Prelithiation technology is widely considered a feasible route to raise the energy density and elongate the cycle life of lithium‐ion batteries. The principle of prelithiation is to introduce extra active Li ions in the battery so that the lithium loss during the first charge and long‐term cycling can be compensated. Such an effect does not need to change the major electrode material or battery structure and is compatible with the majority of current lithium‐ion battery production lines. At this stage, various prelithiation methods have been reported, some of which are already in the pilot‐scale production stage. But there is still no definitive development roadmap for prelithiation. In this review, we first introduce the influence of prelithiation on electrochemical performance from a theoretical point of view and then compare the pros and cons of different prelithiation methods in different battery manufacturing stages. Finally, we discuss the challenges and future development trends of prelithiation. We aim to build up a bridge between academic research and industrial application. Some engineering problems in the promotion of prelithiation technique are extensively discussed, including not only the implementation of prelithiation but also some collateral issues on battery designing and management.
The application of solid polymer electrolytes (SPEs) is severely impeded by the insufficient ionic conductivity and low Li+ transference numbers (tLi+). Here, we report an iodine‐driven strategy to address both the two long‐standing issues of SPEs simultaneously. Electronegative iodine‐containing groups introduced on polymer chains effectively attract Li+ ions, facilitate Li+ transport, and promote the dissociation of Li salts. Meanwhile, iodine is also favorable to alleviate the strong O−Li+ coordination through a Lewis acid–base interaction, further improving the ionic conductivity and tLi+. As a proof of concept, an iodinated single‐ion conducting polymer electrolyte (IPE) demonstrates a high ionic conductivity of 0.93 mS cm−1 and a high tLi+ of 0.86 at 25 °C, which is among the best results ever reported for SPEs. Moreover, symmetric Li/Li cells with IPE achieve a long‐term stability over 2600 h through the in‐situ formed LiF‐rich interphase. As a result, Li−S battery with IPE maintains a high capacity of 623.7 mAh g−1 over 300 cycles with an average Coulombic efficiency of 99%. When matched with intercalation cathode chemistries, Li/IPE/LiFePO4 and Li/IPE/LiNi0.8Mn0.1Co0.1O2 solid‐state batteries also deliver high‐capacity retentions of 95% and 97% at 0.2 C after 120 cycles, respectively.
The
uneven distribution of state of charge (SoC) in the
lithium-ion
battery is a key factor to cause fast decay of local electrochemical
performance. Here, we report an acoustic method to realize SoC mapping
in a pouch cell. A focused ultrasound beam is used to scan the cell,
and the transmitted ultrasonic wave is analyzed with a deep learning
algorithm based on the feedforward neural network. The deep learning
algorithm effectively suppresses the disturbance of structural variation
in different cells. As a result, the root mean squared error (RMSE)
of the estimated local SoC is reduced to 3.02% when applying to different
positions on different pouch cells, which is 11.07% of the RMSE by
direct fitting SoC with acoustic time of flight. Combining with the
progressive scanning technique, our method can realize non-destructive in situ SoC mapping with 1 mm in-plane resolution on pouch
cells.
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