Evaluasi Model Termodinamika dan Kinetika Presipitasi Litium Karbonat pada Proses Daur Ulang Baterai NMC

Doni Riski Aprilianto, Prof. Indra Perdana., S.T., M.T., Ph.D.; Prof. Ir. Rochmadi., S.U., Ph.D., IPU.; Prof. Himawan Tri Bayu Murti Petrus, S.T., M.E., D.Eng.

2025 | Disertasi | S3 Teknik Kimia

Peraturan Presiden Nomor 55 Tahun 2019 mendorong penggunaan kendaraan bermotor listrik berbasis baterai (KBLBB) di Indonesia. Komponen terpenting dari KBLBB adalah baterai litium yang memiliki umur pakai hanya 8 hingga 10 tahun dan kemudian menjadi limbah yang wajib didaur ulang. Proses daur ulang (recycling) menjadi krusial karena mendukung keberlanjutan material, perlindungan lingkungan, dan penerapan ekonomi sirkular. Namun, pada proses daur ulang baterai litium terdapat tantangan utama pada tahap akhir yaitu presipitasi litium dalam bentuk litium karbonat (Li?CO?) karena rendahnya konsentrasi litium dan tingginya kandungan pengotor seperti ion Na? dan SO?²?, yang berdampak pada penurunan kemurnian dan tingkat recovery produk. Selain itu, spesifikasi distribusi ukuran produk Li?CO? yang sangat ketat turut menjadi tantangan tersendiri. Oleh karena itu, penelitian ini bertujuan mengoptimalkan kondisi presipitasi Li?CO? dari daur ulang baterai litium dengan target recovery ? 70%, distribusi ukuran d₁₀ ? 1 ?m, 3 ?m ? d₅₀ ? 8 ?m, d₉₀ ? 15 ?m, dan kemurnian ? 99,5%, seperti spesifikasi pasar. Dua pendekatan digunakan, yaitu presipitasi konvensional dan berbantu ultrasound untuk mengevaluasi pengaruh konsentrasi CO?²?, SO?²?, dan suhu terhadap kemurnian dan recovery, serta pengaruh sistem pengadukan (konvensional dan ultrasound) terhadap distribusi ukuran produk. Analisis pemodelan termodinamika dan kinetika turut dilakukan guna memahami fenomena yang terjadi secara fundamental.

Hasil penelitian menunjukkan bahwa ion CO?²? meningkatkan recovery produk Li?CO?, sedangkan ion SO?²? secara konsisten menurunkan kemurnian dan recovery. Pada rasio CO?²?/Li? ? 2,0, kemurnian yang dihasilkan tetap memenuhi standar. Namun, pada rasio 2,5 terbentuk pengotor Na?CO? yang menurunkan kemurnian menjadi 92,17%, meskipun recovery naik menjadi 81,64%. Konsentrasi ion SO?²? yang tinggi juga menurunkan kualitas produk, tetapi pada rasio SO?²?/Li? = 0,5 diperoleh kemurnian 99,89?n recovery 80,54%. Pada rasio SO?²?/Li? > 0,5, diperlukan pretreatment untuk menurunkan konsentrasi ion SO?²? agar kemurnian Li?CO? tetap di atas 99,5%. Selain itu, peningkatan suhu juga meningkatkan recovery Li?CO? akibat penurunan kelarutannya pada suhu tinggi. Namun, pada konsentrasi ion SO?²? tinggi, suhu tinggi dapat memicu terbentuknya pengotor Na?SO?. Suhu presipitasi yang tinggi juga berdampak negatif terhadap ukuran partikel Li?CO? yang cenderung besar dan teraglomerasi sehingga tidak memenuhi standar. Pada sistem pengadukan konvensional 250 rpm, ukuran d₁₀, d₅₀, dan d₉₀ masing-masing sebesar 59,33 ?m; 79,55 ?m; dan 108,52 ?m. Meskipun peningkatan kecepatan pengadukan hingga 650 rpm dapat memperkecil ukuran, namun hasil akhir distribusi ukuran partikel tetap diluar standar. Sebaliknya, presipitasi berbantu ultrasound pada daya 260–320 W menghasilkan partikel sesuai spesifikasi (d₁₀ ~3 ?m, d₅₀ 5–6 ?m, d₉₀ <15>

