How to assemble power deduction to achieve repeatable full battery performance?

　　The evaluation of battery materials usually starts with lithium metal as the negative electrode, so as to understand the available capacity of new materials. However, there are some problems in evaluating the cycle stability of new materials coupled with lithium metal.

　　First, the electrochemical performance of the battery is determined by the worst electrode, assuming that the electrolyte is compatible and always sufficient. If the coupling between the electrode material and the lithium anode is really "poor", the lithium metal battery will be very poor from the first cycle.

　　However, if the cathode material is good, as the cycle goes on, due to the accumulation of solid electrolyte interface phase (SEI), this greatly increases the battery impedance, leading to accelerated degradation of the battery, making it difficult to determine whether lithium anode or cathode is the main cause of battery failure.

　　Now people gradually realize that in order to develop high-energy lithium ion batteries, the load quality of electrodes needs to be appropriately high, and the porosity needs to be controlled to meet the energy target of battery level. When a high-quality loaded electrode is combined with lithium metal, the deep stripping and deposition of lithium will lead to the rapid degradation of the battery after only dozens or even several cycles, depending on the positive electrode load and the amount of electrolyte used. In addition, when Li metal is used to evaluate other electrode materials, the observed magnification performance is almost independent of the evaluated materials in actual lithium ion batteries, because Li metal is now the electrode with the worst magnification in these batteries, and determines the observed performance.

　　Graphite based all cell is a good platform for effective evaluation of electrode materials. Graphite undergoes the intercalation reaction of minimum volume expansion and forms stable SEI on its surface, allowing Li+to enter and exit its layered structure reversibly. However, up to now, little attention has been paid to the procedures for manufacturing reliable button type full batteries with parameters related to industrial adaptability. Without a reliable button battery assembly scheme, it will be challenging to evaluate new ideas or methods for studying the chemistry and electrochemistry of these materials, let alone to correlate the results with the actual battery system. This paper discusses the relationship between science and engineering in the preparation of high-quality nickel manganese cobalt (NMC) positive electrode and graphite negative electrode button type battery. More importantly, this paper did not propose a detailed scheme, but studied the key parameters affecting the performance of the whole battery from different aspects: electrode preparation, battery construction, standing time and testing. Therefore, based on the principles discussed in this work, researchers can not only easily repeat this work, but also further apply this knowledge to other button type full batteries, such as silicon and tin based batteries and ion batteries.

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