H.-J. Sohn

Nanosized Sn–Cu–B alloy anode prepared by chemical reduction for secondary lithium batteries

Nanosized Sn–Cu–B alloy powder is synthesized by chemical reduction to be used as an alternative anode material for secondary lithium batteries. The alloy powder consists of two phases, i.e. mainly η′-Cu6Sn5 and a small amount of e-Cu3Sn. The reaction of Cu6Sn5 with lithium proceeds in two steps. Lithium is inserted into the Cu6Sn5 lattice first as LixCu6Sn5, which is isostructural with Li2CuSn, followed by alloying with tin, reversibly even after long cycling. The cycle performance of the nanosized Cu6Sn5 electrode is significantly enhanced in comparison with that of the same material prepared by sintering or mechanical alloying.

Mechanochemical synthesis and electrochemical characteristics of Mg2Sn as an anode material for Li-ion batteries

Abstract Mg 2 Sn prepared by mechanochemical process was examined as an alternative anode material for Li-ion batteries. Electrochemical tests demonstrated that the initial charge and discharge capacity of Mg 2 Sn was 556 and 460 mAh/g, respectively. Ex-situ XRD and differential capacity plots showed that lithium inserted into the Mg 2 Sn lattice first followed by alloying with Sn. Contrary to the isostructural Mg-based intermetallic compound, Mg 2 Si, alloying reaction between Li and Mg was not observed during lithiation of Mg 2 Sn. Mg 2 Sn showed better capacity retention characteristic than that of Mg 2 Si. It is thought that this may be attributed to that Mg formed at Mg 2 Sn electrode did not react with lithium, and also active materials of Mg 2 Sn electrode changed from Mg 2 Sn to Sn with the increase of cycles. Also Mg 2 Sn showed improved cycle performance under restricted voltage range due to prevention Sn from aggregation into larger clusters.

Characterizations of a new lithium ion conducting Li2O–SeO2–B2O3 glass electrolyte

Abstract A new lithium-ion conducting glass electrolyte, x Li 2 O–(1− x )(ySeO 2 –(1− y )B 2 O 3 ) was prepared by melt quenching technique and characterized using various analytical techniques. 0.5Li 2 O–0.5(ySeO 2 –(1− y )B 2 O 3 ) glass shows typical mixed-former behavior and the conductivity increased significantly compared with binary Li 2 O–B 2 O 3 glass with a maximum conductivity close to 10 −6 S/cm at y =0.5. Based on FT-IR and DSC analyses, SeO 2 acts either glass modifier or glass former as the composition of SeO 2 changes. The glass transition temperature is found to be about 300 °C, and the glass is electrochemically stable without any significant decomposition reaction between 0 and 5 V (vs. Li/Li + ).

Particulate-reinforced Al-based composite material for anode in lithium secondary batteries

Particulate-reinforced Al/SiC composite materials are prepared by ball-milling technique to be used as an anode material for lithium secondary battery. The microstructure of the composite powders show that the SiC particles are embedded homogeneously in the Al matrix. This feature is distinctively different from any other active/inactive composite anode materials reported recently. The cycle performance of these composite electrodes is superior to that of an unreinforced aluminium electrode. This improved cycelability may be due to an enhanced mechanical stability of the electrode.

Thin film lithium ion conducting LiBSO solid electrolyte

Thin films of 1–2 μm amorphous solid electrolytes, (1−x)LiBO2–xLi2SO4 (LiBSO), were fabricated by RF magnetron sputtering with a wide range of compositions, i.e. x=0.4–0.8, which are beyond the glass-forming region by conventional melt quenching method. The ionic conductivity of the electrolyte at room temperature increased with x and showed a maximum at x=0.7, about 2.5×10−6 S/cm. For higher x, (x>0.7), the conductivity began to decrease due to the partial crystallization. In addition, the electrolyte was stable up to 5.8 V vs. Li/Li+. LiBSO thin film electrolyte was incorporated into Li/TiS2 microbattery, showing a good cycling performance.

Electrowinning of tellurium from alkaline leach liquor of cemented Te

The electrochemical behaviour of tellurium in 2.5 M NaOH solution was studied for the recovery of tellurium from alkaline leach liquor of cemented Te using steady state polarization and cyclic voltammetry. The deposition characteristics and the potential range for a stable deposit of tellurium were also investigated. The morphology of deposited Te in alkaline solution showed a very porous nature and needlelike radial growth. The potential range for stable electrodeposition was between −0.8 V and −0.95 V (vs Hg/HgO electrode), but electrowinning could be carried out at more negative potentials due to the disproportionation reaction of Te22−. Laboratory-scale electrowinning experiments were performed under different operating voltages, temperatures and initial Te concentrations. The current efficiency was about 85–90% for 50% recovery and about 50–60% for 90% recovery. The purity of electrodeposited Te was higher than 99.95%.

Leaching behaviour of tin with oxygen in recycled phenolsulfonic acid tin plating solutions

The dissolution characteristics of metallic tin with oxygen in recycled phenolsulfonic acid (PSA) tin plating bath to compensate tin consumed during the previous plating operation were investigated using electrochemical methods and leaching experiments at 30 °C. Electrochemical polarization data indicate that the diffusion of dissolved oxygen is the rate determining step and this is confirmed by leaching experiments. The sludge formed due to further oxidation of stannous ions during leaching in PSA tin plating solutions contains approximately 40 wt % Sn.