In recent years, consumer demand for smaller and more powerful electronic devices has led to a large increase in the usage of batteries worldwide. Advances in sophisticated electronic items such as laptop computers and mobile phones require these batteries to be more sustainable, smaller and lightweight. The gravimetric energy density is 110-160 and 30-50 Wh/kg for lithium ion and lead acid batteries respectively. Owing to its merit, such as a high energy density, a high working voltage, a long cyclic life and negligible memory loss effects, the lithium ion batteries are state of the art and also remain the battery system with the highest potential for future development. With increasing use of such batteries in the developed countries for transportable applications, and large untapped markets in the developing countries, the need for lithium ion batteries will increase by orders of magnitude. This has led to growing concerns worldwide about the disposal of batteries and the potentially harmful impact they may have on the environment. However, spent batteries also represent a concentrated source of high value metal. Therefore, it is important that a system for recycling and regenerating waste lithium ion batteries is developed. Owing to the explosive nature of metallic lithium, spent lithium primary batteries cannot be disposed safely unless metallic lithium is properly removed from them. In contrast, lithium ion secondary batteries use a lithium conducting cathode made from a non-explosive 'mixed oxide', allowing a wider selection of recycling techniques. These mixed oxides often contain valuable cobalt, which has a high economic value for recycling owing to the fact that natural sources for cobalt are limited, and its uses are diverse and steadily increasing. The objective of the present work is to outline the dissolution characteristics of the cathodic active materials from spent lithium ion secondary batteries in sulfuric acid media, and to recover cobalt and lithium separately as their sulfates by sulfate precipitation method using ethanol. Despite long leaching time and high leaching temperature, it was observed that cobalt, which is present in the LiCoO2 compound, dissolved into concentric sulfuric acid media with poor dissolution efficiency. The reason for this is that the oxidation level of the cobalt in the LiCoO2 compound is +3, so it should be reduced to +2. Hydrogen peroxide, known as both good oxidizer and reducer, is an ideal option for this reduction. Using 5% H2O2, at 80oC, at 300 rpm, the LiCoO2 compound was found to dissolve into 4M H2SO4 in an hour with 100% dissolution efficiency. Cobalt was recovered in two steps. During the first step, 92% of the cobalt is recovered as CoSO4 by the use of ethanol at a volume ratio of 3:1. Ethanol removes water ligands from the Co2+ cation, and caused the precipitation of cobalt as cobalt sulfate monohydrate. In the second step, the remaining cobalt was precipitated as cobalt hydroxide (Co(OH)2) by increasing the pH value up to 10 with the addition of lithium hydroxide (LiOH). Lithium, which remained in the solution, was then recovered as lithium sulfate (Li2SO4) with up to 98% recovery efficiency by the addition of ethanol at a 3:1 volume ratio. It was shown that metals could be precipitated separately by this technique depending on their concentrations present in the solution. Using this selective precipitating characteristic of ethanol, it was managed to precipitate the cobalt with high efficiency without promoting the precipitation of the lithium. The advantage of this technique over more classical techniques for salt crystallization is that no temperature shift is needed, and the product will be intrinsically low in water, unlike the more classical separation by crystallization, which requires heat (or at least temperature control) and tends to yield a metal sulfate with a high amount of crystalline water. The leach acids may be reused in feedback loops. Also, it is possible to recover ethanol by distillation. By doing so, the recovered ethanol could be reused for precipitating sulfates from sulfuric acid solutions. The proposed process can be used to treat spent Li-ion secondary batteries, and to recover valuable cobalt and lithium without posing environmental problem. Keywords: Li-ion batteries, recycling, precipitation method with ethanol, Li and Co recovery. Bu çalışmada, lityum iyon ikincil pillerinde katodik aktif malzeme görevi gören lityum kobalt oksit (LiCoO2) bileşiğinin sülfürik asit ile liç davranışları optimize edilerek, çözeltiye geçen lityum ve kobaltın etanol sülfat çöktürme tekniği ile sülfatları şeklinde çöktürülme şartları incelenmiştir. Yeniden kullanılabilir malzemeleri maksimum seviyede geri kazanmak ve böylece bitmiş pillerin çevreye yapacağı kirliliği minimuma indirmek amaçlanmıştır. 80oC sıcaklıkta 1 saat boyunca çözümlendirme işlemi için kullanılan %5 hidrojen peroksit içeren 4M sülfürik asit çözeltisi ile lityum ve kobaltın tamamı çözeltiye geçmiştir. Çözeltiye geçen kobalt iki aşamada geri kazanılmıştır. Birinci adımda, çözeltideki kobalt iyonları, 3:1 etanol/çözelti hacimsel oranında etanol ilavesiyle CoSO4 şeklinde %92 verim ile çöktürülmüştür. Etanol, çözeltideki sülfat ligant bağlarının kırılmasını sağlayarak kobaltın, kobalt sülfat tuzu (CoSO4) şeklinde çökmesini sağlamıştır. İkinci adımda, etanol ile çökmeyen kobalt iyonları, lityum hidroksit ile pH 10’a getirilerek kobalt hidroksit (Co(OH)2) şeklinde çöktürülmüştür. Çözeltideki lityum iyonları da sülfürik asit ile asitlendirildikten sonra 3:1 etanol/çözelti hacimsel oranında etanol ilavesiyle %98 verim ile lityum sülfat (Li2SO4) şeklinde çöktürülmüştür. Etanol sülfat çöktürme tekniği ile metallerin başlangıç konsantrasyonlarına bağlı olarak selektif olarak çöktürüldükleri gösterilmiştir. Ayrıca diğer metotların aksine etanol sülfat çöktürme metodu ile yapılan çöktürme işleminde sıcaklık değişimine ihtiyaç yoktur ve elde edilen ürün düşük miktarda kristal su içermektedir. Anahtar Kelimeler: Li-iyon pilleri, geri dönüşüm, etanol sülfat çöktürme, Li ve Co kazanımı. 
