Marie-Pierre Bichat

Electrochemical Reactivity of Cu3 P with Lithium

Copper phosphide, Cu 3 P, has been synthesized using a solvothermal route. The electrochemical reaction of this binary phosphide with lithium has been studied to describe the insertion/extraction mechanism. The discharge of the half-cell Cu 3 P/Li up to 0.1 V proceeds by lithium insertion into a Cu 3 P hexagonal structure and then by two successive biphasing processes involving the formation of LiCu 2 P and Li 2 CuP, respectively. Simultaneously, copper metal is extruded from the matrix. During the charge the reversible processes are observed. After 15 cycles a 400 mAh g -1 specific capacity is retained.

Anode materials for lithium ion batteries in the Li-Zn-P system

This paper presents an exhaustive study of the Li-Zn-P system through the synthesis and electrochemical characterisation of several binary and ternary phases: Li9ZnP4, LiZnP, Zn3P2 (α and β), ZnP2 (α and β), LiZn, and LiZn4. Three synthetic routes have been used to prepare these materials: ceramic synthesis and ball milling without and with annealing. Li-Zn-P system phases have been evaluated through X-ray diffraction and electrochemical reactivity towards lithium. Exhibiting high specific capacities at potentials close to 0.7 V vs. Li+/Li, some of these materials are promising as negative electrode materials for lithium ion battery.

Ball milling synthesis of LixTiP4: Improvement of the electrochemical performances

While promising performance as a negative electrode in Li-ion batteries, with flat voltage profiles at about 1 V and large specific capacities, today’s drawback with LixTiP4 materials is the difficulty encountered in preparing single-phase powders. To alleviate this issue, new synthetic routes have been investigated and we present here our results obtained by ball milling (BM) syntheses. Despite the poor crystallinity of the as prepared BM powders demonstrated by both X-rays and electron diffractions, preliminary electrochemical tests have shown a dramatic improvement of the specific capacity and charging-discharging rate confirming the advantages of BM synthesis over the high temperature route. To divert any amorphous phases contamination by amorphous phases contamination, BM samples were annealed at 500 °C and 900 °C. Nicely crystallized samples devoid of any impurities are obtained. We also detail in this paper the improvement in cyclability of these annealed BM LixTiP4 electrode materials.

Progress in the lithium insertion mechanism in Cu3P

Copper phosphide, Cu3P has been synthesized using a ceramic route, and its electrochemical behaviour versus lithium has been studied studied galvanostatic and potentiodynamic measurements and in situ X-ray diffraction analysis. The insertion/extraction mechanism proceeds with the formation of at least three different LixCu3−xP (x=1, 2, 3) phases. The electrochemical behaviour of Cu3P samples obtained from ceramic and solvothermal syntheses are compared to further understanding of the complex redox mechanism occurring during insertion/extraction. First-principle electronic structure calculations show that discharge probably begins with the formation of a solid solution LixCu3−yP (x<0.5).

A method for the fast estimation of a battery entropy-variation high-resolution curve – Application on a commercial LiFePO4/graphite cell

Abstract The entropy-variation of a battery is responsible for heat generation or consumption during operation and its prior measurement is mandatory for developing a thermal model. It is generally done through the potentiometric method which is considered as a reference. However, it requires several days or weeks to get a look-up table with a 5 or 10% SoC (State of Charge) resolution. In this study, a calorimetric method based on the inversion of a thermal model is proposed for the fast estimation of a nearly continuous curve of entropy-variation. This is achieved by separating the heats produced while charging and discharging the battery. The entropy-variation is then deduced from the extracted entropic heat. The proposed method is validated by comparing the results obtained with several current rates to measurements made with the potentiometric method.