Fabrication of Industrial Ni-Zn Pocket-Type Secondary Battery

We fabricated the industrial-scale high-capacity Ni-Zn pocket-type secondary batteries with 100-Ah capacity, and connected in parallel to produce 300-Ah and optimized the performances. The pocket-type battery, which has a high capacity, has various advantages, however, due to a flooded-type structure containing a large volume of electrolytes, operational problems such as evaporation of the electrolyte and dissolution of active materials including zinc have been noted. To resolve these problems, we formulated different compositions of active materials and fabricated 100-Ah batteries and constructed 300-Ah large-capacity system through various pretreatments. In the 100-Ah battery, we identified the effects of binders—ingredients of the active material—and different electrolyte compositions. For the 300-Ah system, the effect of coating the membranes with polymer gel is tested. Binders and electrolytes play critical roles in enhancing the pocket-type battery performance; and thus we tried various mixtures of binders and electrolytes and optimized this battery for industrial applications. The 300-Ah pocket-type system coated with a gel polymer achieved the performance maintaining 75% retention capacity at 80% DOD for 350 cycles and showing sufficient performance for commercialization.