The industrial chain of lithium batteries is relatively mature and occupies a relatively high proportion in the field of electrochemical energy storage. Lithium battery companies in the world are seeking innovative methods, and the innovation trends of lithium-ion batteries is mainly to seek technological breakthroughs that are safer, more efficient, and lower cost based on existing technologies and industrial chains.
In terms of resource utilization, the development direction is mainly focused on lithium resource mining and recovery technology. In order to improve the enrichment of lithium ions, this requires a more simplified process and the development of separation materials towards higher performance adsorption. Ion exchange adsorption and membrane separation methods have advantages. Adsorption method: suitable for salt lakes with low lithium concentration, mainly relying on adsorbents with specific adsorption capacity for lithium ions to achieve the separation of lithium ions.
Aluminum-based adsorbents are relatively mature at present, but consume a lot of water. The direction of future technical transformation is mainly to reduce water consumption. Membrane separation method: It is one of the most active processes for industrial application at present. Through the pressure, the selective separation function of the membrane is used to separate the different components of the feed liquid. The core is the selection of membrane materials. The membrane materials for lithium extraction from salt lakes are mainly organic membranes, and China's organic membranes are in the stage of gradually realizing import substitution.
2. Lithium-ion battery cathode material
In terms of cathode materials, gradually increasing the energy density is the development trend of the lithium iron phosphate cathode, which can be promoted by means of lithium supplementation. Lithium supplementation, also known as pre-lithiation, introduces a substance with high lithium content into the battery material system, and makes the substance effectively release lithium ions, compensate for the loss of active lithium, and improve the actual energy density and cycle life of the battery.
The cathode lithium supplementation process is relatively mature. After the implementation of lithium supplementation technology, the energy density of lithium iron phosphate batteries is expected to increase by about 20%60. At present, some companies have carried out large-scale production, and it is expected that the production capacity will be released in the next 3-5 years.
3. Lithium-ion battery anode material
In terms of anode materials, the future development trend of lithium ion battery anode material companies mainly focuses on carbon-silicon composite materials with high specific capacity. Pure silicon materials are prone to volume expansion during charging and discharging, but carbon materials have the advantages of small volume changes. Therefore, the current development direction for industrialization is to introduce carbon materials into silicon to form silicon carbon anodes.
This process can increase the specific capacity of the anode, and at the same time alleviate the volume change of silicon during charge and discharge. At present, the amount of silicon doped in commercial silicon-carbon anodes is mostly below 10%, and the specific capacity is between 400-700mAh/g. The supporting industrial chain of carbon and silicon anodes has gradually matured and is expected to release production capacity in the next 2-3 years.
4. Lithium battery separator
In terms of lithium battery separator, the innovation trend mainly focuses on the preparation process and technology development. Lithium iron phosphate has a tendency to develop from dry separator to wet separator. For increased safety, ceramic coatings on wet-process separators are a further technological innovation.
5. Lithium battery electrolyte
In terms of electrolytes, improving the safety and stability of batteries is the future direction of lithium-ion batteries. In terms of liquid electrolyte, LiFSI has a good application prospect. LiFSI can be used as an electrolyte lithium salt in two ways. It can be used as a general lithium salt additive to form LiPF6-LiFSI mixed lithium salt, and pure LiFSI lithium salt can replace LiPF6. At present, LiFSI has been localized in China and is currently in the stage of small batch production. In the future, it will mainly reduce costs through mass production. Solid-state batteries refer to lithium-ion batteries using solid-state electrolytes.
In terms of working principle, solid-state lithium batteries are no different from traditional lithium batteries. For energy storage systems, the most significant advantage of solid-state lithium batteries is safety. Solid-state electrolytes have the advantages of flame retardancy and easy packaging, and can also increase the energy density of batteries. In addition, the solid electrolyte has high mechanical strength, which can effectively inhibit the penetration of lithium dendrites in liquid lithium metal batteries during cycling, making it possible to develop lithium metal batteries with high energy density.
Therefore, all solid state lithium batteries are an ideal development direction for lithium-ion batteries. However, it should be noted that in order to achieve a technological breakthrough in solid-state batteries, there are still two major challenges in materials science. One is the defect of the lithium metal anode, and the other is the failure of the solid-state electrolyte and the positive-negative interface. Since the solid electrolyte itself is heavier than the electrolyte and the separator, the cathode system has not changed. Therefore, to achieve the surpassing of the mass energy density, only by using the lithium metal anode, which can store lithium density about 10 times that of graphite.
For all solid state lithium batteries with lithium metal as the anode, the growth of lithium dendrites in the battery needs to be considered. Dendrite growth in solid electrolytes is more complex and diverse than in liquid electrolytes, mixing different physical and chemical environments, and the specific mechanism is still uncertain. The second is the failure of the interface between the solid electrolyte and the positive and negative electrodes. The poor contact between the inorganic electrolyte and lithium metal in the solid electrolyte will lead to high interfacial resistance and uneven current distribution, while the ability of the polymer electrolyte to maintain stable physical and chemical properties at the interface at room temperature is insufficient.
The two affect the long cycle life of all-solid-state lithium batteries by affecting the stability of the electrolyte interface. The research and development of solid-state batteries has gone through 40 years of history. In addition to the above-mentioned technical problems that have not been overcome, the compatibility of the industrial chain with the existing lithium-ion batteries is very small. Therefore, although solid-state lithium metal batteries are the ideal form of lithium batteries, if large-scale production is to be realized, more time needs to be invested in breaking through technical bottlenecks and supporting the construction of the industrial chain.