A toddler is "lucky to be alive" after acid from a battery she swallowed "burned through her lung".
Sophie Skill, two, spent six days on life support following an emergency operation after swallowing a lithium battery the size of a 10p.
Having now recovered after spending nearly two months in hospital, her mum Clare Skill wants to raise awareness of these dangers.
"I really want to make other parents aware of the implications of what can happen if your child gets hold of one of these batteries," the mum urged.
"I had no idea of the dangers, but now if I ever see one again it will be too soon."
Sophie began crying and holding the back of her neck after swallowing the battery
Skill said her daughter was playing in the front room in July 2015 when she noticed she had become agitated and teary.
She soon became very distressed, crying excessively and holding the back of her neck.
"She was so distressed, and I just knew she had swallowed something," said Skill. "My heart was beating so fast."
She immediately took her daughter to hospital, where an X-ray showed she had swallowed the small battery.
Within two hours of arriving at Sheffield Children's Hospital, Sophie was rushed to surgery to have it removed.
Skill said: "As soon as they knew what it was, it all became much more urgent."
The battery was removed from her food pipe, but as the inflamed area around her throat had swollen over, they were unable to immediately detect a hole caused by the corrosive acid.
Doctors discovered the battery had "burned through" Sophie's lung
After 24 hours, nurses noticed Sophie wasn't recovering properly from the operation. More tests and a second X-ray uncovered the hole in her throat that was showing signs of infection.
They also discovered the acid had "burned through her lung".
The two-year-old was immediately rushed to intensive care where they put in a chest drain and put her on a ventilator to help her breathe.
Her mum added: "I was just so scared, thinking the worst.
"After a week, she had a CT scan and it showed the hole wasn't healing and was in fact getting bigger because the acid was continuing to corrode her oesophagus."
Sophie was sent to theatre again, where a surgeon fitted a special 'T' tube from the hole to her stomach to drain fluid out of her body. Tissue was taken from Sophie's side and put around the hole to allow it to heal.
The toddler was then put on life support for six days.
Skill said: "She was put under general anaesthetic at least eight times during her eight weeks in hospital.
"She was ventilated six times and spent three weeks in intensive care. It was petrifying seeing her like that.
"She was in pain, and I just wanted so much for her to be better. I realise now that if it wasn't for the surgeon putting that 'T' tube in, she wouldn't be here today."
Sophie, who swallowed the battery in July, was discharged in September after her throat healed.
Sophie is "running around like nothing happened
Sophie now has to take an alkaline tablet each day, but has no lasting damage.
"She is fantastic now, running around like nothing ever happened," her mum said. "She is a really happy little girl, and is looking forward to celebrating her third birthday next month."
Her family want to warn parents of the dangers of button batteries, and launch a major fundraising campaign to say thank you to the Sheffield Children's Hospital specialists who kept her alive.
Dad Wayne Skill said: "By fundraising we want to help in any way we can, to repay them for what they have done for Sophie, because if it wasn't for them she wouldn't be here."
Sophie's Grandfather John Johnson is hoping to lead 100 kind-hearted walkers on a Five Peak Challenge in June to raise money for The Children's Hospital Charity.
He said: "Sophie had so many mountains to climb in her treatment, so we wanted to do something that would represent that and present a challenge for us."
The money they raise will help the charity's Make it Better new wing appeal.