CN101985351A

CN101985351A - Method for preparing simple and cheap lithium-ion power battery anode materials

Info

Publication number: CN101985351A
Application number: CN 201010503105
Authority: CN
Inventors: 徐庆宇; 沈凯
Original assignee: Southeast University
Current assignee: Southeast University
Priority date: 2010-09-30
Filing date: 2010-09-30
Publication date: 2011-03-16

Abstract

The invention discloses a method for preparing simple and cheap lithium-ion power battery anode materials. The method comprises the steps of: dissolving proper matched raw materials Fe(NO3)3.9H2O, NH4H2PO4, CH3COOLi.2H2O and C4H6O6 (tartaric acid) in de-ionized water, directly putting the solution in a furnace filled with argon for sintering without oxygen, drying at 60 to 95 DEG C, sintering at 120 to 170 DEG C for further dehydration, sintering at 300 to 350 DEG C for fully resolving raw materials, and then sintering for more than 10 hours in the furnace at 650 to 800 DEG C, and finally naturally reducing the temperature to room temperature so as to acquire the target product. In order to better crystallize, the materials can be grinded at room temperature and then be sintered at the same sintering temperature for 10 hours in the argon protection atmosphere. The invention has the advantages of simple device and technique, cheap raw material, easy operation, environmental protection and general applicability.

Description

The preparation method of the lithium ion power battery cathode material of cheap and simple

Technical field

The present invention relates to a kind of LiFePO of cheap and simple ₄The preparation method, belong to the synthetic field of inorganic nano material.

Background technology

Lithium-ion-power cell is the novel high-energy battery of succeeding in developing in 20th century.Since the last century the nineties, lithium ion battery has obtained develop rapidly.Because its high working voltage, heavy body, high-energy-density and excellent cycle performance, Application Areas more and more widely.LiFePO ₄Be the nearest 2 years just fast-developing positive electrode materials that get up, its higher safety performance, good high-temperature stability, superior cycle performance, impulse electricity flattens slow, low price, nontoxic, Environmental compatibility is good, rich in mineral resources, higher specific storage (theoretical capacity 170mAh/g, energy density 550Wh/kg) and higher operating voltage (3.4V, with the metallic lithium is negative pole) make it have broad application prospects as power cell and standby power supply field, be expected to become the main force of anode material for lithium-ion batteries of future generation.

LiFePO ₄Because Fe ²⁺Ionic exists, thereby its preparation technology requires sintering in the environment of starvation.General preparation technology comprises high-temperature solid phase reaction method, hydrothermal method, microwave process for synthesizing and sol-gel method etc.The difficult point of solid reaction process is that raw material is difficult for mixing, and sintering process produces a large amount of gas.The shortcoming of hydrothermal method need to be high temperature high voltage resistant equipment, and the difficulty of suitability for industrialized production is big, and the shortcoming of microwave process for synthesizing is that the equipment input is bigger, is difficult to industrialization.Sol-gel method is by forming uniform sol with metal-salt through hydrolysis, obtain required inorganic powder material by dry and roasting, this method has chemical uniformity good (can reach the molecular level level), the purity height, particle is thin, advantages such as thermal treatment temp is low are because we adopt this method to prepare LiFePO ₄Common Fe ²⁺The ionic cost of material is higher, and therefore a large amount of work concentrates on and utilizes cheap Fe ³⁺The ionic raw material, by in the preparation process with Fe ³⁺Ion is reduced into Fe ²⁺Ion is with preparation LiFePO ₄Usually adopt oxalic acid, organic raw material such as sucrose provide reduction reaction required carbon.For sol-gel method, the selection of complexing agent is most important, and suitable complexing agent will help LiFePO ₄The one-tenth phase.We use for reference multi-ferroic material BiFeO ₃Adopt tartrate to make complexing agent among the preparation technology, can well suppress the formation of dephasign, under lower sintering temperature, obtain very pure single-phase BiFeO ₃(S.Ghosh, et al.J.Am.Ceram.Soc.88,1349 (2005))).Utilize Prepared by Sol Gel Method LiFePO at us ₄Process in, an amount of tartrate both provided Fe ³⁺Reduce needed carbon, also help LiFePO simultaneously as complexing agent ₄The one-tenth phase.Can be after in proportion proportioning raw materials being become solution a step sintering directly obtain the LiFePO of pure phase ₄

Summary of the invention

Technical problem: technical problem to be solved by this invention provides a kind of simple, pervasive and economic lithium ion power battery cathode material LiFePO ₄The preparation method.

Technical scheme: the LiFePO of cheap and simple of the present invention ₄The preparation method may further comprise the steps:

1), 1: 1: 1 in molar ratio: 1 ratio was with raw material Fe (NO ₃) ₃9H ₂O, NH ₄H ₂PO ₄, CH ₃COOLi2H ₂O, C ₄H ₆O ₆Be dissolved in and form solution in the deionized water;

2), solution is put into the stove of logical argon gas atmosphere protection, 60 ℃～95 ℃ following sintering dehydrations are 3 hours～5 hours;

3), furnace is risen to 120 ℃～170 ℃, with abundant dehydration 25～35 minutes;

4), furnace is risen to 300 ℃～350 ℃, raw material was fully decomposed 3 hours～5 hours;

5), furnace is risen to 650 ℃～800 ℃, sintering 9 hours～10 hours, cooling naturally obtains basic product LiFePO then ₄

Described basic product is put into the stove of argon gas atmosphere protection again after grinding under air at room temperature, furnace is risen to 650 ℃～800 ℃, reburns and ties 9 hours～10 hours, and cooling naturally obtains the more crystalline degree then, promptly obtains final product LiFePO ₄

The described C of step 1) ₄H ₆O ₆Selection both be Fe ³⁺Be reduced to Fe ²⁺Reductive agent is provided, and is again that complexing agent helps LiFePO simultaneously ₄The one-tenth phase, under 650 ℃ to 800 ℃ preparation temperature, form the LiFePO of pure phase ₄

Beneficial effect:

(1) the Prepared by Sol Gel Method technology of Cai Yonging is simple, easy handling.

