以钠金属为对电极的纽扣半电池通常被用来评价钠离子电池电极材料的电化学性能。本工作揭示了在低温环境下,钠金属半电池在商业化酯类电解液中用于评价电极材料电化学性能存在局限性,这是因为钠金属电极在低温下具有高界面和电荷转移电...以钠金属为对电极的纽扣半电池通常被用来评价钠离子电池电极材料的电化学性能。本工作揭示了在低温环境下,钠金属半电池在商业化酯类电解液中用于评价电极材料电化学性能存在局限性,这是因为钠金属电极在低温下具有高界面和电荷转移电阻导致了大的Na+的沉积/剥离过电势,干扰了半电池对电极材料低温电化学性能的评价。Na||硬碳(HC)半电池在-20℃以0.2C (1C=300 m A/g)的倍率充放电时,钠金属电极的电位变化高达0.94 V,HC电极材料仅表现出21.1 m Ah/g比容量,存在对HC低温电化学性能不准确评价的可能性。针对此,本文提出了一种可以取代钠金属的Na15Sn4@Na复合电极用于钠离子电池电极材料的低温电化学性能评价。研究表明,Na15Sn4@Na电极有着与钠金属相同的电极电位。在-20℃的低温工况下,Na15Sn4@Na||Na15Sn4@Na对电池在0.1 m A/cm^(2)电流密度下的沉积/剥离过电势仅为0.09 V,远远小于钠金属电极0.96 V的沉积/剥离过电势。使用HC作为研究对象,所制备的Na15Sn4@Na||HC半电池在-20℃下,在HC析钠前,展现出高达100.8 m Ah/g的比容量,远高于以钠金属为对电极的半电池所展示的比容量(21.1 m Ah/g),说明基于Na15Sn4@Na对电极的半电池更能准确地表征材料本征的低温电化学性能。该工作为钠离子电池电极材料低温电化学性能的准确评价提供了实验依据。展开更多
Electrolytic aqueous zinc-manganese(Zn–Mn) batteries have the advantage of high discharge voltage and high capacity due to two-electron reactions. However, the pitfall of electrolytic Zn–Mn batteries is the sluggish...Electrolytic aqueous zinc-manganese(Zn–Mn) batteries have the advantage of high discharge voltage and high capacity due to two-electron reactions. However, the pitfall of electrolytic Zn–Mn batteries is the sluggish deposition reaction kinetics of manganese oxide during the charge process and short cycle life. We show that, incorporating ZnO electrolyte additive can form a neutral and highly viscous gel-like electrolyte and render a new form of electrolytic Zn–Mn batteries with significantly improved charging capabilities. Specifically, the ZnO gel-like electrolyte activates the zinc sulfate hydroxide hydrate assisted Mn^(2+) deposition reaction and induces phase and structure change of the deposited manganese oxide(Zn_(2)Mn_(3)O_8·H_(2)O nanorods array), resulting in a significant enhancement of the charge capability and discharge efficiency. The charge capacity increases to 2.5 mAh cm^(-2) after 1 h constant-voltage charging at 2.0 V vs. Zn/Zn^(2+), and the capacity can retain for up to 2000 cycles with negligible attenuation. This research lays the foundation for the advancement of electrolytic Zn–Mn batteries with enhanced charging capability.展开更多
文摘以钠金属为对电极的纽扣半电池通常被用来评价钠离子电池电极材料的电化学性能。本工作揭示了在低温环境下,钠金属半电池在商业化酯类电解液中用于评价电极材料电化学性能存在局限性,这是因为钠金属电极在低温下具有高界面和电荷转移电阻导致了大的Na+的沉积/剥离过电势,干扰了半电池对电极材料低温电化学性能的评价。Na||硬碳(HC)半电池在-20℃以0.2C (1C=300 m A/g)的倍率充放电时,钠金属电极的电位变化高达0.94 V,HC电极材料仅表现出21.1 m Ah/g比容量,存在对HC低温电化学性能不准确评价的可能性。针对此,本文提出了一种可以取代钠金属的Na15Sn4@Na复合电极用于钠离子电池电极材料的低温电化学性能评价。研究表明,Na15Sn4@Na电极有着与钠金属相同的电极电位。在-20℃的低温工况下,Na15Sn4@Na||Na15Sn4@Na对电池在0.1 m A/cm^(2)电流密度下的沉积/剥离过电势仅为0.09 V,远远小于钠金属电极0.96 V的沉积/剥离过电势。使用HC作为研究对象,所制备的Na15Sn4@Na||HC半电池在-20℃下,在HC析钠前,展现出高达100.8 m Ah/g的比容量,远高于以钠金属为对电极的半电池所展示的比容量(21.1 m Ah/g),说明基于Na15Sn4@Na对电极的半电池更能准确地表征材料本征的低温电化学性能。该工作为钠离子电池电极材料低温电化学性能的准确评价提供了实验依据。
基金financially supported by National Natural Science Foundation of China (22209133, 22272131, 21972111, 22211540712)Natural Science Foundation of Chongqing (CSTB2022NSCQ-MSX1411)+1 种基金Chongqing Engineering Research Center for Micro-Nano Biomedical Materials and DevicesChongqing Key Laboratory for Advanced Materials and Technologies。
文摘Electrolytic aqueous zinc-manganese(Zn–Mn) batteries have the advantage of high discharge voltage and high capacity due to two-electron reactions. However, the pitfall of electrolytic Zn–Mn batteries is the sluggish deposition reaction kinetics of manganese oxide during the charge process and short cycle life. We show that, incorporating ZnO electrolyte additive can form a neutral and highly viscous gel-like electrolyte and render a new form of electrolytic Zn–Mn batteries with significantly improved charging capabilities. Specifically, the ZnO gel-like electrolyte activates the zinc sulfate hydroxide hydrate assisted Mn^(2+) deposition reaction and induces phase and structure change of the deposited manganese oxide(Zn_(2)Mn_(3)O_8·H_(2)O nanorods array), resulting in a significant enhancement of the charge capability and discharge efficiency. The charge capacity increases to 2.5 mAh cm^(-2) after 1 h constant-voltage charging at 2.0 V vs. Zn/Zn^(2+), and the capacity can retain for up to 2000 cycles with negligible attenuation. This research lays the foundation for the advancement of electrolytic Zn–Mn batteries with enhanced charging capability.
