Neutron diffraction data clearly reveals the process of Li + embedded in anode graphite structure, under the C / 20 charge ratio, first of all, Li + generated LiC12 reaction with graphite, when the battery capacity of 1009 mah about 50% (SoC), the diffraction peak of LiC6 began, when the battery 1687 mah, LiC6 diffraction peak strength greatly increased, more than LiC12 diffraction peak intensity. Under the 1 c rate charging, by contrast, after the diffraction peak intensity of LiC6 than LiC12 diffraction peaks, indicating that Li + is not 100% conversion in the graphite structure, only part of the lithium is embedded into the graphite crystal structure, the other part of lithium precipitation in the form of metallic lithium, but on the diffraction curve has not see metallic lithium electricity diffraction peak, it shows that the analysis of the lithium quantity is less, the means of neutron diffraction tests.
At the end of the charging, the cylindrical power lithium-ion batterie needs to stand for 4 h, to leave after the battery in the detection of the neutron diffraction, specific results as shown in the figure below, you can see from the curve, after 4 h of incubation, the diffraction peak intensity of LiC6 enhanced obviously, and LiC12 the intensity of diffraction peaks decreases significantly, especially in 1 c rate charging battery this change is more significant, this is mainly benefited from the cathode internal lithium concentration between the parts of "rebalancing". However, compared with the C / 20 multiplier battery, the peak value of LiC6 of the 1C multiplier battery is significantly lower, which indicates that some lithium precipitated from the negative electrode surface is irreversible.
In addition to the neutron diffraction, Christian von Lu ̈ ders also tested the battery stand for battery voltage curve in the process, as shown in the figure below, can see from the graph, charge ratio and C / 2 or more batteries, have appeared in the process of voltage static platform, a voltage for C / 2 rechargeable batteries, the length of time the voltage platform for 2 h, 1 C for charging the battery, the voltage platform length is 3 h. According to the neutron diffraction data, the voltage platform mainly corresponds to the process of precipitation lithium reembedding into the graphite crystal structure.
Under different ratio of the amount of lead to the analysis of lithium in the following figure, can see from the chart, the analysis of the High security rechargeable lithium battery with the increase of charging ratio of lithium quantity increase gradually, especially after ratio greater than C / 2, there is an obvious increase amount of formation of lithium battery, but it's important to note that even under the small ratio of C / 20 still appeared around 3% of the amount of lithium.