(2) used raw material, particularly iron nitrate is cheap;

(3) tartaric interpolation provides an amount of carbon for reduction reaction again both as complexing agent.

(4) because tartaric good complex performance makes sintering temperature that very big scope be arranged, even still can obtain the LiFePO of pure phase to 800 ℃ sintering temperature ₄

Description of drawings

Fig. 1 pressed 1: 1: 1 for raw material: 650 ℃ of 1 proportionings prepared (a), (b) 700 ℃, (c) 750 ℃, (d) 800 ℃ of following agglomerating LiFePO ₄The XRD figure of nanometer powder (e) is ground again at 650 ℃ of following agglomerating LiFePO behind 650 ℃ of sintering again ₄The XRD figure of nanometer powder.

Embodiment

1), at first selects proper raw material proportioning.According to LiFePO ₄Molecular formula, Fe (NO ₃) ₃9 _H2O, NH ₄H ₂PO ₄, CH ₃COOLi2H ₂1: 1: 1 in molar ratio mixed of this three kinds of raw materials of O.Tartaric selection is most crucial, on the low sidely will cause Fe ³⁺Reduction insufficient, excessively then cause too much carbon, thereby influence LiFePO ₄The efficient of product.In the groping of cut-and-try work, we find that optimum proportion is and the three kinds of the same mole numbers of raw material in front, and promptly four kinds of raw materials all are 1: 1: 1: 1 mixed;

2), in the raw material of above-mentioned suitable proportion, add deionized water, by stirring at room formation solution (the heating back is because tartaric existence forms gel);

3), under the room temperature complete lysigenous solution directly be placed in the tube furnace, logical argon gas atmosphere protection is with starvation atmosphere.Earlier 60 ℃～95 ℃ bakings with the moisture in the volatilization colloidal sol, again 120 ℃～170 ℃ bakings thoroughly to slough moisture.Temperature rises to 300 ℃～350 ℃ fully decomposes raw material.(650 ℃ can obtain monophasic LiFePO to 800 ℃ to rise to 650 ℃ of required agglomerating temperature at last ₄), sintering 10 hours.At last be cooled to room temperature naturally and promptly obtain monophasic LiFePO ₄Nanometer powder.

4), in order to improve LiFePO ₄Crystal property, the LiFePO that step 3 is obtained ₄Nanometer powder can at room temperature fully grind in the stove that is placed into logical argon gas atmosphere protection again, and 650 ℃ of sintering temperatures 10 hours, natural cooling can get the good LiFePO of crystal property ₄

Further specify the present invention below in conjunction with drawings and Examples, wherein the part preparation condition only is the explanation as typical case, is not limitation of the invention.

1), according to groping us and finds raw material Fe (NO in the experiment ₃) ₃9H ₂O, NH ₄H ₂PO ₄, CH ₃COOLi2H ₂O and tartaric optimum proportion are 1: 1: 1: 1, and Zhi Bei sample F e like this ³⁺Ion is reduced into Fe fully ²⁺Ion, and residual carbon is considerably less, carbon content is about 6% (with the atomic percent of Fe).

2), with raw material Fe (NO ₃) ₃9H ₂O, NH ₄H ₂PO ₄, CH ₃COOLi2H ₂O and tartrate are 1: 1: 1 in proportion: 1 mix to add deionized water wiring solution-forming (can be dissolved at raw material under the prerequisite of water and reduce the water yield to shorten time of drying as far as possible), put into tube furnace, feed argon gas with starvation, keep 30 minutes with oven dry moisture at 90 ℃ earlier.

3), be warming up to 150 ℃ of maintenances 30 minutes, so that the thorough dewatered and washed branch of raw material.

4), be warming up to 300 ℃ of maintenances 3 hours, so that raw material thoroughly decomposes.

5), be warming up to 650 ℃ and kept 10 hours, raw material is fully reacted obtains LiFePO ₄Nanometer powder, cooling obtains final product naturally, and sample is the particle of diameter hundreds of nanometer.We have attempted sintering temperature and have been up to 800 ℃, can both obtain the product (Fig. 1) of pure phase.

6), in order to obtain the more crystalline degree, can with product at room temperature air atmosphere grind down, put into the tube furnace of argon gas atmosphere protection again, 650 ℃ of following sintering 10 hours, lowering the temperature naturally obtained the better product of crystallization (Fig. 1).And by sintering again after grinding, the particulate dimensional homogeneity obtains very big improvement.

The invention provides a kind of LiFePO of cheap and simple ₄Preparation method's thinking and implementation method, concrete application approach is a lot, the above only is a preferred implementation of the present invention, should be understood that, for those skilled in the art, under the prerequisite that does not break away from the principle of the invention, can also make some improvement, for example the coating of carbon is raising LiFePO commonly used at present ₄The method of efficient, can control by the consumption that increases suitable adjustment tartrate raw material in the method, these improvement also should be considered as protection scope of the present invention.

Claims

1. the preparation method of the lithium ion power battery cathode material of a cheap and simple is characterized in that this method may further comprise the steps:

2. the preparation method of the lithium ion power battery cathode material of cheap and simple according to claim 1; it is characterized in that described basic product; put into the stove of argon gas atmosphere protection after under air at room temperature, grinding again; furnace is risen to 650 ℃～800 ℃; reburn and tied 9 hours～10 hours; naturally lower the temperature then, obtain the LiFePO of better degree of crystallinity ₄