Crystal Water-Assisted Additional Capacity for Nickel Hydroxide Anode Materials

To further increase the energy density of rechargeable batteries to meet the rapidly growing needs of high-energy consuming devices, various materials are tested as anode materials. Some of these newly developed anode materials exhibit anomalously high capacities that exceed their theoretical values. Advanced analytical techniques have revealed that unconventional reaction mechanisms account for these extra capacities. However, despite the potential to take current battery technology development to the next level, research on the utilization of these reactions is currently limited. Herein, a new strategy is proposed to maximize the reaction of -OH components by using crystal water to increase the extra capacity obtained from the abnormal reactions of LiOH species. In addition to the LiOH phase formed by the conversion reaction of metal hydroxides, the H2O inside Ni(OH)(2) crystals contributes to the formation of LiOH, which then reacts with lithium. As a result, water-containing Ni(OH)(2) exhibits greater reversible capacities than bare Ni(OH)(2) and NiO, thereby confirming the beneficial effects of crystal water. This novel concept for the enhancement of electrochemical ion storage capacities through the introduction of crystal water to conversion-based anode materials can expand the design factors for maximizing the available capacities of active materials.