Synthesis of Lithium Aluminum Layered Double Hydroxide/Kaolinite Composite Adsorbents and Application for Lithium Extraction from Brines

Efficient lithium extraction from salt lakes is critical for lithium development. Lithium/aluminum layered double hydroxides (Li/Al-LDHs) exhibit high selectivity and are considered effective adsorbents for lithium recovery from salt lake brines. However, designing excellent Li/Al-LDH adsorbents with both high adsorption selectivity and cycle stability has remained highly challenging. Here, we demonstrate an adsorption resin composed of porous natural kaolinite and Li/Al-LDHs that enables efficient and stable Li + adsorption. The Li/Al-LDHs and kaolinite are mixed and plasticized into spherical porous granules. This adsorbent offers high Li + adsorption capacity for efficient lithium extraction and excellent mechanical strength for long-term use. The adsorbent was then evaluated for lithium recovery from authentic salt lake brines. Consequently, the Li/Al-LDHs-Kln adsorbent achieved a Li + adsorption capacity of 7.5 mg·g –1 at 200 mg·L –1 brines from the Qinghai Yiliping Salt Lake, which ranks among the highest values of Mg 2+ /Li + ratio at ambient temperature reported to date. After 100 adsorption–desorption cycles, the adsorbent retained a capacity above 7.0 mg·g –1 . This demonstrates strong stability in both adsorption performance and crystal structure, underscoring its potential for industrial lithium extraction. Thus, the effective application of Li/Al-LDHs adsorbent has the potential to fundamentally transform the lithium supply chain especially for lithium-ion batteries.