Detailed reason for the failure of lithium battery

Auctor Iflowpower - Portable Power Station supplementum

1 Lithium ion battery failure classification In order to prevent the above-mentioned performance attenuation and battery safety issues, the failure decomposition of lithium-ion batteries is bound to. The failure of the lithium-ion battery refers to the failure and safety failure of the battery performance attenuated by certain essential properties or abnormal use of performance. 2 The original lithium ion battery failure can be divided into endome and external causes.

The internal principle is the physical and chemical variation of the invalidation, the research scale can be traced back to the thermodynamics of the atomic, molecular scale, and the research failure process. 外界因素包括撞击、针刺、腐蚀、高温燃烧、人为故障等。 3 Common failure performance of lithium ion batteries and its failure mechanism decomposition capacity attenuation failure: When the standard circulation life detection, the number of cycles reaches 500 times when the discharge capacity should not be less than 90% of the initial capacity.

或者循环次数达到1000次后，放电容量不应低于初始容量的80%。 如果在标准循环内容量出现急剧下降的情况，就属于容量衰减失效。 电池容量衰减失效的根源是材料失效，且与电池制造工艺、电池使用情况等客观因素密切相关。

From the perspective of material, the fact that the fails to fail, the structural failure of the positive electrode material, the transition growth of the negative surface SEI, the electrolytic liquid and the deterioration, the fluid corrosion, the system trace impurities, etc. The structural failure of the positive electrode material: the structural failure of the positive electrode material includes cathode material particles, irreversible transformation, material dissemination, etc. LIMN2O4 will cause distortion to the Jahn-Teller effect during the charge and discharge process, and even particle rupture, resulting in electrical contact between particles.

LiMn1.5Ni0.5O4 material The four-square crystal system in the charge and discharge process, LiCoO2 material caused CO into the Li layer due to the transition of Li, caused the layered structure, restricting the layered structure during charge and discharge.

容量。 The negative electrode material failure: the failure of the graphite electrode occurs in the surface of the graphite, the graphite surface is reacted with the electrolytic solution, and the solid electrolyte interface phase (SEI) is machined. If excessive growth can cause the lithium ion content in the internal system, the result is caused by capacity attenuation.

The failure of silicon negative electrode materials is the cycle performance problem caused by its huge volume expansion. Electrolyte failure: LIPF6 stability is poor, easy to analyze to reduce the migration of Li + content in electrolyte. It is also easy to form HF with trace reactions in the electrolyte, resulting in corrosion inside the battery.

气密性不好会造成电解液变质，电解液的粘度和色度变差，最终导致传输离子性能的急剧下降。 收集器故障：收集液腐蚀，收集器浓度下降。 被上述电解液褪色的HF，会造成集电体的腐蚀，产生不良的导电性，结果造成欧姆接触增加或活性物质失效。

在充放电过程中，Cu箔在低电位下溶解，沉积在正极表面，这就是所谓的铜。 常见的集体失效形式不足以导致团块与活性物质之间发生剥离，不能为电池提供容量。 Internal resistance increase: The lithium ion battery internal resistance conference accompanied by energy density, voltage and power decrease, battery heat and other failure problems.

Metal factors leading to increased lithium-ion battery internal resistance are divided into battery-key materials and batteries. Battery Key Material: The microcrack and rupture of the positive electrode material, the damage of the negative electrode material is too thick, the electrolytic solution aging, the active material is detached from the current, and the contact of the active material and the conductive additive is worse (including the loss of conductive additives). Diaphragm, blockage, battery extreme ear welding abnormalities, etc.

电池使用环境：环境温度过高/过低、过充、高倍率充放电、制造工艺及电池设计结构等。 Internal short circuit: internal short circuit tends to cause self-discharge, capacity attenuation, local thermal out of control, and cause safety accidents. Short-circuit between copper / aluminum concentration: battery processing or metal foreign body puncture diaphragm or electrode, battery pack in the battery package, causes positive, negative set fluid contact.

The short circuit caused by the diaphragm failure, the diaphragm, diaphragm, diaphragm corrosion, etc. can result in failure of the diaphragm, the failure diaphragm loss of electron insulation or gap is positive, negative electrode micro contact, then the local fever is severe, continuous charge and discharge will be spread to four weeks , Cause heat loss. 杂质造成短路：正极浆料中的过渡金属杂质会造成刺穿隔膜或者促使负极锂离子脱落造成内部短路。

Short-circuit caused by lithium dendrites: a lithium lactary crystal, dendritic crystal pass through diaphragm, during the long cycle. Battery design, manufacturing or battery pack assembly, design is unreasonable or local pressure will also cause internal short circuits. 在电池过冲和过流的感应过程中，还会出现短路的情况。

电池化成过程中电解液的气体摄入变化属于正常气体，但过渡消耗电解液放出气体或者正极材料放出氧气属于异常。 Often out in this soft bag battery, it will cause excessive pressure in the battery, and stroke the encapsulation aluminum membrane, internal battery contact problem, etc. 热失控热失控是指锂离子电池温度局部或整体升温，热量不能及时散发，在内部大量聚集并诱发进一步的副作用。

诱发锂离子电池热损失的因素有非正常的使用情况，即滥用、短路、高倍、高温、挤压、针刺等。 分析锂在电池负极表面的脱落，是锂离子电池常见的老化失效现象。 析锂会使电池内部活性锂离子降低，出现容量失效，枝晶穿刺会造成局部电流和热量，最终引发电池安全问题。