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隨著科技發(fā)展，人類對能源的需求與日俱增，而目前商業(yè)化的鋰離子電池（理論容量372mAh/g）已不能滿足該需求，高容量密度電池的開發(fā)已成為研究熱點(diǎn)。鋰金屬具有高理論比容量（3860mAh/g），在儲能領(lǐng)域有很大應(yīng)用潛力。然而鋰枝晶的生長，不僅降低了電池性能，而且容易發(fā)生短路，造成安全隱患。這些問題嚴(yán)重阻礙了鋰金屬電池的發(fā)展和實(shí)際應(yīng)用。

為解決上述問題，科學(xué)家們提出了各種方案，如制備三維嵌鋰基體、鋰金屬表面包覆、隔膜改性等。但這些方式增加了電池整體重量，且制備過程繁瑣，不利于商業(yè)化生產(chǎn)。最近，Qian等通過對比不同電解液環(huán)境對鋰枝晶生長的影響，提出高濃度LiFSI醚類電解液環(huán)境下，即使沒有嵌鋰基體，仍可有效抑制鋰枝晶在銅集流體上的生長，同時，電池庫倫效率也有顯著提高。

Figure 1. Schematicillustrations of battery configurations. a) State-of-the-art Li-ion battery,i.e., Cu|C₆||LiFePO₄|Al. b) Anode-free battery,i.e.,Cu||LiFePO₄|Al.

   實(shí)驗(yàn)以Cu-LiFePO₄電池為研究體系，分別選用1 M LiPF₆-EC/DMC(1/2 v/v)酯類電解液和4 MLiFSI-DME醚類電解液進(jìn)行對比。實(shí)驗(yàn)結(jié)果表明隨著循環(huán)次數(shù)增加，酯類電解液環(huán)境下電池電阻增加明顯，而4 MLiFSI-DME醚類電解液環(huán)境下，電阻增幅較小。而且在4 MLiFSI-DME環(huán)境下，多次循環(huán)后平均庫倫效率大于99%。即使在2 mA cm^-2電流密度下，庫倫效率仍接近100%。另外，該研究發(fā)現(xiàn)通過調(diào)節(jié)測試條件，也可提高庫倫效率。當(dāng)鋰以0.2 mA cm^-2沉積，2mA cm^-2脫出時，平均庫倫效率可達(dá)99.6%，高于一直以0.2 mA cm^-2/2mAcm^-2進(jìn)行循環(huán)的庫倫效率。

Figure 2. Nyquistplot of anode-free Cu||LiFePO₄ cells with either 1 M LiPF₆-EC/DMC(dashed line) or 4 M LiFSI-DME (solid line) after differentcycles whencharged/discharged at 0.2 mA cm^?2. All data were collectedatdischarged state of the cells.

Figure 3. Electrochemical performance of anode-freeCu||LiFePO₄ cells with either 1 M LiPF₆-EC/DMC or 4 M LiFSI-DME.a) Charge/discharge voltageprofiles for the first three cycles with the twoelectrolytes. b) Capacity retention and CE of the cells with the twoelectrolytes as a function of cycle numberwhen charged/discharged at 0.2 mA cm^?2(open symbols: charge capacity, filled symbols:discharge capacity). c) Capacityretention of the cells with 4 M LiFSI-DME charged/discharged at differentcurrent densities.

Figure 4. Cycling performance of Cu||Li and Cu||LiFePO₄cells with 4 M LiFSI-DME cycled at different current densities. a) Li||LiFePO₄cell cycled withlow-rate (C/5) charging and high-rate (2 C) discharging. b) CEof Cu||Li cells. A capacity of 0.5 mAh cm^?2 was used to plate the Limetal, which wassubsequently stripped by cycling to 1.0 V versus Li/Li .c) Charge/discharge voltage profiles for the first 30 cycles of the anode-freecells (Cu||LiFePO₄)with 4 MLiFSI-DME cycled at different currentdensities. d) Discharge capacity and CE of anode-free Cu||LiFePO₄cells charged at 0.2 mA cm^?2 anddischarged at either 0.2 or 2.0 mAcm^?2 (open symbols: charge capacity, filled symbols: dischargecapacity).

綜上，該工作提出了一種可有效抑制鋰枝晶生長的電解質(zhì)，并通過表征解釋其原因，對鋰金屬電池的研究和大規(guī)模生產(chǎn)具有指導(dǎo)意義。

相關(guān)研究成果發(fā)表在著名刊物Advanced Functionalmaterials上（DOI：10.1002/adfm.201602353.） JiangfengQian, Brian D. Adams, Jianming Zheng,Ji-Guang Zhanget al. Anode-Free RechargeableLithium Metal Batteries.Adv. Funct. Mater. 2016.）。

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