碳酸盐型盐湖提取钾芒硝浮选工艺研究

西藏盐湖中碳酸盐型盐湖分布广泛,在蒸发过程中形成的含钾矿物以钾芒硝与氯化钾为主。以碱性碳酸盐型盐湖为研究对象,开发新捕收剂,利用浮选工艺从不同的含钾原矿中,浮选加工出品位较高的钾芒硝和氯化钾。在研究了解离度、捕收剂添加量、固液比、浮选时间、转速、充气量、精选实验等条件实验的基础上,确立了最佳闭路循环流程工艺条件。通过闭路循环实验,计算循环物料量,获得产品品位、钾离子收率等参数。实验表明,浮选工艺加工钾芒硝为主的矿物体系,钾元素收率高达98%,得到钾芒硝质量分数为91%以上的矿物。     

Juggling Formation of HF and LiF to Reduce Crossover Effects in Carbonate Electrolyte with Fluorinated Cosolvents for High-Voltage Lithium Metal Batteries

Fluorinated solvents emerge as a promising strategy to improve performance of lithium metal batteries (LMBs). However, most of them are prone to produce corrosive HF and deteriorate electrode interface, inducing cathode-to-anode detrimental crossover of transition metal-ions. Here, fluorinated aromatic hydrocarbons in dimethyl carbonate (DMC)-based diluted highly concentrated electrolyte (DHCE) are employed to juggle formation of HF and LiF, enabling stable cycling of high-voltage LiNi_0.7Co_0.1Mn_0.2O₂ (NCM712) and LiCoO₂ (LCO). The nature of aromatics in this carbonate-based DHCE makes them difficult to undergo β-hydrogen assisted defluorination, evidencing by the high energy barrier and high bond energy of β-sites hydrogen. The advanced DHCE restrains HF formation but strengthens LiF formation, which not only suppresses impedance growth, transition-metal dissolution, and stress crack on the cathode, but achieves highly reversible Li stripping/plating with an outstanding average Coulombic efficiency up to 99.3%. The Li||NCM712 cell and Li||LCO cell both exhibits superior cycling stability at high operation voltage. Even under stringent conditions, the 4.4 V Li||NCM712 full battery retains >95% of the initial capacity over 100 cycles, advancing practical high-voltage LMBs. This study designs an efficient electrolyte that generates robust electrode/electrolyte interphases and restrains by-products formation spontaneously, thus shedding new light on electrolyte toward applicable LMBs.