Development of complex hydride-based all-solid-state lithium ion battery applying low melting point electrolyte

Abstract A thermally durable all-solid-state lithium ion battery composed of a complex hydride, oxide electrolytes, and LiNi 1/3 Mn 1/3 Co 1/3 O 2 active material is developed. This battery exhibits a discharge capacity of 56 mAh g −1 , and the tenth capacity retention ratio is 29% at 150 °C owing to the large contact resistance between the electrolyte layer and the composite positive electrode layer. This large contact resistance is reduced by introducing an adhesive layer comprised of a mixture of LiBH 4 and LiNH 2 that is easily melted by thermal treatment and fills the voids and pores at the interface between the two layers. As a result, repeated charge-discharge cycles are successfully demonstrated at 150 °C with a high discharge capacity and discharge capacity retention ratio. The first discharge capacity is enhanced to 114 mAh g −1 and the capacity retention ratio at the tenth cycle is improved to 71%. These results demonstrate that using an adhesive layer is an effective measure to reduce the contact resistance and thereby enhance the performance of the battery.