Preparation and characterization of carbon foams–LiCoPO4 composites

Nanostructured LiMPO4(M = Fe, Mn, Co, Ni) – carbon composites as cathode materials for Li-ion battery

“…In fact, the degradation of the electrolyte on the cathode side may cause a limitation in mass transport on the cathode/electrolyte interface. Our experimental results and experience have shown that the influence of the electrolyte decomposition on the capacity fade of the LiCoPO 4 system can be considered minimal [5]. An additional factor to be considered can be the growth of secondary phases (particularly Co 2 P as confirmed by the XRD analysis) on the grain boundaries that could behave like "resistors" allowing the electron flow but adding a further potential on the surface that would inhibit the Li-ions transfer.…”

“…The XRD diffractogramm (Figure 3a) of a LiCoPO 4 /C-foam composite annealed at 730°C for 5 h, reveals the presence of the olivine-like structured LiCoPO 4 as single crystalline phase. At higher annealing times crystalline reflections, attributed to Li 4 P 2 O 7 as secondary phase, have been also detected [5]. The morphological investigation of the LiCoPO 4 /C-foam composites revealed the presence of layer which is not uniformly distributed on the surface of the foam ( Figure 3B).…”

“…The experimental procedures for the preparation and characterizations of the samples have been previously reported [3][4][5]. The samples in the LiMPO 4 system (M = Fe, Co, Ni) have been prepared by dissolving in water lithium acetate, iron sulfate (cobalt acetate, nickel acetate) as precursors (molar ratio 1:1) with citric acid (2 x mol [Fe, Co, Ni]), then adding phosphoric acid in the equimolar ratio with Li ions.…”

“…For the measurements, Swagelok-type cells were assembled in an argon-filled dry box with water and oxygen less than 5 ppm. In the cell, Li metal was used as anode, SelectiLyte LF30 as electrolyte [5] and Celgard®2500 as separator.…”

Effect of the Mg-substitution on the graphitic carbon foams—LiNi1−yMgyPO4 composites as possible cathodes materials for 5V applications

“…Indeed, both LiCoPO 4 and LiNiPO 4 have difficulties to de-intercalate Li + within the voltage stability window of the existing non-aqueous electrolytes. Anyway, efforts in improving the electrolyte have recently made it possible to explore the LiCoPO 4 compound [9][10][11] and LiCoPO 4 -carbon foams composites [12] above 5 V. The information available about the electrochemical performance of LiNiPO 4 is very limited due to the difficulty in obtaining a pure phase of lithium nickel phosphate [13,14]. Few studies [13][14][15][16] on this material have mostly shown that lithium nickel phosphate is not electrochemically active; no lithium can be subsequently intercalated if it is charged over 5.2 V. On the other hand, Wolfenstine [7] have reported the electrochemical activity of LiNiPO 4 powders prepared by solid state reaction under high purity argon gas with the addition of a carbon coating.…”