In this work, a new bulk Li_3.6PO_3.4N_0.6 crystalline polymorph has been prepared from low-cost precursors, following a simple ball-milling procedure. The densified powder exhibits a conductivity of 5.0 × 10^–6 S cm^–1 at 70 °C and an electrochemical stability allowing operation with high-voltage materials up to 5.0 V vs Li/Li⁺. Stripping and plating of lithium in a symmetric cell demonstrates the forthcoming bulk application of LiPON in electrochemical devices. Widening the use of lithium phosphorus oxynitride compositions to bulk solid-state batteries will have relevant implications because of its unique compatibility with both high-voltage electroactive materials and lithium metal and its low density.

Solid State Batteries (SSBs) are the best candidates to overcome the safety and energy density drawbacks of conventional Li-ion. However, this technology is still relatively nascent in development and needs to offer competitive energy density so as to meet current demands of devices, especially those related to emerging electric vehicles. This work focuses on cell characteristics having the potential to reach 250 Wh kg ⁻¹ and 500 Wh l ⁻¹ in a manufacturing environment. The electrode and the solid electrolyte were carefully selected based on the results of theoretical energy density calculations, also taking into account the the scalability of their processing. The reported cells rely on a cathode which includes the high voltage active material NMC622, with loadings up to 1.6 mAh cm ⁻² , a composite electrolyte based on garnet-type oxide (Li ₇ La ₃ Zr ₂ O ₁₂ ) and poly(ethylene oxide) (PEO), and a Li metal anode. As a consequence of a particular conditioning, when cycled at 70 °C the cells delivered 91% of their theoretical capacity. To our knowledge, this is the first time that a PEO-based electrolyte has been successfully cycled with a high-voltage cathode. Pouch cells of 30 mAh have also been tested at 55 °C. These promising results highlight the feasibility of the industrial development of competitive SSBs.

Solid state batteries are the next generation of safe energy storage devices offering high energy and power. Li₇La₃Zr₂O₁₂ garnets are fast Li-ion conductors and promising electrolytes to be used in solid-state batteries. However, they react with humid air to form LiOH and Li₂CO₃, reducing the ionic conductivity. In this work, the effect of heat treatment on local Li mobility in LLZO and the chemical evolution and phase transitions during the heating are investigated by a combination of solid state NMR, Raman, and XRD diffraction techniques. The results show that the activation energy for Li jumps obtained by variable temperature solid state NMR decreases after heat treatment at 750 °C and the Li dynamics are comparable to those of sintered pellets. Additionally, we show that the pretreatment of powders is an effective approach for obtaining garnet-rich composite electrolytes with better flexibility and garnet-polymer interphases, improving the prospects of this material towards processing.

Additive manufacturing (AM) techniques using advanced functional materials are attracting strong attention in the field of all solid-state lithium batteries (ASSBs) since they are considered as innovative approaches that will pave the way for cheaper, safer, and customizable batteries with exceptional volumetric energy density. In the present work, stereolithography (SLA) is presented as a suitable technique to produce complex-shaped Li_1.5Al_0.5Ge_1.5P₃O₁₂ (LAGP) full-ceramic electrolytes from glass feedstock. Printed electrolytes showed an ionic conductivity in good agreement with LAGP fabricated by conventional techniques (σ = 6.42 × 10⁻⁵ S cm⁻²). Moreover, 3D printed LAGP corrugated membranes with interfacial area increased by 15% were fabricated showing an equivalent reduction of the area specific resistance. Symmetrical cells with lithium metal electrodes were used to study the stripping and plating behaviour of LAGP printed electrolytes coated with a germanium protective interlayer deposited via thermal evaporation. The symmetric cells showed a stable cycling performance over 250 hours demonstrating the stability of the designed cells. The innovative approach reported here represents the first step for the next generation of ASSBs based on LAGP, offering new degrees of freedom for the manufacturing of full ceramic electrolytes with a complex shape.