Effect of Pt and Au current collector in LiMn2O4 thin film for micro-batteries

All-Solid-State Thin Film Lithium/Lithium-Ion Microbatteries for Powering the Internet of Things

As the world steps into the era of Internet of Things (IoT), numerous miniaturized electronic devices requiring autonomous micropower sources will be connected to the internet. All-solid-state thin-film lithium/lithium-ion microbatteries (TFBs) combining solid-state battery architecture and thin-film manufacturing are regarded as ideal on-chip power sources for IoT-enabled microelectronic devices. However, unlike commercialized lithium-ion batteries, TFBs are still in the immature state, and new advances in materials, manufacturing, and structure are required to improve their performance. In this review, the current status and existing challenges of TFBs for practical application in internet-connected devices for the IoT are discussed. Recent progress in thin-film deposition, electrode and electrolyte materials, interface modification, and 3D architecture design is comprehensively summarized and discussed, with emphasis on state-of-the-art strategies to improve the areal capacity and cycling stability of TFBs. Moreover, to be suitable power sources for IoT devices, the design of next-generation TFBs should consider multiple functionalities, including wide working temperature range, good flexibility, high transparency, and integration with energy-harvesting systems. Perspectives on designing practically accessible TFBs are provided, which may guide the future development of reliable power sources for IoT devices.

Tunnel Intergrowth Lix MnO2 Nanosheet Arrays as 3D Cathode for High-Performance All-Solid-State Thin Film Lithium Microbatteries

All-solid-state thin film lithium batteries (TFBs) are proposed as the ideal power sources for microelectronic devices. However, the high-temperature (>500 °C) annealing process of cathode films, such as LiCoO₂ and LiMn₂ O_4, restricts the on-chip integration and potential applications of TFBs. Herein, tunnel structured Li_x MnO₂ nanosheet arrays are fabricated as 3D cathode for TFBs by a facile electrolyte Li⁺ ion infusion method at very low temperature of 180 °C. Featuring an interesting tunnel intergrowth structure consisting of alternating 1 × 3 and 1 × 2 tunnels, the Li_x MnO₂ cathode shows high specific capacity with good structural stability between 2.0 and 4.3 V (vs. Li⁺ /Li). By utilizing the 3D Li_x MnO₂ cathode, all-solid-state Li_x MnO₂ /LiPON/Li TFB (3DLMO-TFB) has been successfully constructed with prominent advantages of greatly enriched cathode/electrolyte interface and shortened Li⁺ diffusion length in the 3D structure. Consequently, the 3DLMO-TFB device exhibits large specific capacity (185 mAh g^-1 at 50 mA g^-1 ), good rate performance, and excellent cycle performance (81.3% capacity retention after 1000 cycles), outperforming the TFBs using spinel LiMn₂ O₄ thin film cathodes fabricated at high temperature. Importantly, the low-temperature preparation of high-performance cathode film enables the fabrication of TFBs on various rigid and flexible substrates, which could greatly expand their potential applications in microelectronics.

Electrochemical Methods for Lithium Recovery: A Comprehensive and Critical Review

Due to the ubiquitous presence of lithium-ion batteries in portable applications, and their implementation in the transportation and large-scale energy sectors, the future cost and availability of lithium is currently under debate. Lithium demand is expected to grow in the near future, up to 900 ktons per year in 2025. Lithium utilization would depend on a strong increase in production. However, the currently most extended lithium extraction method, the lime-soda evaporation process, requires a period of time in the range of 1-2 years and depends on weather conditions. The actual global production of lithium by this technology will soon be far exceeded by market demand. Alternative production methods have recently attracted great attention. Among them, electrochemical lithium recovery, based on electrochemical ion-pumping technology, offers higher capacity production, it does not require the use of chemicals for the regeneration of the materials, reduces the consumption of water and the production of chemical wastes, and allows the production rate to be controlled, attending to the market demand. Here, this technology is analyzed with a special focus on the methodology, materials employed, and reactor designs. The state-of-the-art is reevaluated from a critical perspective and the viability of the different proposed methodologies analyzed.

Miniaturized Energy Storage Devices Based on Two-Dimensional Materials

A growing demand for miniaturized biomedical sensors, microscale self-powered electronic systems, and many other portable, wearable, and integratable electronic devices is continually stimulating the rapid development of miniaturized energy storage devices (MESDs). Miniaturized batteries (MBs) and supercapacitors (MSCs) were considered to be suitable energy storage devices to power microelectronics uninterruptedly with reasonable energy and power densities. However, in addition to similar challenges encountered with electrode materials in conventional energy storage devices, their performances are also greatly affected by microfabrication technologies, as well as the challenges of how to realize stable and high-performance MESDs in such a limited footprint area. Benefiting from the unique architectural engineering of two-dimensional materials and the emergence of precise and controllable microfabrication techniques, the output electrochemical performances of MSCs and MBs are improving rapidly. This minireview summarizes recent advances in MSCs and MBs built from two-dimensional materials, including electrode/device configuration designs, material synthesis, microfabrication processes, smart function incorporations, and system integrations. An introduction to configurations of the MESDs, from linear fibrous shapes, planar sandwich thin-film or interdigital structures, to three-dimensional configurations, is presented. The fundamental influences of the electrode material and configuration designs on the exhibited MB/MSC electrochemical performances are also highlighted.