Penelitian ini juga mengevaluasi pemodelan termodinamika dan kinetika untuk memahami fundamental proses presipitasi, terutama dalam kontrol kemurnian, recovery, dan distribusi ukuran produk. Model termodinamika berbasis persamaan Gibbs excess dengan modifikasi Full Debye-Hückel dan Ionic Association Term (FDH-IAT) secara akurat memprediksi kelarutan Li?CO? dalam sistem non-ideal. Model kinetika berbasis Population Balance Model (PBM) berhasil menggambarkan dinamika nukleasi dan pertumbuhan partikel pada sistem presipitasi berbantu ultrasound. Model termodinamika dan kinetika yang dikembangkan tersebut menghasilkan parameter yang sensitif dan general, sehingga mendukung simulasi dan scaling-up proses industri daur ulang baterai NMC terutama dalam meningkatkan kontrol dan prediksi kemurnian, recovery, dan distribusi ukuran produk Li?CO?.

Presidential Decree No. 55/2019 promotes the adoption of battery electric vehicles (BEVs) in Indonesia. The most critical component of BEVs is the lithium-ion battery, which has a limited lifespan of 8 to 10 years and eventually becomes waste that must be recycled. Recycling spent batteries is essential to support material sustainability, environmental protection, and the implementation of a circular economy. However, recycling of lithium-ion batteries faces a major challenge in the final stage, which involves the precipitation of lithium as lithium carbonate (Li?CO?). This challenge arises from low lithium concentration and presence of impurities such as Na? and SO?²? ions, which reduce both the purity and recovery rate of Li?CO?. In addition, the strict specifications for Li?CO? particle size distribution pose an additional challenge. This study aims to optimize the precipitation conditions for Li?CO? recovery from recycled lithium batteries, targeting a recovery rate of ? 70%, a particle size distribution of d₁₀ ? 1 ?m, 3 ?m ? d₅₀ ? 8 ?m, d₉₀ ? 15 ?m, and a purity of ? 99.5%, in accordance with battery-grade standards. Two approaches, conventional precipitation and ultrasound-assisted precipitation, were applied to the study of Li?CO? precipitation. The effects of CO?²? and SO?²? concentrations and temperature on purity and recovery rate were evaluated, along with the effects of different agitation methods (conventional and ultrasound) on particle size distribution. Thermodynamic and kinetic modeling was also conducted to understand the underlying mechanisms of the precipitation process.

The results show that CO?²? ions increase the recovery of Li?CO?, while SO?²? ions consistently reduce both purity and recovery. At a CO?²?/Li? molar ratio of ? 2.0, the resulting purity meets the required standard. However, at a ratio of 2.5, Na?CO? impurities form, reducing the purity to 92.17?spite an increased recovery of 81.64%. A high concentration of SO?²? also lowers product quality, but at a SO?²?/Li? ratio of 0.5, a purity of 99.89% and a recovery of 80.54% were achieved. When the SO?²?/Li? ratio exceeds 0.5, pretreatment is required to reduce the SO?²? concentration in order to maintain Li?CO? purity above 99.5%. Temperature also affects recovery, with higher temperatures increasing Li?CO? recovery due to reduced solubility. However, in the presence of high SO?²? concentrations, elevated temperatures can lead to the formation of Na?SO? impurities. In addition, high precipitation temperatures negatively affect particle size, resulting in large and agglomerated Li?CO? particles that do not meet specifications. Under conventional agitation at 250 rpm, the resulting particle sizes were d₁₀ 59.33 ?m, d₅₀ 79.55 ?m, and d₉₀ 108.52 ?m. Although increasing the agitation speed reduced particle size, the final distribution still did not meet the standard. In contrast, ultrasound-assisted precipitation at 260–320 W produced particles that met specifications (d₁₀ ~3 ?m, d₅₀ 5-6 ?m, and d₉₀ <15>

The study also included thermodynamic and kinetic modeling to better understand the Li?CO? precipitation process, particularly to control purity, recovery, and particle size distribution. The thermodynamic model, based on the excess Gibbs free energy equation with Full Debye-Hückel and Ionic Association Term (FDH-IAT) modifications, accurately predicted Li?CO? solubility in non-ideal systems. The kinetic model, using the Population Balance Model (PBM), successfully described nucleation and particle growth dynamics in the ultrasound-assisted system. These models provided sensitive and general parameters that support simulation and industrial scale-up of NMC battery recycling processes, especially for enhancing control and prediction of Li?CO? purity, recovery, and size distribution.

Kata Kunci : daur ulang; presipitasi Li?CO?; recovery; kemurnian; distribusi ukuran