What is the effect of poor batch consistency on the performance of lithium ion batteries?

For battery manufacturers, the smaller the difference between the batch of positive materials, the better the consistency, the more stable the performance of the finished battery. We all know that one of the most important disadvantages of lithium ferric phosphate positive electrode materials is the poor stability of batches. When making pulp, due to the large fluctuations in batches, the viscosity and solid content of each batch of slurry are unstable, which brings problems to users., The process needs to be constantly adjusted to adapt.

Increasing the degree of automation of production equipment is the main means to improve the stability of the batch of lithium iron phosphate materials. However, at present, the equipment automation of domestic suppliers of lithium iron phosphate materials is generally low, and the technical level and quality management ability are not high. There are varying degrees of batch instability in the materials provided. From the user's point of view, if the batch difference can not be eliminated, we hope that the larger the weight of a batch, the better, provided that the same batch of material is uniform and stable. Therefore, in order to achieve this requirement, the iron lithium material supplier often adds a step mixing process after making the finished product, that is, the uniform mixing of several batches of materials, and the larger the volume of the mixing kettle, the more materials it contains. The larger the amount of a batch is. The diameter, specific surface area, moisture, pH of ferric lithium materials will affect the viscosity of the resulting slurry, but often these indexes have been strictly controlled within a certain range, but there will still be large differences in the viscosity of the batch slurry. the situation, In order to prevent abnormal mass use, some slurry test viscosity is often prepared in advance before the analog production formula is put into use, and it is put into use after meeting the requirements. However, if the battery manufacturer conducts tests before each production, the production efficiency will be greatly reduced. Therefore, this work is put forward to the material supplier, and the material supplier is required to complete the test before shipping. Of course, with the Advancement of technology, the improvement of the material supplier's process ability, the distribution of physical specifications is getting smaller and smaller, the pre-delivery test viscosity step can be saved. In addition to the measures mentioned above to improve consistency, we should also use quality tools to minimize this batch instability and prevent quality problems. Mainly from the following aspects.

(1) Establishment of operating procedures.

The inherent quality of the product is designed and manufactured. Therefore, how operators operate is particularly important for controlling product quality, and detailed and specific operating standards should be established.

(2) Identification of CTQ.

Key indicators and processes that affect product quality should be identified, and these key control indicators should be specifically monitored and emergency response measures should be developed. The normal phosphoric acid railway line is the mainstream of the current preparation of lithium iron phosphate. Its processes include ingredients, ball milling, sintering, crushing, packaging, etc.. The ball milling process should be managed as a key process because the consistency of particle size after ball milling is not controlled properly., The particle size consistency of the finished product will be affected, which will affect the batch consistency of the material.

(3) Use of SPC.

The SPC monitors the key characteristics of the key processes from time to time, analyzes the anomalies, finds out the causes of instability, takes effective corrective measures and preventive measures, and avoids the flow of bad products to the client.

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