High-temperature (800 °C) performance of spodumene slag-based ternary sulphate composite phase change materials with improved mechanical property

The large deployment of electric vehicles leads to decarbonised road transport. However, the mining and smelting of lithium resources will continue to increase, which generates lithium slag and urgently needs to be recycled. The integration of spodumene slag with ternary sulphate presents a green and promising approach to achieve resource recycling and high-performance composite phase change material (CPCM). Herein, toughened and strengthened CPCMs are prepared by the hybrid sintering method with mechanical properties better than reinterned glass, even after high-temperature thermal cycling. After the cold compression and hot sintering process, the production of colloidal sodium silicate bonds the ternary sulphate with the spodumene slag skeleton, which greatly enhances the strength of the CPCM for efficient and durable thermal energy storage (TES). The Hydroxyl polar group of sodium silicate interacts with the skeleton and leads to a record-breaking compressive strength of 155.23 MPa, and the CPCM can support its stacking of 23.6 m and 15 kg loading test at 700 °C. A negligible mass loss of 0.26 wt% was observed after 50 thermal cycles at 800 °C. Moreover, the CPCMs exhibit a high TES density of up to 873.0 J/g in the temperature range of 100–800 °C. High charging and round-trip efficiency in the heat recovery process from spodumene roasting is also achieved, as it is 5 % and 19 % higher than the common magnesium bricks, respectively. The CPCM achieves high thermal efficiency TES, and it is the effective resource recycling of lithium slag with simple material preparation, which, from two angles at once, attacks the carbon emission from the life cycle of the lithium-ion battery.