While increasing the multifunction of wearable devices such as smart watch, earphone, and glasses, the run-time of battery is getting more important to be a competitive product in the wearable market. In order to get more reliable and longer lasting battery, the concepts of 3D battery architecture have been suggested to improve energy density [1].

Several 3D microbattery architectures have been proposed to maximize the areal energy density and rate discharge capability by maintaining short ion-transport distances between cathode and anode [2]. However, the implementation of high areal capacity 3D electrode is difficult to fabricate due to the limitation of manufacturing processing [3]. Moreover, conventional fabrication technology of the thin film electrolyte cannot make good step coverage of the 3D conformal electrolyte.

In this research, we propose technical approaches to fabricate a high energy density 3D battery structure with good step coverage of the 3D conformal electrolyte. First, we developed a high aspect ratio (=h/w, where h is height and w is width of cathode) 3D cathode which consists of only LiCoO₂ with high electrode density without any binder and conductive additives. And then, two kinds of different solid electrolyte layers, LLZO and LiPON, were applied to the 3D conformal coating on the 3D cathode by sol-gel and CVD processing. The process of sol gel and CVD efficiently improved step coverage of 3D conformal electrolyte. Subsequently, Li-metal was evaporated to make a bed for striping and plating as anode. Finally, the 3D solid state battery was evaluated and analyzed for the feasibility study of a next generation battery.

References

[1] Jeffrey W. Long et al, Chemical review, 104 (2004) 4463-4492

[2] Stefania Ferrari et al, J. Power Sources, 286 (2015) 25-46

[3] Matthew Roberts et al, J. Mater. Chem, 21 (2011) 9876-90