Direct Recycling of All-Solid-State Thin Film Lithium Batteries with Lithium Anode Failure

Abstract

All-solid-state thin film lithium batteries (TFBs) are regarded as the ideal power source for microelectronics in the upcoming era of the Internet of Things, owing to their solid-state architecture, flexible size and shape, long cycle life, low self-discharge rate, and facile miniaturization. Even though tremendous improvements have been made in TFBs in the last decades, recycling of TFBs, which is supposed to be a serious issue in the future, is rarely studied. With continuous TFB market expansion, the sustainable development of TFBs is becoming an increasingly important research topic. To date, Li anode failure has been regarded as the most common reason for the failure of TFBs due to the following aspects of Li metal anode: strong reactivity with moisture, large volume change during cycling, and inevitable dendrite growth during Li plating. In this work, a facile recycling strategy is developed based on the most commonly used TFBs of LiCoO2 (LCO)/lithium phosphorus oxynitride (LiPON)/Li (F-TFB). Our findings indicate that the Li anode in F-TFB is partially oxidized during cycling with noticeable surface morphology change, which leads to an obvious increase in Li/LiPON interfacial resistance associated with rapid capacity loss. To directly recycle the F-TFB, we developed a simple method to remove the spent Li anode by dissolving the metallic Li metal of the F-TFB in an ethanol solution. The efficient dissolution of metallic Li allows the oxidized Li residues to be easily wiped away from the surface of the LiPON electrolyte film with the assistance of a dust-free cloth, resulting in the rapid recycling of the underlying LCO/LiPON film. Structural and surface characterization results indicate that the obtained LCO/LiPON which was part of the failed F-TFB remains in a good conditionwithout structural degradation, which enables its direct reuse in fabricating new TFBs. Consequently, a recycled LCO/LiPON/Li TFB (R-TFB) is constructed by sequentially depositing new LiPON and Li films on the used LCO/LiPON film, exhibiting a small interfacial resistance, recovered Li anode morphology and surface, and restorative electrochemical performance. Specifically, the R-TFB delivers a specific capacity of 0.223 mAhꞏcm −2 at 0.1 mAꞏcm −2 , acceptable rate performance (0.120 mAhꞏcm −2 at 0.8 mAꞏcm −2 ), and good cycle performance (77.3% capacity retention after 500 cycles), which are very close to those of a newly fabricated TFB, demonstrating the feasibility of this direct recycling approach. Such a simple yet efficient recycling approach may effectively extend the lifespan of solid-state batteries and provide important insights to develop sustainable TFBs for microelectronic devices.

Recent progress and perspectives on metal–organic frameworks as solid-state electrolytes for lithium batteries

“…To alleviate the abovementioned issues, the use of solid state electrolytes (SSEs) has been recognized as a good strategy, which can substitute the current liquid electrolyte and be implemented in lithium batteries. 7–9 The most widely studied SSEs include polymer solid-state electrolytes (PSEs), inorganic solid-state electrolytes (ISEs) or their hybrids. Organic polymers, such as poly(ethylene oxide) (PEO), polymethyl methacrylate (PMMA) and poly(vinylidene) fluoride (PVDF), were studied, but they present a lower ionic conductivity.…”

Constructing a robust artificial solid electrolyte interphase with a metal–organic framework for a stable Li metal anode

“…The increasing reliance on and demand for consumable electronics, electric vehicles, and smart grid storage have heightened the necessity for high energy density batteries. 1–3 While the current lithium-ion batteries with graphite anodes are approaching their theoretical limit, 4–6 lithium metal is regarded as the “holy grail” of high energy density battery anode materials due to its unparalleled specific capacity (3860 mA h g −1 ) and low redox potential (−3.04 V vs. SHE). 7–11 Furthermore, utilizing a lithium metal anode (LMA) expands the range of applicable cathode materials from lithium-rich layered cathodes (such as LiFePO 4 , LiCoO 2 , and LiNi x Co y Mn 1− x − y O 2 ) to lithium-free conversion cathodes (such as sulfur and air), enabling different types of lithium batteries.…”