As　draw　solute　is　the　core　element　of　forward　osmosis　(FO)　technology,　here　Li-Bet-Tf2N　synthesized　from　a　customized　ionic　liquid　betainium　bis(trifluoromethylsulfonyl)imide　([Hbet][Tf2N])　and　Li2CO3　recovered　from　lithium-ion　battery　(LIB)　wastes　is　proposed　as　a　novel　draw　solute　to　treat　Li+-containing　wastewater　from　LIB　manufacturing　through　FO　filtration.　Having　high　dissociation　ability　and　an　extended　structure,　Li-Bet-Tf2N　generates　a　sufficiently　high　osmotic　pressure　to　drive　the　FO　filtration　efficiently　along　with　insignificant　reverse　solute　diffusion.　Li-Bet-Tf2N　produces　a　water　flux　of　21.3　L·(m2·h)−1　at　1.0　mol·L−1　against　deionized　water,　surpassing　conventional　NaCl　and　MgCl2　draw　solutes　with　a　higher　water　recovery　efficiency　and　a　smaller　solute　loss.　Li-Bet-Tf2N　induces　a　more　stable　and　higher　water　permeation　flux　with　a　10.0%　water　flux　decline　than　NaCl　and　MgCl2　for　which　the　water　fluxes　decline　16.7%　and　16.4%,　respectively,　during　the　treatment　of　2000　mg·L−1　Li+-containing　wastewater　for　12　h.　More　remarkably,　unlike　other　draw　solutes　which　require　intensive　energy　input　and　complicated　processes　in　recycling,　Li-Bet-Tf2N　is　easily　separated　from　water　via　solvent　extraction.　Reproducible　results　are　achieved　with　the　recycled　Li-Bet-Tf2N.　Li-Bet-Tf2N　thus　demonstrates　a　novel　class　of　draw　solute　with　great　potentials　to　treat　wastewater　economically.　[Figure　not　available:　see　fulltext.]　©　2022,　Higher　Education　Press.