Abstract Leaching of active cathode materials of Li-ion batteries (LIB) is a hotly contested topic. In the published literature, the best processes utilize concentrated acid (e.g. 2–3 M H2SO4) and elevated temperatures for waste LIB leaching, along with unstable reduction reagents such as H2O2. In this study, we demonstrate the dissolution of LiCoO2 (LCO) in a low-acid leaching system that utilizes typical battery elements which can be found in impure, recycled black masses; Fe2+ as a reducing agent towards LCO, and Cu as a reducing agent towards Fe3+. We show for the first time that the Cu-Fe2+-H2SO4 system can provide an excellent performance in dissolving LCO materials at low acid environment and near-room temperature (T = 30 °C), even to the point where the acidity of the solution decreases to pH = 1.89 while reaching Co extraction of 92%. To the best of our knowledge, such high leaching efficiency has not been previously reported under such mild conditions. Nowadays, recyclability of the process waters may also be important, and herein we highlighted the influence of Na2SO4 on leaching of LCO active materials as well in this system. Minimization of the lixiviant concentration and temperature is beneficial in allowing decrease in chemical and energy consumption. High pH operation also can support further downstream processing, helping to avoid the problem of sodium accumulation towards the end-stage where lithium is recovered.

中文翻译：

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Fe催化Cu-H2SO4体系中锂离子电池活性材料的低酸浸出

摘要 锂离子电池（LIB）正极活性材料的浸出是一个热门话题。在已发表的文献中，最好的工艺利用浓酸（例如 2-3 M H2SO4）和高温进行废 LIB 浸出，以及不稳定的还原剂，例如 H2O2。在本研究中，我们展示了 LiCoO2 (LCO) 在低酸浸出系统中的溶解，该系统利用可在不纯的回收黑色物质中找到的典型电池元件；Fe2+ 作为 LCO 的还原剂，Cu 作为 Fe3+ 的还原剂。我们首次表明，Cu-Fe2+-H2SO4 系统可以在低酸性环境和接近室温（T = 30 °C）下提供优异的溶解 LCO 材料的性能，甚至可以达到溶液的酸性降低到 pH = 1.89，同时达到 92% 的 Co 提取。据我们所知，在如此温和的条件下，以前从未报道过如此高的浸出效率。如今，工艺用水的可回收性也可能很重要，在此我们强调了 Na2SO4 对 LCO 活性材料在该系统中的浸出的影响。最小化浸出剂浓度和温度有利于减少化学品和能源消耗。高 pH 值操作还可以支持进一步的下游加工，有助于避免钠在回收锂的最后阶段的问题。在此我们强调了 Na2SO4 对 LCO 活性材料浸出的影响以及该系统中。最小化浸出剂浓度和温度有利于减少化学品和能源消耗。高 pH 值操作还可以支持进一步的下游加工，有助于避免钠在回收锂的最后阶段的问题。在此我们强调了 Na2SO4 对 LCO 活性材料浸出的影响以及该系统中。最小化浸出剂浓度和温度有利于减少化学品和能源消耗。高 pH 值操作还可以支持进一步的下游加工，有助于避免钠在回收锂的最后阶段的问题。