High-Voltage All-Solid-State Thin-Film Lithium Batteries Enabled by LiF Interlayer.

All-solid-state thin-film lithium batteries (TFBs) with high voltage are crucial for powering microelectronics systems. However, the issues of interfacial instability and poor solid contact of cathode/electrolyte films have limited their application. In this work, the preferentially orientated LiCoO2 (LCO) nanocolumns and the LCO/LiPON/Li TFBs are fabricated by in situ heating sputtering. By introducing the LiF interlayer, the solid contact of the LCO/LiPON interface is improved, enabling the high-voltage TFBs. The elemental diffusion, morphology change, and interfacial deterioration are suppressed, as demonstrated by various in situ and ex situ tests. As a result, the LCO/LiF/LiPON/Li TFB exhibits a more stable and higher capacity compared to other TFBs. This work provides guidance to improve the solid contact of TFBs and increase the performance of all-solid-state lithium batteries.

Regulation of Interfacial Lattice Oxygen Activity by Full-Surface Modification Engineering towards Long Cycling Stability for Co-Free Li-Rich Mn-Based Cathode.

The construction of a protective layer for stabilizing anion redox reaction is the key to obtaining long cycling stability for Li-rich Mn-based cathode materials. However, the protection of the exposed surface/interface of the primary particles inside the secondary particles is usually ignored and difficult, let alone the investigation of the impact of the surface engineering of the internal primary particles on the cycling stability. In this work, an efficient method to regulate cycling stability is proposed by simply adjusting the distribution state of the boron nickel complexes coating layer. Theoretical calculation and experimental results display that the full-surface boron nickel complexes coating layer can not only passivate the activity of interface oxygen and improve its stability but also play the role of sharing voltage and protective layer to gradually activate the oxygen redox reaction during cycling. As a result, the elaborately designed cobalt-free Li-rich Mn-based cathode displays the highest discharge-specific capacity retentions of 91.1% after 400 cycles at 1 C and 94.3% even after 800 cycles at 5 C. In particular, the regulation strategy has well universality and is suitable for other high-capacity Li-rich cathode materials.