Modification Of Carbon Cloth And Its Performance As A 3D Current Collector

With the rapid progress of technology,the demand for portable electronic devices,electric vehicles and other power storage devices is constantly increasing.As a result,lithium-ion batteries have been widely used in the commercial electronic field,However,due to their own high activity and lack of a host,they still have a limited lifespan and low energy in practical applications.Lithium metal has long been considered the ideal negative electrode for batteries due to its low density and high theoretical specific capacity in comparison to conventional graphite anodes.It can not only store more energy but also provide longer use time for electronic products.Therefore,new batteries based on lithium metal anodes have received widespread attention.Although lithium metal batteries have many advantages,their application in rechargeable batteries is limited by many factors,such as the growth of dendrites during cycling,the rupture of SEI,and volume expansion,which will lead to low Coulombic efficiency and short battery life.Therefore,many researchers have proposed enormous solutions such as electrode design,electrolyte engineering,solid electrolytes,the introduction of protective layers,etc.In particular,people have noticed the great potential of 3D-structured electrode materials.The cycle’s volume growth can be reduced by the three-dimensional structure’s large active specific surface area.Numerous lithium-philic sites are present in the modified 3D structure,which can enhance the quick transport of lithium ions,cause lithium metal nucleation,and control the behavior of metal deposition.The battery can achieve a long-term cycle even at high local current densities.In this experiment,a 3D material（Carbon Cloth,CC）with light weight and good conductivity was selected as the substrate.Although the 3D structure of carbon cloth can alleviate the volume expansion of lithium metal during cycling,the poor lithium affinity of carbon cloth leads to the unsatisfactory performance of the battery.Based on the above background research,the main research contents of this paper are as follows:First,carbon cloth was used as a 3D collector structure,and bismuth oxide modified carbon cloth（Bi₂O₃@CC）was obtained by stirring and high temperature sintering.In order to verify the synthesis of bismuth oxide and the practicability of the prepared anode material,material analysis and battery cycle performance tests were performed.It was found that the modified carbon cloth can use its three-dimensional structure to store lithium and alleviate the problem of volume expansion during cycling;at the same time,it can use the pro-lithium property of bismuth oxide to induce the uniform deposition of lithium metal and thus reduce the growth of dendrites.The half-cell of Bi₂O₃@CC can cycle more than 2000 cycles at a current density of 2 m A cm-²and has a very small polarization voltage during the cycle.In addition,the full battery also shows excellent performance.At the same time,the deposition and growth process of lithium metal was observed by ex-situ scanning electron microscopy.It can be seen that the structure can effectively inhibit the growth of dendrites and induce the uniform deposition of lithium metal to improve the performance of the battery.Secondly,using Carbon cloth as a 3D fluid collection structure,cobalt phosphide modified carbon cloth（Co P@CC）was prepared by stirring and high-temperature sintering methods.Theoretical calculations show that Li⁺is more easily adsorbed on the surface of Co P crystals,which can reduce the nucleation potential barrier.The well-distributed Co P provides uniform lithium nucleation sites,which can be applied in a battery system with a current density of 1 m A cm^-2 capacity of 1 m Ah cm^-2 to achieve ultra-long cycles of more than 2000 h.The Coulomb efficiency test of Co P@CC shows that the Coulomb efficiency remains above 99%after 1000 cycles,and the long cycle life of Co P@CC is not only in half-cells,but also in full cells with N/P（Negative to Positive Capacity Ratio）ratio of 1.7,which can reach 500 hours with 90%capacity retention.