Surface Design For Dendrite Free Lithium Metal Anode

for energy are sharply increasing,making traditional fossil energy sources unable to fully meet the desire of building a high-efficiency,sustainable,and environment-friendly society.Additionally,portable devices and mobile vehicles place ever-increasing demands on the smartness and lightness of energy devices.Thus,developing new electrochemical energy storage devices with high efficiency and high energy density is of great research significance.Compared with other rechargeable batteries,lithium metal anode with inherent high theoretical capacity(3850 mAh g-1)and low reduction potential(-3.04 V vs.SHE)is expected to produce lightweight,high-energy-density secondary batteries when being paired with various inexpensive cathode materials such as sulfur.However,enabled by the uneven ion distribution,the uncontrolled dendrite growth during cycling not only affects the stability of electrode interphase and cause "dead Li",resulting in a loss of capacity,but also displays great concern of piecing the separator and causing safety problems like short circuit and firing.Therefore,it is necessary for researchers to regulate lithium deposition and develop dendrite-free lithium metal anode before taking lithium metal anode into practical consideration.In this regard,this thesis focuses on the regulation of lithium deposition behaviour by the rational design of surface protective layer.Two kinds of strategies are mainly involved:1.An LiCl-rich organic-inorganic hybrid protective layer(OIHL)was prepared by dehalogenation and polymerization of perchorolythene,taking full use of the natural alkaline oxide layer on lithium anode surface.According to the experiment,this hybrid layer improved the interface stability of lithium metal electrode and inhibited dendrite growth effectively.Li symmetric cells with OIHL maintained low overpotential of 20 mV at a current density of 1 mA m-2 after cycling over 3000 h,indicating the improvement of cycling performance.2.The LiAl-LDH material was introduced as the artificial interphase for lithium metal anode.We regulated the lithium ions transfer pathway via lithium vacancy in the layers of LiAl-LDH for stable lithium desposition.The results of NMR and electrochemical characterization demonstrated the existence of lithium vacancy and its strong absorption ability toward lithium ions.Meanwhile,the rapid lithium pathway contributed to a good performance at high current density and rate.The Li ? LFP full cells maintained 88%capacity after 300 cycles at 10.0 C.In this paper,lithium deposition is regulated from the perspective of surface protection,emphasizing the importance of interfacial mass transfer when inhibiting dendrite growth.The homogeneous and rapid lithium-ion pathway at the interphase will favourably promote uniform lithium deposition.This work provides new ideas for dendrite inhibition by lithium metal anode surface protection.