What are the possible advantages of all-solid lithium secondary batteries?

The all-solid lithium secondary battery has attracted the attention of the international giants because it is expected to solve the two "challenges" currently plaguing the power battery industry: safety hazards and low energy density. The advantages of all-solid lithium batteries over liquid lithium ion batteries include:

(1) High safety performance

Since the liquid electrolyte contains flammable organic solvents, sudden temperature rise in the event of an internal short circuit can easily cause combustion or even explosion. It is necessary to install a structure of safety devices that resist temperature rise and prevent short circuits. This will increase costs but still can not completely solve the safety problem.. Tesla, known as BMS, is the best in the world. In this year alone, two ModelS had a serious fire.

Many inorganic solid electrolyte materials are non-flammable, non-corrosive, non-volatile, and do not have leakage problems. They are also expected to overcome the phenomenon of lithium dendrites. Therefore, all-solid lithium secondary batteries based on inorganic solid electrolytes are expected to have high safety characteristics.

Polymer solid electrolytes still have certain combustion risks, but compared with liquid electrolyte batteries containing flammable solvents, the safety is also greatly improved.

(2) High energy density

At present, the core energy density of lithium-ion batteries used in the market is up to about 260Wh / kg, and the energy density of lithium-ion batteries under development can reach 300-320Wh / kg. For all-solid lithium batteries, if the negative electrode uses metallic lithium, the battery energy density is expected to reach 300-400Wh / kg, or even higher.

It should be noted that because the density of solid electrolytes is higher than that of liquid electrolytes, the energy density of lithium batteries of liquid electrolytes is significantly higher than that of all-solid lithium batteries for the same system of positive and negative materials. The reason why the all-solid lithium secondary battery has a high energy density is because the negative electrode is likely to use metallic lithium materials.

(3) Long cycle life

Solid electrolytes are expected to avoid the problem of continuous formation and growth of solid electrolyte interface membranes during charging and discharging of liquid electrolytes and the problem of lithium dendritic diaphragm, which may greatly improve the circulation and service life of metallic lithium batteries.

The thin-film all-solid lithium metal battery has been reported to be able to cycle 45,000 times, but at present, large-capacity lithium metal batteries have not been reported to have a long cycle life, mainly the current high-capacity lithium metal electrode(& GT; 3mAh/cm2) has poor cyclic performance.

(4) Wide operating temperature range

If all solid lithium batteries use inorganic solid electrolytes, the maximum operating temperature is expected to increase to 300 °C or even higher. At present, the low-temperature performance of large-capacity all-solid lithium batteries needs to be improved. The operating temperature range of specific batteries is mainly related to the high and low temperature characteristics of electrolytes and interface resistors.

(5) Electrochemical window width

The electrochemical stability window width of the all-solid lithium battery is likely to reach 5V, which is suitable for the Gaodianya electrode material and is conducive to further improving the energy density. At present, thin film lithium batteries based on lithium nitride phosphate can work at 4.8 V.

(6) Flexibility

All-solid lithium batteries can be prepared into thin film batteries and flexible batteries, and can be used in smart wearable and implantable medical equipment in the future. Compared with flexible liquid electrolyte lithium batteries, packaging is easier and safer.

(7) Convenience of recovery

Battery recycling is generally two methods, one is wet and the other is dry. The wet method is to remove the toxic and harmful liquid cores inside, and the dry method is to remove the effective ingredients such as fragmentation. The advantage of all-solid lithium batteries is that they do not have liquids in themselves, so theoretically there should be no waste liquid, which is relatively simple to handle.

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