Liquid Polydimethylsiloxane Grafting to Enable Dendrite‐Free Li Plating for Highly Reversible Li‐Metal Batteries,Advanced Functional Materials

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Liquid Polydimethylsiloxane Grafting to Enable Dendrite‐Free Li Plating for Highly Reversible Li‐Metal Batteries
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2019-05-27 , DOI: 10.1002/adfm.201902220
Junwei Meng _{1,

2} , Fulu Chu ₁ , Jiulin Hu _{1,

2} , Chilin Li _{1,

2}

Affiliation

Li‐metal is considered as the most promising anode material to advance the development of next‐generation energy storage devices owing to its unparalleled theoretical specific capacity and extremely low redox electrochemical potential. However, safety concerns and poor cycling retention of Li‐metal batteries (LMBs) caused by uncontrolled Li dendrite growth still limit their broad application. Herein, liquid polydimethylsiloxane (PDMS) terminated by –OCH₃ groups is proposed as a graftable additive to reinforce the anode dendrite suppression for LMBs. Such a grafting triggers the formation of a conformal hybrid solid electrolyte interphase (SEI) with increased fractions of LiF and Li–Si–O‐based moieties, which serve as a rigid barrier and ionic conductor for uniform Li‐ion flow and Li‐mass deposition. The grafting protected anode endows Li/Li symmetric cells with a long lifetime over 1800 h with a much smaller voltage gap (≈25 mV) between Li plating and stripping, than the naked anode. The coulombic efficiency values for Li/Cu asymmetric cells in carbonate electrolyte can reach up to 97% even at a high current density of 3 mA cm⁻² or high capacity up to 4 mAh cm⁻². The liquid PDMS additive shows advantage over solid siloxane additives with poor grafting ability in terms of Li surface compaction and SEI stabilization.

中文翻译：

液态聚二甲基硅氧烷接枝可实现高度可逆锂金属电池的无枝晶锂电镀

由于其无与伦比的理论比容量和极低的氧化还原电化学势，锂金属被认为是推动下一代储能设备发展的最有希望的阳极材料。但是，由于锂枝晶生长不受控制而引起的安全问题和锂金属电池（LMB）的循环保持能力差，仍然限制了其广泛应用。本文中，液态聚二甲基硅氧烷（PDMS）被–OCH ₃封端有人建议将这些基团作为可接枝的添加剂来增强LMB的阳极枝晶抑制作用。这种接枝会触发共形混合固体电解质中间相（SEI）的形成，并增加LiF和Li-Si-O基部分的比例，这些部分可作为刚性屏障和离子导体，以实现均匀的Li-离子流和Li-mass沉积。与裸阳极相比，接枝保护的阳极使Li / Li对称电池具有1800 h以上的长寿命，并且在Li电镀和剥离之间的电压间隙（≈25mV）小得多。即使在3 mA cm ^-2的高电流密度或高达4 mAh cm ^-2的高容量下，碳酸盐电解质中Li / Cu不对称电池的库仑效率值也可以达到97％。就Li表面致密性和SEI稳定性而言，液态PDMS添加剂优于接枝能力差的固态硅氧烷添加剂。

更新日期：2019-05-27

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