Researchers invent new coatings and solid composite electrodes to improve rechargeable battery 18650 3.7v capacity and safety

　　According to foreign media reports, researchers from Stanford University and SLAC National Accelerator Laboratory published a study in the journal Joule stating that they invented a new coating that can make lightweight metal lithium batteries safe and durable. This will lead to the next generation of electric vehicles.

　　In laboratory tests, the coating significantly extended the life of the battery, and it also dealt with combustion issues by greatly limiting the lithium evolution that penetrated the separator between the positive and negative electrodes of the battery.

　　The researchers note that lithium metal batteries have at least one-third more energy per pound than lithium-ion batteries and are very lightweight because they use lightweight lithium as the positively charged end rather than heavier graphite. Portable electronics, from laptops to cell phones, would benefit if lithium metal batteries were more reliable, but the real source of revenue would be cars. The biggest obstacle to electric vehicles is that batteries account for a quarter of the cost, which goes to the core of the production cost of electric vehicles.

　　The capacity of traditional lithium-ion batteries has been developed to its limit, so it is crucial to develop new batteries to meet the high energy density requirements of modern electronic devices.

　　The Stanford and SLAC research teams tested their coating on the positively charged end of a standard metallic rechargeable battery 18650 3.7v, called the anode, where lithium deposits typically form. Ultimately, they combined the specially coated anode with other commercially available components to create a fully operational battery. After 160 cycles, their lithium metal battery can still provide 85% of the energy it produced during the first cycle. Ordinary metal lithium batteries will only release about 30% of their energy after so many cycles. Even if they don't explode, they won't be of much use.

　　The new coating blocks the formation of lithium by forming a molecular network that evenly transports charged lithium ions to the electrode. It prevents unnecessary chemical reactions in these batteries and also reduces the buildup of chemicals on the anode before they destroy the battery's ability to deliver power.

　　The research team is currently improving its coating design to test the cells over more cycles and improve capacity retention.

　　solid composite electrode

　　The top academic journal "Matter" published the latest results of Professor Ma Cheng of the University of Science and Technology of China and his collaborators in August. This result proposes a new strategy that can effectively solve the key problem of poor contact between electrode materials and solid electrolytes in next-generation solid-state lithium batteries. The synthesized solid-state composite electrode exhibits excellent capacity and rate performance.

　　Current mainstream lithium batteries use liquid electrolytes, which pose safety risks such as fires, and the energy that can be stored in a specific volume is limited. However, the next generation of solid-state lithium batteries that can solve these problems still has many unsolved problems. Replacing the organic liquid electrolyte in traditional lithium-ion batteries with solid electrolytes can greatly alleviate safety issues and is expected to break through the "glass ceiling" of energy density. However, mainstream electrode materials are also solid substances. Since the contact between two solid substances is almost impossible to be as full as solid-liquid contact, it is difficult for batteries using solid electrolytes to achieve good electrode-electrolyte contact, and the overall performance of the battery is also not good. Satisfactory.

　　Ma Cheng's team and their collaborators conducted atomic-level observations of the impurity phase in a solid-state electrolyte with a classic perovskite structure. Although the structures of the impurities and the solid-state electrolyte were very different, the researchers observed that their atoms interacted with each other at the interface. Extensional formal arrangement. After a series of detailed structural and chemical analyses, the researchers found that this impurity phase has the same structure as the high-capacity lithium-rich layered electrode.

　　Using the observation results, the researchers crystallized amorphous powder with the same composition as the perovskite solid electrolyte on the surface of the lithium-rich layered particles, and successfully achieved sufficient and tight contact between the two solid-state materials in the new composite electrode. touch. The electrode-electrolyte contact problem is solved, and the rate performance of this solid-solid composite electrode is comparable to that of the solid-liquid composite electrode. More importantly, the researchers also found that this epitaxial solid-solid contact can tolerate large lattice mismatches, so their proposed strategy can be applied to a variety of perovskite solid-state electrolytes and layered electrodes.

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