材料对锂离子电池热稳定性的影响

采用差示扫描量热法研究锂离子电池材料包括导电剂、粘结剂、电解液、Li0.5CoO2与LiC6对锂离子电池热稳定性的影响,并对由这些材料制备的063048型方形锂离子电池进行安全性测试.研究结果表明:锂离子电池的热稳定性受正极、负极及电解液3种因素的影响,电池热反应释放的热量由大到小顺序为:负极、正极、电解液.负极反应热主要来源于LiC6与粘结剂及电解液之间的反应,且与粘结剂的性质、用量及电解液用量有关;正极反应热主要来源于Li0.5CoO2的分解反应及其分解产生的氧气与有机溶剂之间的燃烧反应.聚偏二氟乙烯粘结剂比丙烯酸系水基粘结剂的热稳定性高,导电碳黑导电剂的热稳定性比乙炔碳黑导电剂的热稳定性高.过充实验结果表明,聚偏二氟乙烯粘结剂及导电碳黑能显著提高LiCoO2/石墨型锂离子电池的热稳定性.

Influence of materials on thermal stability of lithium-ion batteries

Differential scanning calorimetry (DSC) was used to study the influence of materials on the thermal stability of lithium-ion batteries. The materials included conductive carbon black, (acetylene) carbon back, polyvinylidene fluoride(PVDF) adhesive, acrylic adhesive, Li_(0.5)CoO_2 and LiC_6. The safety test was carried out on 063048 prismatic lithium-ion batteries. The results show that PVDF adhesive and conductive carbon black exhibit better thermal stability compared with acrylic adhesive and acetylene carbon black. The total reaction heat of each influencing factor responsible for the thermal stability of lithium-ion batteries from large to small is as follows: anode, cathode, electrolyte. The anode reactions mainly take place among LiC_6, adhesives and electrolyte. The reaction heat is strongly influenced by the nature and amount of adhesive and electrolyte. The released heat in cathode mainly resulted from organic solvent combustion reaction due to the evolved oxygen from Li_(0.5)CoO_2 decomposition at elevated temperature. The overcharging experiments show that the safety of LiCoO_2/graphite lithium-ion battery can be improved by choosing PVDF as adhesive and conductive carbon black as conductive additive.