Superalgebras have been used in various questions of algebra in a very striking way. To give some instances:
Kemer's proof of the fact that, over a field of zero characteristic, every system of identities expressible in terms of the product in associative algebra follows from finitely many of them (https://link.springer.com/article/10.1007/BF01978692).
Nilpotence results by various authors, see, for instance, Zelmanov's celebrated proof of global nilpotence of Engel Lie algebras (https://link.springer.com/article/10.1007/BF00970273), or the survey of Vaughan-Lee indicating some other directions (https://www.worldscientific.com/doi/10.1142/S0218196798000065)
Shestakov's elegant examples and counterexamples in different varieties of nonassociative algebras (https://link.springer.com/article/10.1007/BF00971214)