CNC SPM DEVELOPMENT FOR AUTOMATED SPOT WELDING BETWEEN LI-ION BATTERY AND SHEET METAL CONNECTOR

The development of the CNC Special Purpose Machine (SPM) for lithium-ion battery spot welding represents a significant leap in manufacturing efficiency and product reliability for the electric vehicle (EV) sector. This project successfully addressed the critical bottleneck in battery pack assembly by transitioning from manual, labour-intensive soldering and welding processes to an automated 3-axis CNC system. The study conclusively demonstrated that the implementation of automation not only scales production but also fundamentally improves the electrical and mechanical integrity of the battery connections. A primary achievement of this work was the optimization of welding parameters, including electrode tip geometry, welding force, and current timing, which were validated through both finite element analysis (FEA) in Ansys and physical experimentation. The analysis revealed that manual wire soldering often led to heat generation issues and localized resistance, which negatively impacted battery performance. By adopting CNC-controlled spot welding with copper or nickel strips, the company achieved higher conductivity, leading to faster charging rates and improved discharge performance. Future iterations could explore the integration of Laser Beam Welding (LBW) or Ultrasonic Metal Welding (UMW). While resistance spot welding is cost-effective, LBW offers a more concentrated heat source with smaller spot sizes, which can further reduce the heat-affected zone and prevent potential damage to sensitive battery chemistry. Similarly, UMW is a solid-state process that could eliminate melting altogether, providing excellent bonds for thin foils and multi-layered connectors

  [1].  Vidyasagar, B.,  Varma,  N.  R.,  Dhasharatha,  G.,  & Reddy,  K.  C.  (2024).  Design  of  Electrical  Vehicle Lithium  Battery  Charger  Using  MATLAB  Simulink. In  Disruptive  technologies  in  Computing  and Communication Systems (pp. 379-385). CRC Press. [2].  Varma,  N.  R.,  Reddy,  K.  C.,  Dhasharatha,  G., Manohar,  V.,  Kumar,  K.  K.,  &  Kumar,  V.  P. (2024). Hybrid  Electrical  Vehicle  Design  by  Using  Solar and Battery  Sources.  In E3S  Web  of  Conferences (Vol. 472, p. 01006). EDP Sciences. [3].  Li, Z., Wang, J., & Chen, H. (2017). Impact of nickel strip  resistivity  on  internal  resistance  and  energy losses in lithium-ion battery packs. Journal of Energy Storage, 14, 125-135. [4].  Manohar,  V.,  Dhasharatha,  G.,  Santhosh,  K.,  Nithin, M.,  Teja,  M.  R.,  &  Akshay,  M.  (2024).  EcoCharge: Wireless  Power  Hub  for  Electric  Vehicles. CVR Journal of Science and Technology, 26(1), 76-80. [5].  Zhang,  Q.,  Lee,  A.,  &  Kim,  Y.  (2019).  Effects  of nickel  strip  thickness  on  resistance  and  battery  pack performance. Journal of Power Sources, 28, 223-231. [6].  Park,  S.,  Choi,  D.,  &  Moon,  S.  (2018).  Influence  of parallel  nickel  strip  configurations  on  voltage  drop and  power  delivery  in  battery  packs.  IEEE Transactions on Energy Conversion, 33(5), 432-440. [7].  Wu,  X.,  Lin,  P.,  &  Zheng,  W.  (2020).  Enhancing battery  performance  with  coated  nickel  strips: Resistivity  and  corrosion  resistance  analysis. Electrochimica Acta, 345, 112–121. [8].  Liu, J., Yuan, C., & Zhao, K. (2021). Comprehensive analysis  of  internal  resistance  and  voltage  drop  in lithium-ion  battery  packs.  Journal  of  Energy  Science and Engineering, 36, 288-300. [9].  Chen,  L.,  Tan,  H.,  &  Yu,  S.  (2022).  High-load performance  analysis  of  battery  packs:  Reducing energy  losses  through  advanced  interconnect materials.  *Journal  of  Applied  Electrochemistry*, 57(2), 211-224. [10].  Yang,  W.,  Zhang,  L.,  &  Huang,  F.  (2023).  Impact  of bending  points  on  nickel  strip  resistance  in  battery packs:  A  localized  analysis.  Journal  of Electrochemical Engineering, 59, 178-187.