Study And Failure Analysis Of High Power And High Safety Na-Ion Batteries

In recent years,Li-ion batteries(LIBs)had ushered in the peak of their industry and application development,had been widely used in various fields of human life,and their production scale is still expanding,which will inevitably lead to the great consumption of lithium resources and the price rise.If LIBs are applied to the energy storage market,the situation is bound to be even more serious.At the same time,after30 years of development,the technology development and cost reduction trend of LIBs had reached a certain bottleneck period,and the space for development is relatively limited.Therefore,it is necessary to look for alternative or alternative energy storage technology in the post-LIBs era.In this context,high safety Na-ion batteries(NIBs),which have similar working principles with LIBs and are the most economical products,will be an important supplement or even a substitute for LIBs.Now the NIBs are also about to usher in their industrialization.However,as a new chemical power supply system,the industrialization of NIBs still face some problems.Cost is their advantage,but it is not enough to depend on cost alone.It is also necessary to avoid their existing technical shortcomings and give full play to and excavate their unique performance advantages.In addition,in the process of research,manufacturing,marketing and practical application of NIBs products,it is necessary to have a certain ability to prevent the failure of products and countermeasures after the failure.For the safety,especially the study of thermal stability is the key to determine whether NIBs can be applied in large-scale industrialization and market.Based on the above background,the content of this paper will mainly revolve around looking for NIBs at high power,the unique advantages of wide working temperature range,etc,and studies their failure in performance and thermal stability.The cost evolution trend and cost reduction path of NIBs in the future were analyzed by establishing cost model from the point of view of scale manufacturing.This paper includes the following four parts:(1)In view of the high power characteristics of NIBs,we studied the performance of the battery based on O3 Cu-based layered oxide cathode(CFM)and hard carbon anode(HNA)from the aspects of the selection of battery structure and the battery design.For the first time,we have achieved the performance of rapid and continuous charging at 5C?10C rate and rapid and continuous discharging at10C?15C rate,reaching the super high power density of 2051 W/L.And these NIBs can meet-40? ? 80? of wide working temperature range,and reach the life of more than 2500 cycles at 5C/5C rate,more than the cycle and rate performance of the same specifications lithium iron phosphate batteries.having the requirement of industrialization.We have actually verified the unique performance and competitive advantage of NIBs in terms of high power,wide temperature and so on,and their comprehensive technical indicators have reached the international leading level.(2)Based on the scope and depth of current research on NIBs,the failure analysis of NIBs was focused on cycle failure by further simplifying the failure mode of NIBs.The cycle failure factors of high power NIBs based on CFM and HNA mainly include battery polarization,destruction of a cathode structure,active sodium loss and SEI loss of anode.By optimizing the failure point,the cycle life of the high power NIBs at 2C/2C rate reached 4729 cycles,showing a good cycle stability.At the same time,it is helpful to understand the failure mechanism of NIBs,and can further provide feedback and guidance to improve the material technology,optimize the battery design and manufacturing process,establish the failure mode database of NIBs,and give reasonable prevention strategies.(3)The thermal stability of the NIBs was analyzed by the thermal analysis model of the high power NIBs.The results show that NIBs have higher decomposition initial temperature(?110 °C)and lower maximum thermal runaway temperature(?350°C)than LIBs,exhibiting a favorable thermal stability.However,the heat generation of cathode accounts for a large proportion of the total heat generation,while the thermal stability of the anode determines the initial thermal runaway temperature,which is consistent with that of the LIBs.In addition,thermo gravimetric analysis(TGA)coupled with mass spectrometry(MS)experiments show that the full charged state of CFM will not release oxygen below 410°C,which is close to the lithium iron phosphate materials.The whole temperature characteristics of the NIBs in the range of-60°C?1000°C are summarized,which provides guidance for the safety design and application of the NIBs.(4)We use high power NIBs as the research object and establish a cost accounting model of NIBs by referring to and learning from the mature industrial chain of LIBs.The unit costs of NIBs composed of five cathode materials and three cathode materials with commercial prospects are calculated and compared,which provides a reference for the formation of mainstream NIBs in terms of cost performance.The cost evolution trend of the NIBs in the future is predicted and the direction of efforts to reduce the cost is illustrated,which provides some reference for the development and improvement of the NIBs technology in the future.