Battery Cell Terminal Assembly With Stepped Busbar Welding Interface

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Solution Overview

Problem

The welding yield of busbars in battery cells is poor due to unstable connections between the sealing cover and the busbar, which affects the overall operation performance of the battery cell.

Innovation Solution

A terminal assembly design with a joint protrusion on the sealing cover that protrudes beyond the welding seam to accommodate the connection with the busbar, ensuring a stable and secure electrical connection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If welding is performed between the sealing cover and the busbar, then electrical connection is achieved, but the welding seam interferes with the connection between the joint protrusion and the busbar, resulting in poor welding yield

Engineering Contradiction:
Improvewelding yieldVSAvoidconnection structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The sealing cover is divided into two functional parts: the body (for welding to the terminal) and the joint protrusion (for connecting to the busbar). This segmentation allows the welding seam to be contained on the body surface while the joint protrusion provides a separate, clean connection interface, eliminating interference between the welding seam and the busbar connection.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The joint protrusion extends in the thickness direction of the sealing cover, creating a three-dimensional structure that elevates the connection interface above the welding seam plane. This dimensional separation ensures that the welding seam does not interfere with the busbar connection, as they operate at different spatial levels.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If the joint protrusion is designed to connect to the busbar, then electrical connection stability is improved, but the manufacturing precision requirements increase due to the need for accurate welding seam accommodation

Engineering Contradiction:
Improveconnection stabilityVSAvoidwelding seam height control
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The joint protrusion is pre-formed with a specific height that is greater than or equal to the maximum height of the welding seam. This preliminary design ensures that even with variations in welding seam height, the joint protrusion will always accommodate the welding seam and provide a stable connection surface, reducing the impact of manufacturing precision variations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The excess height of the joint protrusion (beyond the welding seam height) acts as a cushion or buffer zone. This design margin compensates for potential welding seam height variations and ensures consistent connection quality, effectively cushioning against manufacturing precision issues before they can affect the final product.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The design enhances the welding yield of the busbar by preventing the welding seam from interfering with the connection, thereby improving the stability and quality of the connection between the sealing cover and the busbar, ensuring reliable operation of the battery cell.

Implementation Method 1

the body being matched with the terminal through welding to block the electrolyte solution filling channel, a welding seam being formed at a joint between the body and the terminal

Methodology Applied
Scientific EffectWelding: Welding

Data Source

PatentEP4625632A1Terminal assembly of battery cell, battery cell, battery assembly, and electric device
Publication Date: 2025.10.01 BYD CO LTD
  • EP4625632A1 patent drawingFigure 1~2
  • EP4625632A1 patent drawingFigure 3~4
  • EP4625632A1 patent drawingFigure 5~7

AI summary

The present disclosure discloses a terminal assembly of a battery cell, a battery cell, a battery assembly, and an electrical device. The terminal assembly of the battery cell includes a terminal and a sealing cover (230). An electrolyte solution filling channel (211) is provided in the terminal. The sealing cover includes a body (231) and a joint protrusion (232). The body is matched with the terminal through welding to block the electrolyte solution filling channel, and a welding seam (290) is formed at a joint between the body and the terminal. The joint protrusion is arranged on a first end surface that is of the body and that is away from the electrolyte solution filling channel along a thickness direction. The joint protrusion is adapted to connect to a busbar (2000). The joint protrusion protrudes out of the body to form a step for accommodating the welding seam, so that a protrusion height of the joint protrusion is greater than or equal to a maximum height of a part that is of the welding seam and that protrudes out of the first end surface. In the terminal assembly of the battery cell according to embodiments of the present disclosure, quality and stability of a connection between the sealing cover and the busbar can be ensured.