Advance in Battery Technology Series No. 19: The positive pole of ferromanganese-liperidite structure is further advanced


The main bottleneck of insufficient energy density of lithium battery lies in the low specific capacity of the positive electrode (relative to the negative electrode) and low voltage to lithium.Currently, the widely used cathode materials include layered materials, spinel and olivine according to different crystal structures.Lithium iron phosphate with olivine structure has higher intrinsic safety and cost advantages, but compared with ternary lithium, it has lower voltage, smaller theoretical capacity and insufficient intrinsic conductivity.For higher average voltage, the theoretical specific capacity of olivine structure cathode materials is about 170mAh/g, but the lithium voltage varies.The voltage of lithium iron phosphate to lithium is the lowest, only about 3.5V;Lithium manganese phosphate is as high as 4.1V, but is not widely used due to its very low conductivity, low stability, and manganese leaching.It is possible to obtain a higher average voltage than lithium iron and maintain other properties by mixing iron and manganese atomic grade to obtain lithium iron manganese phosphate.There are many key parameters of lithium iron manganese phosphate cathode material.If a positive electrode with suitable fe-Mn ratio, uniform distribution of main components, uniform particle size, regular surface morphology, reasonable distribution of doping elements, successful construction of conductive coating and relatively low cost can be obtained, the energy density advantage of the corresponding battery can be fully played.Patent layout: the key point is that there are about 700 patents in the effective, substantial review and public state of the cathode of the synthetic lithium iron manganese phosphate battery, and the main applications are in China.The experimental results of the main patent show that the sample performance data of the liquid phase mixed reaction of iron and manganese elements is relatively good: the discharge capacity under the condition of low rate is generally 150mAh/g level;There are also some embodiments with high discharge capacity.At the same time, some patents describe the means of modifying iron manganese lithium, such as magnesium doping, titanium nitride coating, etc.Away from expensive elements, toward a challenging future lithium iron phosphate has returned to the mainstream of power battery installation, and energy storage applications have broad prospects.If the research and development and industrialization of lithium ferromanganese phosphate positive electrode progress smoothly, we estimate that the energy density of lithium ferromanganese phosphate cell is about 216Wh/kg when the energy density of lithium ferromanganese phosphate cell is 187Wh/kg, leading by about 15.6%;Ferro-manganese-lithium and ternary positive doped/composed “AB batteries” may also be quite promising.At the same time, we estimate that the cost of the positive electrode is comparable to that of the lithium iron phosphate after the technology is mature, and it is expected to become an important dynamic positive electrode and even a potential positive energy storage material.Investment evaluation and Recommendations Investors are advised to focus on companies that have patented the synthesis of ferromanganese-lithium phosphate.Engineering ability is the key to the effective application of iron, manganese and lithium, and large-scale experience and technical level of materials will directly determine the progress of its industrialization.In addition, it is also recommended to pay attention to the material system optimization prospective system research and development companies in olivine structure cathode.Risk analysis The comprehensive performance of the positive electrode or corresponding battery is not as expected, the scale progress is not as expected, and the cost competitiveness is not as expected.

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