Research on Li-ion accumulators that we carried out in 2010 – 2011 with the help of 500 W test bench, demonstrated significant rise of energy efficiency during accumulator discharge, probably due to reduction of polarization component of internal resistance.
Fig. 1-3 show the extracted power – relative capacity and specific energy, and relative capacity – load current diagrams that we have obtained for a Li-ion accumulator Kokam (11 A*h, 12 V) at load current 2 – 3 C. The diagrams show that during accumulator discharge through electronic separator (ES) the extracted energy grows significantly in comparison with its discharge directly to load (with the same power and load current levels). The capacity (in A*h) extracted from the accumulator during its discharge through ES by the current 2.5 C, increases by 23%. When the accumulator is discharged through ES, the specific energy at specific power 160 W, that corresponds approximately to average discharge current 2.5 C (Fig. 2), also increases by 23%. The use of ES provides extracted power constancy (Fig.1) during nearly the whole discharge period (till 100% of relative capacity); without electronic separator a 30% smaller power level is maintained only till 80% of relative capacity. In other words, we have succeeded to extract all accumulated capacity (in A*h) even during load current of about 3 C, that is definitely an important achievement.
Figures
Fig.1 |
Fig.2 |
Fig.3 |
Fig.4 |
Fig. 4 shows temperature change diagrams on the surface of Li-ion accumulator battery during its discharge through the electronic separator and without it. A lower accumulator heating during its discharge through the separator denotes the decrease of its internal resistance. As far as an accumulator battery resource (endurance) is largely defined by heat loss during its operation, it is reasonable to say that the use of the electronic separator increases this very resource.
English
Русский
