Tatsuo Horiba

X-ray photoelectron spectroscopy analyses of lithium intercalation and alloying reactions on graphite electrodes

Abstract Electrochemical lithium intercalation reactions occurring in silver-supported graphite anodes were investigated by X-ray photoelectron spectroscopy (XPS). The binding energy of Li(1s) of intercalating lithium was higher than that of lithium metal, which suggests that lithium exists in the form of a positive ion in the graphite layers. The core level of the C(1s) signal of lithium intercalated graphite was higher than that of graphite, which implies that the carbon in lithium-intercalated graphite has a negative charge. This finding agrees with previous XPS studies indicating that carbon has a negative charge in a graphite-intercalation compound produced by a molten lithium intercalation reaction to graphite. Lithium carbonate, lithium fluoride and organic compounds were produced on the graphite surfaces in charge/discharge reactions in 1 M LiPF 6 /EC—DMC electrolytic solution. It was also confirmed that the initial charge current supplied to the graphite electrode with a potential between 2.8 and 0.6 V did not cause a lithium-intercalation reaction. It caused, however, other reactions such as decomposition of the electrolytic solution and production of passivating films.

Polymer electrolyte hydrogen-oxygen fuel cell where the polymer electrolyte has a water repellency gradient and a catalytically active component concentration gradiem across oxygen electrode

The polymer electrolyte type hydrogen-oxygen fuel cell of the present invention comprises an oxygen electrode and a hydrogen electrode, a polymer electrolyte membrane provided between the oxygen electrode and hydrogen electrode and electron conductors provided on the side of the electrodes which is opposite to the electrolyte side and the oxygen electrode comprises a catalytically active component, a carrier for the catalytically active component and a binder and has such a gradient in water repellency across the thickness that the water repellency is highest in the area adjacent to the electrolyte and lowest in the area adjacent to the conductor. In this fuel cell, flooding of water at the interface between the oxygen electrode and the electrolyte can be prevented.

Physical and electrochemical characterization of quaternary Li-Mn-V-O spinel as positive materials for rechargeable lithium batteries

Quaternary Li-Mn-V-O spinels formed from heating mixtures of LiNO{sub 3}, MnCO{sub 3}, and NH{sub 4}VO{sub 3} around 350{degree} have been characterized by electrochemical measurement, X-ray photoelectron spectroscopy, X-ray diffractometry, {sup 7}Li-NMR, and magnetic susceptibility measurements. These results were compared with those for ternary Li-Mn-O spinels prepared at 350 and 850 C. The compositions of the quaternary and ternary spinels formed at 350 C were shown to be x(Li{sub 2}O)Mn{sub 2}O{sub 4} {center_dot} yV{sub 2}O{sub 5} (x = 0.5 {approximately} 1, y = 0 {approximately} 0.4). The cubic a{sub 0}-lattice parameter and specific density of the quaternary spinels increased with increasing vanadium content in the spinel structure. The {sup 7}Li-NMR measurements revealed that the quaternary spinels did not show any Knight shift, while the ternary Li-Mn-O spinels formed at 350 and 850 C had a large Knight shift of 490 {approximately} 535 ppm in reference to LiCl. Furthermore, the measurement of the magnetic susceptibility indicated that the ternary and quaternary spinels formed at 350 C are paramagnetic and the ternary LiMn{sub 2}O{sub 4} prepared at 850 C is antiferromagnetic.

Design and performance of 10 Wh rechargeable lithium batteries

Abstract New metal—carbon composite anodes were developed by a chemical deposition method of metal particles onto graphite powder. Silver—graphite composites consisted of ultrafine silver particles on a graphite surface, exhibiting a large specific volume capacity of 468–505 Ah/l which may be due to Li Ag alloy formation. The Ag—graphite anodes also showed excellent cycleability over 700 charge/discharge cycles with only 3% capacity loss. 10 Wh class rechargeable lithium batteries with energy densities of 270–300 Wh/l were manufactured using Ag—graphite anodes and cathodes of LiNiO 2 or LiCoO 2 . Little capacity loss in these batteries was found even after 250 cycles because of the highly durable Ag—graphite anodes.

Thermodynamic and Kinetic Studies of Electrochemical Lithium Insertion into Quaternary Li‐Mn‐V‐O Spinel as Positive Materials for Rechargeable Lithium Batteries

The thermodynamics and kinetics of the lithium insertion process into the quaternary spinel Li[sub x]Mn[sub 2]O[sub 4] [times] yV[sub 2]O[sub 5](x = 0.5 to 3, y = 0.25 to 0.5) have been studied. The partial molar quantities [Delta][bar G][sub Li(x)], [Delta][bar H][sub Li(x)], and [Delta][bar S][sub Si(x)] of lithium in the quaternary spinels have been determined from electromotive force-temperature measurements performed using 1M LiClO[sub 4] solution of propylene carbonate in the temperature range from 298 to 330 K. These thermodynamic functions varied with the lithium concentration in the oxide structure and a major variation was observed around x = 1 in Li[sub x]Mn[sub 2]O[sub 4] [times] yV[sub 2]O[sub 5]. The chemical diffusion coefficient for lithium [tilde D] in the spinel oxides has been measured as functions of the lithium composition and temperature by a current-pulse relaxation technique. The values of [tilde D], obtained in the x value range from 0.5 to 1.0 at 298K, were found to be several orders of magnitude higher than those in the x value range from 1.3 to 2.5. The lithium self-diffusion coefficient D[sub Li], partial lithium-ion conductivity and activation energy for lithium diffusion have been calculated.

Lithium cell treating method and lithium cell treating apparatus

A treating fluid is in contact with a negative electrode containing lithium of a lithium cell under a first condition to react a surface portion of the negative electrode, and a treating fluid is in contact with lithium existing inside an article formed on the surface of the above-described negative electrode under a second condition. The cells can be effectively treated under safety condition to collect either the valuable substances, or the cell constructive components.

Method and apparatus for treatment of a battery containing alkali metal.

A safe and controllable method of treating a secondary battery having at least one component containing alkali metal, comprises the steps of opening the battery casing, and introducing a gas containing at least one of water vapor and alcohol vapor into a closed chamber containing the battery thereby to form alkali metal hydroxide. To control hydrogen concentration, the rate of introduction of water and/or alcohol vapor may be varied. Apparatus for carrying out this method is also described.