The Galaxy Note 7 has had arguably the worst launch of any smartphone ever, but Samsung’s bombshell isn’t the first -or the last- dangerous device.

Seoul-based news agency Yonhap News first reported on Thursday, September 1st, 2016 that the South Korean electronics magnate had halted shipments amidst rumors of battery explosions. The first reports of exploding batteries came out on August 24th, only a week after the phone’s international release. Just over a month later, Samsung officially recalled 2.5 million phones, only 1 million of which were actually sold, costing the organization an estimated $5 billion US in losses.  Unfortunately, the Note 7 isn’t the only phone that has the capability to combust, and it isn’t the first phone to be recalled because of safety concerns.

The Galaxy Note 7 uses a lithium-ion battery, the most common battery in portable technology. They are found (with some variations in size and structure) in nearly every mobile phone, laptop, and piece of wearable technology. The Battery University explains that these batteries consist of three main components: a positively charged cathode, a negatively charged anode, and an electrolyte – commonly called battery acid between them, which facilitates the interaction between the two charged pieces.

When a device is plugged in to charge, electricity flows into the anode, where it is stored in the anode. When an anode is fully charged, attempting to add more electrons overcharges the battery, leading to damage which directly impacts the device’s performance. This is the reason that an old phone, which has been used and recharged repeatedly, has a worse battery life than a newer model of the same phone. When a given device is being used, the charged particles move to the cathode, where their charge is released as electricity into the device, powering it until the electrons run out, at which point it needs to be recharged.

Rechargeable batteries, like the ones used in mobile phones, measure their power in milli-amp hours, or mAh. Fortune reports that the The Note 7 carries an impressive 3,500 mAh, nearly double the iPhone 7’s 1,960 mAh. Unfortunately for Samsung, their pursuit for a vastly superior battery led to the Note 7’s fire issues.

Bloomberg Technology explains that in an attempt to make the battery as powerful, yet simultaneously thin and compact, a manufacturing and design issue created contact pressure between the anode and cathode sections of the battery. This issue could have been created by Samsung’s desire to release the phone in time to compete with the iPhone 7. When the battery was used to a certain extent, such as when it was being charged overnight or simply using power for background applications, the electrolyte barrier broke down. This breakdown results in the rapid exchange of energy between the two sides, heating up the incredibly flammable contents at the the site of the break. A Samsung official told Yonhap news that only 0.01% of devices, or about 1,000 phones, were defective.

“It is a very rare manufacturing process error.” the official said to CNET.

MIT materials chemistry professor Don Sadoway has two theories about why these batteries were exploding. The first involves the phone’s software, which tells the battery when it is “full” so that it can stop charging itself. In an interview with CNET, Sadoway details how he believes that this data was somehow incorrect, leading to rapid overcharging, which in turn short circuited the batteries. This theory explains why several phones exploded why being charged, often overnight.

Sadoway’s other theory spells out how the batteries had tiny fragments of the cathode imbedded in the electrolyte barrier. This created a path of least resistance through the battery, allowing a large scale reaction over a short period of time. As Sadoway said in an interview with Time Magazine, “[This] has now become a bomb. You’ve got fuel and oxygen in the same place at the same time.” Other reports of phones experiencing similar problems while not charging, such as the case of a Note 7 burning in a man’s pocket while he was on a plane, are a result of the damage the battery sustained through repeated overcharging.

When Samsung first learned of these significant problems, they issued a press release that urged people to get their phones replaced with a new, “safe” version. Unfortunately, these seemingly harmless phones had similar defects, giving credence to the theory that the batteries were not entirely at fault.

Samsung is not the only company to have a history of battery explosions and fires. In fact, an iPhone 7 experienced a very similar problem while in transit to a customer’s house. An Australian cyclist also suffered third-degree burns on his right leg after he fell on his iPhone 7 in a minor collision.

Samsung aims to steadily recover from their losses with the Galaxy Note 8, scheduled to be released in 2017. iTech reports that the company is heavily focused on rebuilding their brand through devotion to safety. It is still unclear if the phone will deliver promises of a non-lithium ion battery, possibly leading to a safer overall experience. Samsung also hopes to increase screen size and resolution, along with significant performance improvements.

Although the Galaxy Note 7 was a step back for Samsung, it has not been the first case of technology risking users’ safety. As technology evolves, safety has often taken a backseat to innovation. Electronics, like any new technology, have always posed a risk to society, and it is important to remember that no forward movement guarantees absolute security.