Nickel metal hydride battery electrode structure and active substances

Source: 2020 - 04 - 12 then hits: nickel metal hydride battery electrode structure and total active material 1. Sintered electrodes will be fiber nickel coating on the perforated nickel strip, and then high temperature sintering in the nitrogen/hydrogen environment. After coating binder used in the process of evaporation, leaving the conductive nickel skeleton, the average pore diameter of 30 m. Through chemical immersion method will nickel oxide deposition in the porosity of the sintered skeleton. Electrode through the charging and discharging process formation or activation. Sintered electrode is suitable for high power discharge, but its quality is given and specific storage volume to drop, the production cost is high, the production process is complex, now rarely used. 2. Paste electrode these electrodes are now more common than sintered electrodes, is by mechanical methods will be the average particle size of 10 m high density spherical nickel hydroxide confused on nickel foam substrate made of holes. Paste contains oxidation drilling additives such as conductive agent, the former can form a conductive network, to make up for a nickel hydroxide metal fluid and setting of the larger distance between nickel hydroxide, and nickel hydroxide itself with low conductivity. In recent years, research has increased paste electrode electrode than power and high energy discharge rate, make it reach the level of the sintered electrodes. 3. Non-woven nickel electrode with the method of chemical nickel plating, the first conductive coating plating on the special design of the three-dimensional structure of non-woven fabric, and then the plating. Nickel plating quantity limit within the 200 g/m2, less than half of the typical amount of nickel foam nickel electrode. 1 of active material of nickel metal hydride batteries. Active substances are positive active material of Ni ( 哦) 2 and NiOOH, but as a result of NiOOH is not stable, so the active material is usually Ni ( 哦) 2, it has a minus ni ( 哦) 2 and n - ni ( 哦) 2 two forms. π- ( 哦) The electrochemical activity of 2 higher than pico - ni ( 哦) 2. NiOOH 'ooh' and 'ooh' two kinds of crystal. According to the form of active material, can be divided into ordinary and ball type two kinds. Ordinary nickel ( 0 h) : from the traditional precipitation method, the nucleation rate is far higher than that of crystal growth rate during the preparation, so the vibration of low density, reduced electrode packing density, specific surface area is large, electrode mechanical stability is reduced, the life be affected. The spherical powder mainly control the Ni ( 哦) 2 way of crystal growth and morphology and particle size, thereby greatly improving the electrode packing density, improve the specific capacity of electrode. The spherical Ni ( 哦) 2 is the mh - Ni battery positive electrode of the active material, its loose load density for & gt; 1. 5 g/ml, vibration of solid density for & gt; 2. 0g/ml。 Its theoretical discharge capacity is 289 mAh/go2. The preparation of active substances chemical precipitation in the production of active substances Ni ( 哦) There are many different kinds of 2. Adding NiS04 solution and NaOH solution gradually to the ammonia containing ( PH = 12。 2 - 12. 4) The alkali resistance of reactor, constantly stirring under the conditions of reaction, generate Ni ( 哦) 2 precipitation. Control the reaction temperature 60 70 'c, washed to 90 - after precipitation 100 ℃ oven drying, screening of Ni ( 哦) 2 product. Vibration density of about 1. 77 g/cm3, volume of 0. 252 ah/g0 advantage is process principle of the method is simple, low energy consumption, low requirement for raw materials and equipment, product size and packing density is controlled. But many process parameters influencing performance index ( Reaction time, reaction temperature, solution pH, stirring conditions, feed speed, drying temperature, kinds of additives, etc. ) Performance difference, resulting in different batches, which affects the battery the stability of product performance.