-Li 3 N), iron, and synthetic graphite is reported. β-Li 3 N, the high pressure form of Li 3 N, was obtained by ballmilling a mixture of Li 3 N and iron metal. The electrochemical behavior of β-Li 3 N/Fe mixtures and pure graphite electrodes was also studied. It was found that lithium can be extracted from the β-Li 3 N in the presence of iron at a flat potential of 1.1 V vs. Li. A specific capacity as high as 612 mAh g -1 was recorded during the first lithium extraction. A drastic reduction of the capacity was observed on further cycling. The β-Li 3 N was used as a source of lithium for the lithiation of graphite composite electrodes. A composite electrode was prepared assuming that all the lithium extracted from β-Li 3 N was reinserted into the graphite during cycling. Upon cycling, a progressive decrease in the β-Li 3 N contribution to the electrode capacity and, concurrently, an increase in the graphite contribution were observed and after 320 cycles lithium was intercalated exclusively into the graphite. The electrode cycled for 500 cycles with a specific capacity of 315 mAh g (based on the graphite weight) without any capacity loss.

Nanocrystalline LiFePO 4 was obtained by heating amorphous nanosized LiFePO 4 . The amorphous material was obtained by lithiation of FePO 4 synthesized by spontaneous precipitation from equimolar aqueous solutions of Fe(NH 4 ) 2 (SO 4 ) 2 .6H 2 O and NH 4 H 2 PO 4. using hydrogen peroxide as the oxidizing agent. The materials were characterized by chemical analysis, thermogravimetric and differential thermal analysis, X-ray powder diffraction, and scanning electron microscopy. The Brunauer- Emmett-Teller method was used to evaluate the specific surface area. Nanocrystalline LiFePO 4 showed very good electrochemical performance delivering about the full theoretical capacity (170 Ah kg -1 ) when cycled at the C/10 rate. A capacity fade of about 0.25% per cycle affected the material upon cycling.

O was prepared by oxidation of iron~II! phosphate, obtained by spontaneous precipitation fromiron~II! and phosphate aqueous solutions, by heating in air at 100°C. The material was characterized by thermal analysis,Mo¨ssbauer spectroscopy, X-ray powder diffraction, and scanning electron micrograph analysis. The material, tested as cathode ina nonaqueous lithium cell, exhibited a specific capacity of about 140 mAh g

This report describes the fabrication and characterization of polymer‐based composite cathode membranes intended for use in polymer‐electrolyte batteries operating at moderate temperatures (60–100°C). The present work is focused on the determination of morphological, thermal, mechanical, and electrical properties of PEO‐based composite cathodes. The work was developed within the Advanced Lithium Polymer Electrolyte project (ALPE), an Italian integrated project devoted to the realization of lithium polymer batteries for electric vehicle applications. © 2000 The Electrochemical Society. All rights reserved.

We have used a lithiated MnO 2 , Li 0 33 MnO 2 , with ordered alternating one-dimensional [1 × 2] and [1 × 1] channels as a cathode material in solid-state lithium/polymer cells. An optimized cell can operate at moderate temperatures (40-80°C). Li 0.33 MnO 2 delivers a rechargeable capacity of 160 mAh/g with a flat potential plateau at ca. 3.0 V vs. Li/Li + at the C/3 rate and 65°C, corresponding to a specific energy of 450 Wh/kg of the pure oxide. Cells show good rate capability and excellent cyclability when cycled between 2.7 and 3.5 V at 80% depth of discharge, whereas a capacity decline was observed when cycled between 2.0 and 3.5 V. Capacity fading upon cycling is believed to be due to the formation of a thin layer of spinel phase (transformation to Li 0.5 MnO 2 from Li 0.33 MnO 2 ) on the particle surfaces, as well as to increased cell resistance during charge/discharge cycling. The cell self-discharge at high temperature and the thermal stability of Li 0.33 MnO 2 in contact with the polymer electrolyte are also discussed.