Lithium metal anodes: Present and future

Commercial lithium-ion(Li-ion)batteries based on graphite anodes are meeting their bottlenecks that are limited energy densities.In order to satisfy the large market demands of smaller and lighter rechargeable batteries,high-capacity metallic Li replacing low-specific-capacity graphite enables the higher energy density in next-generation rechargeable Li metal batteries(LMBs).However,Li metal anode has been suffering from dendritic problems,interfacial side reactions,volume change and low Coulombic efficiency.Therefore,performance enhancements of Li metal anodes are rather important to realize the high energy density characteristic of metallic Li.In this review,the annoying Li dendrite growth,unstable reaction interface and practical application issues of Li metal anodes are summarized and detailedly discussed to understand the current challenges concerning Li metal anodes.For overcoming such remaining challenges,the corresponding strategies and recent advances are covered and categorized.Finally,we discuss future opportunities and perspectives for developing high-performance Li metal anodes.

One-time sintering process to modify xLi2MnO3(1-x)LiMO2 hollow architecture and studying their enhanced electrochemical performances

To solve the critical problems of lithium rich cathode materials, e.g., structure instability and short cycle life, we have successfully prepared a ZrO2-coated and Zr-doping xLi2MnO3·(1–x)LiMO2 hollow architecture via one-time sintering process. The modified structural materials as lithium-ion cathodes present good structural stability and superior cycle performance in LIBs. The discharge capacity of the ZrO2-coated and Zr-doped hollow pristine is 220 mAh g-1 at the 20th cycle at 0.2 C(discharge capacity loss, 2.7%)and 150 m Ah g-1 at the 100 th cycle at 1 C(discharge capacity loss, 17.7%), respectively. However, hollow pristine electrode only delivers 203 m Ah g-1 at the 20 th cycle at 0.2 C and 124 mAh g-1 at the 100 th cycle at 1 C, respectively, and the corresponding to capacity retention is 92.2% and 72.8%, respectively.Diffusion coefficients of modified hollow pristine electrode are much higher than that of hollow pristine electrode after 100 cycles(approach to 1.4 times). In addition, we simulate the adsorption reaction of HF on the surface of ZrO2-coated layer by the first-principles theory. The calculations prove that the adsorption energy of HF on the surface of ZrO2-coated layer is about-1.699 e V, and the ZrO2-coated layer could protect the hollow spherical xLi2MnO3·(1–x)LiMO2 from erosion by HF. Our results would be applicable for systematic amelioration of high-performance lithium rich material for anode with the respect of practical application.

Facile and scalable fabrication of lithiophilic Cu_(x)O enables stable lithium metal anode

Equipped with highest-energy density anode,lithium metal batteries are of great interests for the nextgeneration energy storage systems.However,the existing problems like uneven Li deposition,large volume expansion and short cycling lifespan severely retard the implementation of Li metal anodes.Herein,we report an in-situ formed Cu_(x)O nanofiber network synthesized by facile and scalable calcination process and employ as stable lithium metal anode.The CuO/Cu_(2)O ratio in the lithiophilic Cu_(x)O network can be adjusted through an optimal annealing time,thus guiding the homogeneous distribution of Li atoms and regulating the repeated plating/stripping processes.As a result,Li@Cu_(x)O 3D scaffold displays an ultralow overpotential of 7.7 mV,long cycling life for more than 1000 h in symmetric cell,and exceptional stability for LiFePO_(4)//Li full cells.This work provides guidelines for the design and fabrication of lithiophilic 3D matrixes and advances the practical use of lithium metal batteries.

利用可拉伸微脑皮层电极定位癫痫病灶并评估电刺激对大鼠癫痫发作的影响

癫痫是一种慢性神经系统疾病,其发病率在全球范围内不断上升,但由于缺乏有效的工具来监测和调节相关的脑神经活动,癫痫病灶的准确定位和相应的治疗仍然具有挑战性.在这项工作中,我们开发了可拉伸微脑皮层(mECoG)电极,并用于研究青霉素诱导的大鼠癫痫发作.该电极具有良好的延展性、共形性、抗干扰能力和高分辨率,能够成功地监测脑电信号,并优于传统的刚性聚酰亚胺电极.通过检测和分析特征性癫痫棘波,我们研究了癫痫发作期间的癫痫灶和电刺激效应.研究发现,棘波首先出现在视皮层,很可能是癫痫的病灶.癫痫发作后棘波频率迅速增加至1.07 Hz,达到平台并保持稳定.没有一个大脑半球可以显示癫痫发作的早期预警.青霉素诱导后,我们施加了不同时长的电刺激.研究发现,15分钟的电刺激对癫痫发作的抑制效果最好.本研究开发的mECoG电极在可拉伸生物医学器件中具有应用前景.