Li/CF_(x)一次电池研究进展

Research progress of Li/CF_(x) primary batteries

锂/氟化碳(Li/CF_(x))一次电池是目前能量密度最高的化学电源,具有输出电压稳定、安全性好、使用温度范围宽和自放电率低等特点,在军事(单兵作战系统)、医疗(心脏起搏器)、太空探索(空间站)等关键领域具有无可替代的重要性。然而,氟化碳材料的电子导电性较差,很大程度地影响了电化学反应的电极过程动力学,导致Li/CF_(x)一次电池存在高倍率放电性能差、初始放电电压延迟严重、放电过程中发热量大等问题。本文通过对近期相关文献的探讨,首先综述了Li/CF_(x)一次电池在放电机理方面的研究进展,包括两相放电反应机理模型、生成石墨层间化合物中间相的放电反应机理模型、“核-壳”模型反应机理和边缘传播放电反应机理以及最近刚被提出的三步放电反应机理等。其次,重点分析了Li/CF_(x)一次电池面临问题的解决方法,包括氟化碳材料前驱体的选择、氟化方法的改进、复合材料的构建以及电解液的改性和优化方法。其中,氟化碳纳米管、氟化富勒烯、氟化石墨烯等新型氟化碳基材料的应用为氟化碳的发展提供了新的前景。在复合材料的构建策略上,导电聚合物、金属纳米颗粒、氧化物的加入可显著降低电压延迟时间和提升倍率性能。在电解液的调控策略上,氟离子结合剂的引入和氟化锂晶体生长动力学的计算,对于溶解氟化锂和控制氟化锂的生长具有重要作用,有望实现兼具高能量密度和高功率密度的宽温域Li/CF_(x)一次电池。

Currently,lithium/fluorinated carbon(Li/CF_(x)) primary batteries are chemical power sources with the highest energy density and have stable output voltage,good safety,wide operating temperature range,and low self-discharge rate.These features are of irreplaceable importance in critical fields such as military(man-portable combat systems),medical(pacemakers),and space explorations(space stations).However,the poor electronic conductivity of CF_(x) largely affects the electrode process kinetics of electrochemical reactions,resulting in poor high-magnification discharge performance,severe delay in initial discharge voltage,and high heat generation during the discharge process of Li/CF_(x) primary batteries.In this paper,we first review the discharge mechanism of Li/CF_(x) primary batteries by examining the recent literature on the two-phase discharge reaction mechanism model,discharge reaction mechanism model for the generation of graphite interlayer compound intermediate phase,"core-shell"model reaction mechanism,edge propagation discharge reaction mechanism,and three-step discharge reaction mechanism.Second,the solutions to the problems faced in Li/CF_(x) primary batteries are analyzed by focusing on the selection of CF_(x) precursors,improvement of fluorination methods,construction of composite materials,and modification and optimization methods of electrolytes.Among them,the application of new fluorocarbonbased materials such as fluorinated carbon nanotubes,fluorinated fullerenes,and fluorinated graphene provides new prospects for the development of CF_(x).Incorporating conducting polymers,metal nanoparticles,and oxides during the construction of composite materials can significantly reduce the voltage delay time and improve the rate performance.In the regulation strategy of electrolyte,the introduction of fluorine ion binding agent and the calculation of lithium-fluoride crystal growth kinetics play an important role in dissolving and controlling the growth of lithium-fluoride,which is expected to realize a wide temperature domain Li/CF_(x) primary battery with both high energy density and high power density.