Method for preparing manganese phosphate lithium / carbon composite material

Abstract

The invention discloses a solid-liquid combined method for preparing a manganese phosphate lithium / carbon composite material. According to the method, raw materials comprising ammonium dihydrogen phosphate, a lithium source, a manganese source, an iron source, a carbon source and metal doped elements are mixed, dried, heated to 450-700 DEG C under atmosphere conditions, dried for 1-12 h at the constant temperature, and cooled to obtain the manganese phosphate lithium / carbon composite material. The invention adopts a principle of solid-liquid combination, effectively improves uniformity of material mixing, and facilitates improvement on stability and degree of crystallinity of the product. The composite material synthesized by the method is uniformly dispersed, and has effectively improved electronic conductivity. One-time calcination adopted by the invention can effectively reduce energy consumption; and the obtained composite material has particle size distribution of 1-20 mum, and 0.1C rate discharge capacity of 142mAh / g; and electrochemical tests show that the electrode has obvious discharge platform at about 4V, high discharge capacity and good cycle stability.

Description

technical field [0001] The invention belongs to the field of materials science, and in particular relates to a preparation method of lithium iron manganese phosphate / carbon composite material. Background of the invention [0002] The development of lithium-ion secondary batteries has a history of 20 years. So far, the transition metal oxides that can form intercalated compounds with lithium are the most researched. In the past two decades, people have found six practical positive electrode active materials through the research on lithium-ion secondary battery electrode materials: lithium cobaltate (LiCoO 2 ), lithium nickelate (LiNiO 2 ), lithium manganate (LiMn 2 o 4 ), lithium vanadate (Li 1+x V 3 o 8 ), lithium vanadium phosphate (Li 3 V 2 (PO 4 ) 3 ) and lithium iron phosphate (LiFePO 4 ) and various doping compounds derived from them. LiCoO 2 It is highly toxic and expensive, and it is difficult to guarantee the safety when making large-scale power batterie...

AI Technical Summary

Problems solved by technology

However, since LiMnPO 4 The material is extremely poorly conductive and is considered an insulator, leading to the synthesis of LiMnPO capable of reversible charge and discharge 4 Very difficult, which limits its development and application

[0004] In many patent application numbers of lithium manganese iron phosphate / carbon composite materials, the electrochemical performance of the material is improved through carbon coating and metal doping, and a relatively ideal capacity is obtained, but the preparation methods are relatively cumbersome, and most of them are two Secondary mixing or secondary calcination greatly lengthens the process flow, increases the difficulty of its industrialization, increases the cost and makes it difficult to guarantee the batch nature of the product, making it more difficult to improve and solve the problem in the battery factory.

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