Towards the development of a novel bipolar-based battery in aqueous electrolyte: Evaluation of the electrochemical properties of NiCu based hydroxide electrodes fabricated on Ni-mesh and graphite composite current collectors

The use of bipolar electrodes in rechargeable batteries can improve specific power, simplify cell design, and reduce manufacturing costs. However, bipolar-based batteries still suffer from many drawbacks. Therefore, developing high-performance active materials and developing improvement strategies encompassing the entire cell's design is essential. The current collector significantly impacts the viability of mass production; however, it is the most neglected feature of electrochemical energy storage devices. The current collector serves a dual purpose; it allows the movement of electrons among active electrode material and provides mechanical support. It can also act as transportation of current to terminals of the battery. This study constructed a novel bipolar battery cell utilizing graphite as a current collector, and its discharge capacities for Ni-Fe battery applications were evaluated. Monopolar NiFe cells, one using a graphite substrate current collector and the other using a Ni-mesh current collector, were used for comparison. The monopolar-based electrode coated onto a graphite substrate demonstrated a 29% (199 mAh/g) higher discharge capacity than the Ni-mesh-based electrode (142 mAh/g) after the 100th cycle. In contrast, the bipolar-based NiFe battery cell resulted in a discharge capacity of 158 mAh/g after the 100th cycle, corresponding to a coulombic efficiency of 72%.