High safety composite lithium metal anode is the next generation of high energy density energy storage battery?
The research group of Professor Zhang Qiang from the Department of Chemical Engineering of Tsinghua University published the paper "Coralloid Carbon Fiber-Based Composite Lithium Anode for Robust Lithium Metal Batteries" in the well-known journal "Joule" in the energy field. Important progress has been made in the field of high-safety and high-capacity composite lithium metal anodes. The research was selected as the cover article of this issue of Joule, and the cover image was published.
Metal lithium has extremely high theoretical specific capacity and the lowest redox electrode potential, so it has become the most ideal anode material for next-generation high-energy-density energy storage batteries (next-generation solid-state lithium batteries, lithium-sulfur batteries, lithium-air batteries, etc.). However, the dendrite problem during the charging and discharging process of metal lithium and the instability of the lithium-electrolyte interface film seriously reduce the cycle efficiency of lithium metal batteries, shorten the service life of the battery, and even bring a certain degree of safety hazards. hinder the development of lithium metal batteries.
The cover picture uses a metaphor to express the design idea of "composite lithium metal negative electrode". The composite lithium metal negative electrode based on lithiophilic carbon fiber is likened to a ship, which can sail stably in the "ocean" of molten lithium.
Recently, researchers have proposed a number of metallic lithium anodes based on conductive carbon frameworks or metal frameworks. However, many of these frameworks were not pre-complexed with metallic lithium, but were tested in half-cells as lithium-free current collectors. Such lithium-free current collectors are difficult to directly apply to full cells. Therefore, how to efficiently pre-compound lithium metal into the current collector structure to form a high-performance composite lithium metal anode that can be directly assembled into a full battery has become the focus of research.
In response to the urgent demand for composite electrodes in lithium metal batteries, the research team of Professor Zhang Qiang of Tsinghua University proposed a composite lithium metal negative electrode with coral-like carbon fiber molten lithium. The surface of the carbon fiber skeleton (CF) is modified into a lithiophilic surface by the method of electroplating silver coating, so that the liquid molten lithium metal can be quickly absorbed into the carbon fiber skeleton (CF/Ag) with silver coating, so as to obtain high performance The composite lithium metal anode (CF/Ag-Li).
On the one hand, the silver coating can modify any conductive framework into a lithiophilic conductive framework that can siphon liquid molten lithium. Cyclic morphology of "dead lithium". Through the experimental observation of in-situ metallic lithium deposition, it is found that it is difficult to form dendrites in this composite structure. The proposed composite lithium metal anode can be stably cycled for more than 160 cycles with very low polarization under extremely harsh conditions of 10 mAcm-2 and 10 mAhcm-2. Compared with conventional lithium metal anodes, the composite lithium metal anode can withstand extreme areal current density and areal capacity cycling, showing high safety features.
Coral-like carbon fiber molten lithium-filled composite lithium metal anode
The composite metal lithium negative electrode is directly assembled with the sulfur positive electrode and the lithium iron phosphate positive electrode to form a lithium-sulfur battery and a lithium iron phosphate battery with excellent performance. Its lithium iron phosphate battery can stably cycle for more than 500 cycles at a rate of 1.0C, while the lithium-sulfur battery has an initial discharge capacity of 781mAhg-1 at 0.5C, and maintains a high-capacity cycle for more than 400 cycles. The conductive skeleton silver-plated lithium-injection method of this work can be universally applied to the design and preparation of any composite metal lithium anode based on the conductive skeleton. Lithium" cycle appearance, and then obtain excellent electrochemical performance in full battery systems such as lithium-sulfur batteries, and improve the safety of energy storage systems.
