锂负极失效的全固态薄膜锂电池的直接回收再利用

作为微电子器件的理想电源，全固态薄膜锂电池(TFB)已经被广泛地研究了几十年，并开始进入商业化应用。然而，目前关于失效TFB的回收与再利用的研究几乎没有，这将会阻碍TFB的可持续发展。本工作针对因金属锂负极失效而造成电池失效的TFB，提出了一种简单的基于最常见LiCoO₂ (LCO)/LiPON/Li TFB (F-TFB)的直接回收再利用的方法。研究发现，F-TFB中的金属锂负极薄膜在循环过程会被部分氧化从而造成电池失效。我们提出利用无水乙醇溶液有效地溶解并去除F-TFB上失效的金属锂负极部分，从而快速地回收底层的LCO/LiPON薄膜。结构分析和表面分析结果表明，回收的LCO/LiPON薄膜中的LCO正极的晶体结构、LCO/LiPON的界面结构以及LiPON电解质的表面保持完好，使其再利用成为了可能。进一步地，我们在回收的LCO/LiPON薄膜上依次沉积了LiPON和Li薄膜，构建得到了电化学性能恢复的LCO/LiPON/Li TFB，并获得了与新制备的TFB相一致的比容量(0.223 mAh∙cm⁻²)、良好的倍率性能和循环寿命(500次循环后容量保持率为77.3%)。这种简单而有效的回收再利用方法有望延长固态电池的使用寿命，减少能源和资源消耗，促进固态电池的可持续发展。

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

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 condition without 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 mAh·cm⁻² at 0.1 mA·cm⁻², acceptable rate performance (0.120 mAh·cm⁻² at 0.8 mA·cm⁻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.