【Applied Energy最新原创论文】通过充电方法优化解决碱性锌钴二次电池中的自放电问题



Optimizing the charging protocol to address the self-discharge issues in rechargeable alkaline Zn-Co batteries




• The self-discharge performance of a Zn-Co battery is investigated systematically.

•A new charging protocol is proposed to increase the amount of high valence state.

• The discharge capacity is improved from 220 to 290 mAh/g owing to activation.

• The capacity retention ratio after 10h delay lifts from 72% to 90%.

水系锌钴二次电池具有内在的安全性和优异的电化学性能,而且金属锌价格低廉,储量丰富。然而,自放电问题却经常被忽略,严重影响了实际应用。本文首次系统地研究了其自放电性能,并深入分析了充电-放电机制。基于一体化四氧化三钴(Co3O4)电极,在传统的恒流充电过程中,我们发现活性材料利用率的不足。此外,开路电压在延迟期间表现出急剧的衰减,导致了较低的容量保持率。通过电化学测试和原位表征,有限的容量利用率和严重的自放电行为分别归因于较少的高价态含量和较差的稳定性。为了抑制自放电行为,我们提出了一种新型充电机制,即在恒流充电过程之后使用一定时长的恒电位充电。使用这种策略,放电容量从220 mAh/g增加到290 mAh/g,增加了约31.8%;开路搁置10小时后,容量保持率从72%提升到90%。更重要的是,即使在2500次循环之后,放电容量仍可以100%维持。这项工作为锌钴电池的运行提出了一种实用的方法,解决了应用中的限制性问题,并极大促进了这项技术的改进。此外,该成果还对其他锌基二次电池的研究提供了重要参考。

更多关于Zn-Co batteries的研究请见:



Aqueous rechargeable Zn-Co batteries feature intrinsic safety and excellent electrochemical performance, and zinc metal is cheap with abundant reserves. However, a key issue, self-discharge, which may be fatal to the application, is always overlooked. Herein, the self-discharge performance is investigated systematically for the first time, and in-depth charge-discharge mechanisms are analyzed. Based on a free-standing Co3O4 electrode, the insufficient utilization of the active material is found under a conventional galvanostatic charging process. Additionally, a dramatic attenuation in the open-circuit voltage is exhibited during the delay, leading to poor capacity retention. Through electrochemical tests and ex-situ characterization, the limited capacity and the severe self-discharge behavior are ascribed to the low amount and poor stability of the high valence state, respectively. Aiming at suppressing the self-discharge behavior, a novel charging protocol is proposed based on a new mechanism, which uses a time-controlling potentiostatic charging after the galvanostatic charging process. Using this strategy, the discharge capacity increases effectively by about 31.8% from 220 to 290 mAh/g, and the capacity retention ratio after 10 h delay lifts from 72% to 90%. More importantly, the discharge capacity remains 100% after even 2500 cycles. This work puts forward a practical method for the operation of Zn-Co batteries, addresses the limiting issues for application, and greatly facilitates the improvement of this technology. Further, the results also inspire the research of other rechargeable Zn-based batteries.


Zn-Co batteries

Charging protocol

High capacity

Low self-discharge rate

Fig.1. Graphical Abstract

Fig.2. (a) SEM images and (b) TEM images of Co3O4, and the insets show the high-magnification images. (c) CV curves of Co3O4 at various rates and (d) the corresponding fitted b-values at different redox peaks. (e) CV curve of Co3O4 at 1 mV/s and the corresponding pseudocapacitive contribution (shaded area). (f) Normalized contribution proportions of capacitance and diffusion at various scan rates. 

Fig.3. (a) The voltage variation after charging to different voltages during the delay for 10 h and (b) the corresponding discharge capacities (left: pristine; right: after the delay). (c) Voltage-time curve and the selected points for test and (d) the corresponding Co 2p XPS spectra. 

Fig.4. The battery performance under the potentiostatic charging protocol: (a) The voltage variations using different potentiostatic charging time during 10 h delay. (b) The discharge curves before and after potentiostatic charging. (c) The Co 2p XPS spectra after 6 h potentiostatic charging and after charging. (d) The corresponding discharge capacities (left: pristine; right: after delay). The capacity retention ratios during cycles after potenti

Fig.5. The capacity retention ratios during 2500 cycles for the Zn-Co battery with 10 min potentiostatic charging and pristine one.

(来源: AEii国际应用能源