The Galaxy Note7 fiasco has hurt Samsung’s image. The Korean Phone maker made several recalls and changed battery manufacturers to fix the issue, but failed to do so.
Samsung promised to reveal the exact cause resulting in Galaxy Note7 explosion. Company conducted its own investigation and today revealed the cause of explosion at a press conference, held in Seoul, Korea.
DJ Koh, President of Mobile Communications Business, Samsung Electronics, shared detailed results of the investigation and expressed his sincere apology and gratitude to Galaxy Note7 customers, mobile operators, retail and distribution partners and business partners for their patience and continued support.
Battery A assessment
I. There may be multiple contributing factors relating to battery assembly/manufacturing and design that when combined led to the failure of the Note 7 in the field
A. Battery assembly/manufacturing:
• Deformation at the upper corners
B. Battery design:
• Thinner separator could lead to poorer protection and reduced tolerance to manufacturing defects
• Higher energy density in general can exacerbate the severity of a battery failure
II. One major failure mechanism is likely:
A combination of deformation at the upper corners + thin separator + repeating mechanical stresses due to cycling, causing higher possibility of separator damage leading to an ISC between aluminum and copper foil at the corner
III. Additional investigation is needed to understand the root-cause of the deformations at the upper corners
Battery B assessment
I. No evidence of device-level compatibility issues that may have contributed to the failure of the Note 7 in the field
II. There may be multiple contributing factors relating to production quality and battery design that when combined led to the failure of the Note 7 in the field
A. Production quality:
• Missing insulation tape on tab could result in higher possibility of ISC
• Bigger protrusion of welding points in tab could lead to higher possibility of separator puncture
• Misalignment of insulation tape and/or tab could bring more risk of ISC
B. Battery design:
• Thinner separator could lead to poorer protection and reduced tolerance to manufacturing defects
• Higher energy density in general can exacerbate the severity of a battery failure
III. One major failure mechanism for field incidents is likely:
The combination of (1) missing insulation tape + (2) sharp edged protrusions on tab + (3) thin separator, all leading to a high possibility of an ISC between cathode tab and anode, subsequently resulting in heating and fire
IV. Further analysis is needed to understand the root-cause of the damage to the edge/corner of the battery which results in ISC at that location
To ensure that this does not happen in future phones, Samsung has implemented a broad range of internal quality and safety processes to further enhance product safety including additional protocols. They include multi-layer safety measures and 8-point battery safety check.
Samsung has also formed Battery Advisory Group of external advisers, academics and research experts to ensure that such a history does not repeat itself.
