Nickel Hydride No. 5 battery

Factors affecting the fast charging ability of Nickel Hydride No. 5 battery from the perspective of battery composition structure

The factors affecting the fast charging ability of lithium-ion batteries are analyzed from the perspective of battery structure

Under different state parameters and environmental parameters, the charging current value of each lithium-ion battery is optimal. So, from the perspective of battery structure, what are the factors affecting the optimal charging value?

Microscopic charging process

Lithium-ion batteries are called rocking chair batteries, in which charged ions move between the positive and negative electrodes, ending the charge transfer and powering or charging the external circuit. In the specific charging process, the external voltage is loaded on the north and south poles of the battery, and lithium ions are detonated from the positive electrode into the electrolyte. The remaining electrons are generated together and move to the negative electrode through the positive electrode collection liquid and the external circuit. Lithium ions go from the positive electrode to the negative electrode in the electrolyte, through the gap to the negative electrode; through the SEI film on the outer surface of the anode, they are embedded in the graphite layered structure of the anode and combined with electrons.

In the entire working process of ions and electrons, the battery structure that affects the charge transfer, whether electrochemical or physical, will affect the function of fast charging.

Fast charging requires all parts of the battery

Regarding the battery, assuming the travel power function, the overall effort in every link of the battery is required, first including the positive electrode, negative electrode, electrolyte, gap and structural planning.

Anode

In fact, a variety of anode materials can be used to make almost all fast-charging batteries, first of all, to ensure the demand functions including conductivity (reducing internal resistance), March (ensuring reaction kinetics), body (not to clarify), safety (not to clarify, appropriate processing functions (product appearance is not too large, reduce vice, safety service). Of course, with respect to each specific data set, the problems to be solved may be different, but the public positive data set can be optimized to meet these requirements, but there are differences between different data sets:

A. Lithium iron phosphate may focus more on conductivity and low temperature problems. Carbon coating, moderate nano-sizing (note, moderate, of course not the thinner the better simple logic), and processing the formation of ion conductors outside the particles are the most typical strategies.

B, ternary data itself conductivity is now better, but the reaction activity is too high, so ternary nano rare operations (nanomedicine is not a panacea type information function, especially in the field of batteries and sometimes many reactions), more and more attention to safety and bay (electrolyte) vice, is actually a curse of ternary data is now safe, recently in Frequent safety accidents of batteries have put forward higher requirements.

C. Lithium manganese oxide is more about the life figures, and there are also many lithium manganese oxide fast charging batteries on the market.

Cathode

When lithium-ion batteries are charged, lithium moves to the negative electrode. And the high current of fast charging may cause the negative electrode potential to be more negative, the negative pressure sensitive to receive lithium becomes larger, and the tendency to generate lithium dendrites becomes larger, so fast charging, when the cathode is not only to meet the needs of lithium dysfunction dynamics, but also to deal with the formation of lithium dendrites, which often aggravates the safety problems brought about, therefore, the core difficulty of fast charging and the important technology of lithium ion embedding cathode.

, the negative data of the control position in the market is still graphite (accounting for about 90% of the market share), without his basic reasons, cheap (you feel that the battery is expensive every day, exclamation mark!), and graphite induction processing function, energy density is relatively good, relatively few defects. Of course, the graphite cathode also has problems. Its appearance is sensitive to the electrolyte, and the embedding response of lithium has a strong directionality, so after the surface treatment of graphite, its structure develops stably, which promotes the loosening of lithium ions, and on this basis, the important demand for directionality.

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