With the rapid development of nanomaterial technology and advanced characterization methods, lithium-ion secondary batteries with high energy density have once again received the attention of researchers with extensive research. However, dendritic lithium metal deposition, accumulated electrochemically deactivated lithium, low coulombic efficiency, and short circuit of the battery have always plagued the practical application of lithium metal batteries. Numerous studies have shown that improving the mechanical strength of the battery separator and artificial electrolyte interface film can effectively inhibit the growth of lithium dendrites, but the conventional two-dimensional modified interface is difficult to cope with large electrode volume changes during deep charge and discharge (3 mAh cm− 2, 15μm). The composite lithium metal anode supported by the three-dimensional skeleton can effectively limit the deposition of lithium metal in the frame. At this time, the skeleton itself is the only physical barrier to the deposition of uneven lithium metal, so it is necessary to optimize the mechanical strength of the three-dimensional frame.
Recently, the Lu Yingying Group of the School of Chemical Engineering of Zhejiang University and the Tong Zheming Group of the School of Mechanical Engineering have constructed a nano-diamond/lithium metal composite anode by a simple thermal fusion method. The nano-diamond framework has an ultra-high Young's modulus and can be used in high-surface capacity. Lithium metal deposition during the electrochemical cycle is effective and small electrode volume changes. Because of the ultra-high Young's modulus of nanodiamonds and the small Poisson's ratio, the uneven lithium metal is deformed and confined within the porous nanodiamond framework. The simulation results based on finite element analysis also show that the nano-diamond matrix with ultra-high modulus can cause mechanical deformation of uneven lithium deposition and stabilize lithium metal deposition. At a current density of 1 mA cm-2, a symmetric battery composed of a nano-diamond/lithium composite anode can be stably cycled for 1400 hours, even at a large current density of 10 mA cm-2, the overpotential of lithium metal stripping/deposition is only It is 60 mV. The composite negative electrode is matched with the sulfur positive electrode and maintains 607.3 mAh g−1 after 500 cycles at 1 C rate.
The related results were published in Small Methods (DOI: 10.1002/smtd.201900325). Zhang Weidong and Fan Lei, graduate students of Zhejiang University, were the first authors of the paper. The authors were Tong Zheming and Lu Yingying of Zhejiang University.
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