CoO AS ADDITIVE IN POSITIVE ELECTRODE OF NICKEL-METAL HYDRIDE BATTERY

A series of positive electrodes for Ni/MH battery were fabricated by addition of CoO.The morphology and microstructure of the electrodes were examined by SEM and EDS, and electrochemical behavior was investigated in three-compartment appliances at room temperature.The electrochemical performance of the positive electrodes with CoO was improved. Under the same charge-discharge cycle, the electrodes with CoO showed higher specific capacity, lower charge mean voltage and higher discharge mean voltage. But ...

Electrode Characteristics of MmNi_5-based Alloys for Nickel-Metal Hydride Batteries

Negative electrodes of the Ni-metal hydride battery were made from hydrogen storage alloy Mm0.9Ti0. 1Ni3. 9Mn0.4Co0.4Al0.3 mod fied by coating with Ni or mixing with Co powder. The cell volume expansion of hexagonal structure was about 12 % after coating with 11 % Ni on the alloy Surface,When this alloy was mixed with Co powder. the discharge capacity and the utilization efficiency of the hydrogen storage alloy increased. When the alloy was coated with 11 wt-% Ni and also mixed with 10 wt-% Co powder. the capacity decay for a small sealed cylindrical cell (AA size. 1 Ah) was only about 4 % after 200 cycles

Electrode Characteristics of MmNi_5－type Alloys for Nickel－metal HydrideBatteries

Negative electrodes of the nickel-metal hydride battery were made from hydrogen storage alloy Mm0.9Ti0.1Ni3.9Mn0.4Co0.4Al0.3 modified by coating with nickei and mixing with cobalt powder. When the 10wt% cobalt powder was mixed with this alloy, the discharge capacity increased from 262 mAh/g to 300 mAh/g at 300K. When the alloy was coated with 11wt% nickel and mixed with 10wt% cobalt powder, the discharge capacity decay for a sealed cell (AA size, 1 Ah) was only about 4% after 200 cycles.

Recovery of rare earths from acid leach solutions of spent nickel-metal hydride batteries using solvent extraction

The extraction of rare earths from acid leach solutions of spent nickel-metal hydride batteries using a primary amine ex- tractant of N 1923 was studied. The effects of feed pH, temperature, agitation rate and time on the extraction of rare earths, as well as stripping agent composition and concentration, phase ratio on the stripping were investigated. In addition, the extraction isotherm was determined. The pilot plant test results showed that the extraction of rare earths reached 99.98% after a five-stage counter current extraction. The mixed rare earths oxalates with the 99.77% purity of rare earth elements and impurity content less than 0.05% were obtained by the addition of oxalic acids in loaded strip liquors. The extractant exhibited good selectivity of rare earths over base metals of iron, nickel, copper and manganese.

Separation and recovery of rare earth from waste nickel-metal hydride batteries by phosphate based extraction-precipitation

A novel type of extraction-precipitation strategy based on phosphate was developed to recover rare earth(RE,i.e.,La,Ce,Nd,and Pr)from waste nickel-metal hydride(NiMH)batteries.This method does not require saponification and organic solvents.The novel phosphates,i.e.,dibenzyl phosphate(DBP),diphenyl phosphate(DPP),triphenyl phosphate(TPP)were studied as extraction-precipitants.DBP has high precipitation efficiencies for RE^(3+),which can reach 97.84%,100%,100%and 99.77%,respectively.In addition,the precipitation efficiencies of Mn^(2+),Co^(2+)and Ni^(2+)are less than 1.75%.DBP-RE has the largest particle size(D10=52.6μm,D50=135.35μm,D90=296.08μm),which is much larger than the precipitations formed by NH_(4)HCO_(3),H_(2)C2O_(4),CaO and MgO.The larger precipitation particle sizes contribute to improving the solid-liquid separation efficiency.With 3 mol/L hydrochloric acid,the stripping efficiency of DBP-RE reaches 98.60%,and the purity of recovered RE is 99.85%.The regenerated DBP can be directly used for the recycling extraction.Therefore,the novel extraction-precipitation strategy is a green and sustainable separation method.

Effects of flaky rare earth oxide additives on the high temperature performance of nickel electrodes

Effects of flaky rare earth oxide additives including Er2O3,Tm2O3,and Yb2O3,Lu2O3 on high temperature and high rate discharge performance of nickel electrodes were investigated.The discharge efficiency at 0.2C reached 96% at 60 oC for electrodes with 1 at.% flaky rare earth oxides.The high rate discharge performance for electrodes with flaky rare earth oxides were improved significantly,for example,discharge efficiency at 5C improved from 50% to 70%.The results showed that the end charging potential of the ...