Fabrice Coustier

Doped Vanadium Oxides as Host Materials for Lithium Intercalation

An improved cathodic material has been obtained by doping vanadium oxide hydrogel with silver. Silver-doped vanadium pentoxides with a silver molar fraction ranging from 0.01 to 1 were synthesized. With the successful doping, the electronic conductivity of V{sub 2}O{sub 5} was increased by 2 to 3 orders of magnitude. The electrochemical performance of the silver doped materials is very high, up to 4 moles of lithium per mole of silver-doped V{sub 2}O{sub 5} were found to be reversibly intercalated. In addition, the lithium diffusion coefficient is found to be high in the silver-doped material and with a smaller dependence on the lithium intercalation level. These enhancements resulted in high rates of insertion and delivered capacities.

Dip-coated silver-doped V2O5 xerogels as host materials for lithium intercalation

Abstract Vanadium pentoxide xerogels have shown high electrochemical performance in terms of energy content. The high specific energy and high intercalation capability make the materials promising for thin film lithium battery and electrochromic device applications. In order to enhance the rate capabilities of the host we increased the electronic conductivity by doping the V 2 O 5 xerogels with silver. Samples were prepared by mixing various amounts of silver powder with V 2 O 5 hydrogel. We were able to prepare silver-doped vanadium pentoxide dip-coated thin films with a molar ratio (Ag/V) ranging from 0.005 to 0.5 (Ag y V 2 O 3 with y = 0.01, 0.1 and 1). With the successful doping, the electronic conductivity of V 2 O 5 was increased by 2 to 3 orders of magnitude. The insertion capacity of the material was maintained and up to 4 moles of lithium per mole of silver-doped V 2 O 5 (XRG) were found to be reversibly intercalated.

A 400 mAh/g aerogel-like V2O5 cathode for rechargeable lithium batteries

A highly amorphous V 2 O 5 material composed of a highly interconnected, very thin solid phase has been prepared via a combined sol-gel and solvent exchange procedure. Electrochemical tests performed on composite cathodes based on the material demonstrated its very high lithium insertion capacity (up to 410 mAh/g or 2.9 Li + per V 2 O 5 ) with a capacity fading on intercalation-deintercalation cycles below 0.5% per cycle.

V2O5 aerogel-like lithium intercalation host

Abstract Thin self-standing films and powders of highly amorphous V2O5 have been prepared via a combined sol-gel and solvent exchange procedure. The amorphous V2O5 is a highly interconnected porous material with very thin solid walls and shows a unique lithium intercalation behavior. Electrochemical tests performed on composite cathodes made by mixing the material with carbon particles demonstrated a very high lithium insertion capacity.

Performance of copper-doped V2O5 xerogel in coin cell assembly

Copper-doped, vanadium pentoxide xerogel is prepared through a simple sol–gel procedure, followed by heterogeneous doping and freeze-drying. Composite cathodes were formed by spray-coating a mixture of the Cu-doped material, carbon, and binder onto aluminum foils. The composite cathodes were studied in 2016 coin cells with lithium anodes and supported liquid electrolyte. The electrochemical performance of the doped material is excellent. Up to 2.2 mol of lithium per mol of doped V2O5 can be reversibly intercalated. The composite cathodes also showed very high intercalation rate performance and an excellent cyclability with no capacity fading over a few hundred cycles (>450).

Li ‐ Mn ‐ O Aerogels

The materials described here were obtained by drying liquid gels at low‐surface tension conditions, a process which produces high surface area disordered materials in which the microporous structure can be controlled with simple manipulations of the parent gel. The technique of synthesis is simple, inexpensive, and in general may be applied to other intercalation compounds synthesized via sol‐gel routes. The aerogels offer a direct way to study the interconnected solid network assembled by sol‐gel processes, which would collapse if processed by normal dehydration. Since the interconnected solid network is preserved in the aerogel, the properties such as high specific surface area and high specific energy observed in the aerogel represent inherent properties of the network formed in the liquid gel stage. ©1999 The Electrochemical Society

Lithium-ion batteries for hearing aid applications: II. Pulse discharge and safety tests

Abstract Rechargeable lithium-ion batteries were designed to meet the power requirements of hearing aid devices (HADs). The batteries were designed in a 312-button cell size, compatible with existing hearing aids. The batteries were tested to evaluate the design and the electrochemical performance, as they relate to a typical hearing aid application. The present report covers the pulse capabilities, cycle life and preliminary safety tests. The results are compared with other battery chemistries: secondary lithium-alloy and nickel–metal hydride batteries and primary Zn–air batteries. The cell AC impedance was stable over the frequency range between 1 and 50 kHz, ranging between 5 Ω at the higher frequency and 12 Ω at the lower extreme. Pulse tests were consistent with these values, as the cells were capable of providing a series of 100 mA pulses of 10-s duration. The safety tests suggest that the design is intrinsically safe with respect to the most common types of abuse conditions.

Electrochemical and synchrotron XAS studies of lithium intercalation into vanadium pentoxide aerogels and nanocomposites

Abstract Vanadium pentoxide aerogels are pillared nanocomposites with exceptional stability, intercalation capacity, and reversibility. X-ray absorption spectroscopy (XAS) measurements on pristine and doped materials have revealed details of the oxidation state and local structure of the host material and of the polyvalent doping species. XANES measurements at the Cu K-edge for Cu 0.1 V 2 O 5 show the atomic level reversibility of the structure upon Li + insertion/release cycling.

Lithium-ion batteries for hearing aid applications: I. Design and performance

Abstract Rechargeable batteries have been designed for powering hearing aid devices (HAD). The cells, based on the lithium-ion chemistry, were designed in a size that is compatible with the existing HAD. The 10 mA h batteries were tested to characterize the design and the electrochemical performance from the point of view of a typical HAD application. Results are presented for constant-current tests, first-cycle conditions, charge voltage cut-off, rate performance, and cycle life. The pulse capabilities and the preliminary safety tests of the batteries will be presented in a following report. The results of the lithium-ion HAD cells developed in this project are compared with other battery chemistries: lithium-alloy and nickel–metal hydride secondary batteries and Zn–air primary batteries.